2005 Sidney – Agenda & Abstracts

Wednesday, 4 May 2005

Denis d’AmoursInstitute of Ocean Sciences and Director of the Canadian Hydrographic Service PacificWelcome and Introduction
Phil WeaverSouthampton Oceanography CentreEuropean perspective HERMES Project
Dick PickrillGeological Survey of CanadaHabitat Mapping and National Seafloor Mapping Strategies in Canada
Peter T. HarrisGeoscience AustraliaRecent applications of geological information in the selection of candidate marine protected areas in Australia
Janine GuinanNational University of Ireland GalwayVideo and multibeam observations of mega-benthic habitats in the Rockall Trough, Irish continental margin, using a remotely operated vehicle; implications for managing deep-sea habitat
Oddvar LongvaGeological Survey of NorwayThematic maps for coastal planning
Alan  StevensonBritish Geological SurveyThe new British Geological Survey marine and coastal mapping project: Recent progress
Curt E. WhitmireNOAA FisheriesA quantitative approach for using multibeam sonar data to map benthic habitats
Alan SinclairFisheries and Oceans CanadaGroundfish distribution and bottom type in Hecate Strait and Queen Charlotte Sound
Guy CochraneUS Geological SurveyBenthic habitat mapping prior to removal of the Elwha Dam; preparing for change
Roger CogganCentre for Environment, Fisheries and Aquaculture ScienceApplication of seabed character interpretations to broad scale habitat mapping: a case study from the eastern English Channel
David S. LimpennyCentre for Environment, Fisheries and Aquaculture ScienceThe use of habitat mapping tools in the assessment of the re-habilitation of the seabed following marine aggregate extraction
S.L. PhilpottBritish Geological SurveyEastern English Channel large-scale seabed habitat maps: Helping to support the sustainable management of offshore resources
F. O. NitscheLamont-Doherty Earth ObservatoryVariation of physical environments and habitats in the Hudson River Estuary

Thursday, 5 May 2005

Ron McDowell Transborder Habitat Mapping Project: Sponsors Perspective
J.W.C. JamesBritish Geological SurveyThe Outer Bristol Channel marine habitat study: Interim results
Alison CopelandMemorial University of NewfoundlandBenthic habitat mapping in Newman Sound – A Newfoundland Fjord
Candace Rose-TaylorMemorial University of NewfoundlandAcoustic seabed classification and mapping of capelin spawning habitats in coastal Newfoundland
H. Gary GreeneMoss Landing Marine LaboratoriesProgress in mapping marine benthic habitats in the inland seas of the San Juan Islands, USA and Southern Georgia Strait, Canada – A major international effort
Andrew LanierOregon State UniversitySurficial geological habitat map of the Oregon and Washington continental margin, 2nd Edition
Kim PicardGeological Survey of CanadaGeological mapping of the Strait of Georgia: Application to rockfish conservation and habitat
K. Lynne YamanakaFisheries and Oceans CanadaUsing substrate maps for quillback rockfish (Sebastes maliger) stock assessment and management in the southern Strait of Georgia, British Columbia
Chris RomsosOregon State UniversityCooperative research and exploration: Multibeam sonar surveys and habitat mapping of the seafloor within the Cowcod Conservation Areas (CCA), Southern California Continental Borderland
Terje ThorsnesNorwegian Geological SurveyHabitats and seascapes in Norwegian waters – A bird's perspective
Chris RoperRoper Resources LimitedHabitat mapping using an autonomous underwater vehicle: the GAVIA system
Ole ChristensenNorwegian Geological SurveyUsing angular response curves for sediment classification and to extract geoacoustic parameters
Grady TuellOptech International Inc.Improvements in habitat mapping by fusion of bathymetric LIDAR and hyperspectral data
Klaus C. LeurerNational University of Ireland GalwayCharacterisation of near-surface ocean bottom sediments from seismic profiling data – forward model and neural-network inversion scheme
Jiashun YuInstitute of Geological and Nuclear SciencesModelling multibeam back scatterings from a rough seabed

Friday, 6 May 2005

Robin J. BeamanUniversity of TasmaniaPhysical proxies to predict biological assemblages on a tropical shelf: An example from the northern Great Barrier Reef, Australia
Michael ParkeNOAA Pacific Islands Fisheries Science CenterBenthic characterization using multibeam bathymetry, towed video, and spatial statistics
John R. HarperCoastal and Ocean Resources Inc.Combining acoustic and visual surveys for nearshore habitat mapping
V. HühnerbachSouthampton Oceanography CentreMapping of potential habitats in a deep-water coral reef off Norway: A comparison of visual and computer-assisted methods to interpret sidescan sonar data
Margaret WilsonNational University of Ireland GalwayMulti-scale terrain analysis of multibeam data from the Irish continental slope
Rebecca J. AlleeNOAA Restoration CenterUsing benthic mapping data to evaluate the coastal/marine ecological classification standard
Neil GoldingJoint Nature Conservation CommitteeDeveloping a marine landscape classification for UK seas
Brian ToddGeological Survey of CanadaThe First GeoHab Publication – “Characterization and mapping of seafloor conditions for the use of habitat delineation based on the latest technologies and methodologies”: Contents and status

Posters

Cleo BrylinskyAlaska Department of Fish and GameVolcanic edifices of Southeastern Alaska as promising groundfish habitat
S.E. CookUniversity of VictoriaHabitat mapping of Hexactinosidan sponge reefs using video and multibeam bathymetry
Alison CopelandMemorial University of NewfoundlandBenthic habitat mapping in Newman Sound – A Newfoundland Fjord
G.K. DavorenUniversity of ManitobaImportance of capelin (Mallotus villosus) biology in sustaining trophic interactions in the Northwest Atlantic
C. GrandinFisheries and Oceans CanadaIncorporating interpreted geological survey data and rockfish observations into stock assessments
A.J. GrehanNational University of Ireland GalwayPreliminary results obtained using a ROV mounted RESON SEABAT 7125 multibeam during recent deep-water habitat mapping surveys
Merran HagueSimon Fraser UniversityThe use of genetic tagging to assess abundance and distribution of inshore rockfish (Sebastes spp.) within a small marine conservation area in the Strait of Georgia, British Columbia
Jodi HarneyUS Geological SurveyBenthic habitat mapping in Glacier Bay, Southeast Alaska
V.A.I. HuvenneSouthampton Oceanography CentreThe use and consistency of grey level co-occurrence matrices for the classification of sidescan sonar data from repeated surveys over deep-water coral habitats
K. IwanowskaGeological Survey of CanadaManaging systematic residual errors in multibeam backscatter data
Maria Jose Juan JordaOregon State UniversityIntegration of oceanographic information from the Heceta Bank Region off Oregon into fisheries management
Lynn LeeWorld Wildlife Fund CanadaCollaborative Science & Mapping: Piloting the waters to chart groundfish along the British Columbia coast
David S. LimpennyCentre for Environment, Fisheries and Aquaculture ScienceThe use of habitat mapping techniques in the assessment of the recoverability of the seabed following aggregate extraction - Results of a four year study
Holly L. LopezMoss Landing Marine LaboratoriesCharacterizing bedform habitat based on high-resolution multibeam bathymetry, backscatter and video imagery in the San Juan Islands, Washington, USA, and Boundary Pass Region, British Columbia
D.G. MassonSouthampton Oceanography CentreThe geology and geophysics of habitat mapping on the continental slope NW of the UK
Alan R. OrpinGeological Survey of CanadaTowards a statistically valid method of textural seafloor characterization of benthic habitats
Jane A. ReidUS Geological SurveySediment distributions along the continental shelves of the west coast, United States
Natalie A. StromOregon State UniversityStructure-forming benthic invertebrates: Habitat associations on Oregon's continental margin
Gez ThulbournJoint Nature Conservation CommitteeThe ‘MESH' Project: Mapping European Seabed Habitats
Brian J. ToddGeological Survey of CanadaNew marine map series from the eastern Canadian continental shelf
Brian J. ToddGeological Survey of CanadaApplication of multibeam bathymetry and surficial geology to the spatial management of scallops (Placopecten magellanicus) in southwest Nova Scotia
Vera Van LanckerGhent UniversityOverview of predictive modelling tools as an aid for the broad- and fine-scale mapping of European seabed habitats
Curt E. WhitmireNOAA Fisheries, Northwest Fisheries Science CenterMapping the distribution of cold-water corals and sponges off the U.S. West Coast

 

 

Abstracts

The HERMES project

(Hotspot Ecosystem Research on the Margins of European Seas)

Phil Weaver

Southampton Oceanography Centre, UK

 

Europe’s deep-ocean margin stretches over a distance of 15,000 km along the Atlantic ocean from the Arctic to the Iberian margin and from western to eastern Mediterranean, through to the Black Sea. The margin extends from the shelf edge at about 200m depth down to c.4000m depth where the abyssal plain or oceanic basins begin, covering 3 million km2 – an area about one third of that covered by Europe’s landmass. Most of this deep-ocean frontier lies within Europe’s Exclusive Economic Zone (EEZ) and is therefore of direct interest for the exploitation of biological, energy and mineral resources.  A major aim of European policy is to develop these resources in an ecologically sustainable manner. This requires a profound knowledge of ocean margin ecosystem structure and dynamics considering the variety and complexity of the continental margin environments, which hold deep-sea corals, chemosynthetic life, and more or less specialised fauna in canyons. The HERMES project will address these issues by investigating some of the more important “hotspot” ecosystems in a coherent manner, integrating research on biodiversity and biological processes intimately with the physical factors controlling ecosystems (geology, sedimentology, physical oceanography, biogeochemistry).  In addition, we will set present-day ecosystems in an historical framework by studying the sediment record to determine long-term environmental changes and the potential response of ecosystems to global change over decadal to millennial scales.

 

Our “hotspot ecosystems” include cold-water corals, canyons, cold seeps and anoxic ecosystems as well as some aspects of the open slope environments between the hotspots.

Figure 1: Map showing the HERMES study areas.

Large open circles indicate specific study sites.

 

Cold-water coral ecosystems

The colonial stone corals Lophelia pertusa and Madrepora oculata occur on the deep shelves along 4500 km of the northwestern European continental margin, and in Scandinavian fjords. The intense calcification of the coral colonies enables them to provide a three-dimensional complex habitat for a vast number of associated species that live within or alongside the coral ecosystem. With this large latitudinal spread of the coral ecosystem, we can analyse ecosystem response to different trophic regimes, comparing seasonally eutrophic, high latitudinal settings with more meso- to oligotrophic sites further south in the NE Atlantic and the Mediterranean Sea. These comparative studies will be carried out by assessing biodiversity trends (taxonomy and molecular genetics) and trophic food webs (biochemistry).

 

Site-specific life history studies will be performed on the coral skeletons using environmentally sensitive trace elements and stable isotopes. In order to define the physical forcing factors and the quality and quantity of carbon-flux rates, targeted long-term experiments using benthic landers equipped with CTD-probes, ADCPs, current meters, particle traps and time-lapse cameras will be deployed in a number of hydro-acoustically mapped and ROV-inspected coral sites. In some locations cold-water coral associations thrive in close vicinity to hydrocarbon fluid flow environments, such as in or near active pockmarks on the Norwegian Shelf, or on the flanks of mud volcanoes in the Gulf of Cadiz. These areas are prime sites for addressing whether coral communities are associated with seabed geosphere processes.

 

The aims of our study are to understand the structure, functioning and dynamics of deep-water coral ecosystems under different trophic regimes and under different climatic settings. We will investigate the change of biodiversity which affected deep-water coral ecosystems during the last glacial-interglacial cycle and forecast how the ecosystem will react to future environmental change. The links between deep-water circulation patterns and the likely geosphere-biosphere coupling of deep-water coral ecosystems in hydrocarbon provinces will be studied. The overall aim is to analyse and minimise the negative impacts of human activities on deep-water coral ecosystems through provision of mitigation options, risk assessments and recommendations for management and conservation.

 

Canyon ecosystems

Canyons were chosen as a focus for HERMES because they are key environments on the continental margin that are affected by dynamic geological and physical oceanographic processes.  These processes regulate the distribution and the diversity of the fauna in a number of different ways, offering valuable comparisons to open slope environments.  Canyons are hotspots of biodiversity, major pathways for the transportation and burial of organic carbon, and fast-track corridors for material transported from the land to the deep sea.  Canyons act as temporary buffers for sediment and carbon storage.  However, rapid, episodic flushing of canyons may mobilise large amounts of sediment, carrying it to the abyss and annihilating benthic ecosystems over a wide area.  The frequency of these potentially catastrophic events and the fluxes of particles produced are largely unknown, as are the rates of recolonisation and restoration of the canyon ecosystems.

 

Our view of biological processes in canyons has changed considerably in the last few years because of the increased use of submersibles and ROVs. The results indicate the importance of various zooplankton groups acting as a link to fish and mammal populations. The species and their abundances differ from canyon to canyon and appear to be related to downward particle fluxes, topography and the hydrographic features of individual canyons. Canyons appear to be important in the channelling of macrophyte debris, which may have a significant effect on the relative abundance of some species.   Few studies of the chemistry of canyons have been carried out, even though canyons play a crucial role in the redistribution of carbon and anthropogenic materials derived from marine primary production and terrestrial runoff. Because canyons channel and focus sediment distribution, anthropogenic tracers are relatively high in relation to surrounding slope areas. Canyons are being considered as potential disposal sites for various wastes, including carbon dioxide. These plans assume that canyons are isolated from the adjoining continental slope. We will test this assumption and determine the degree of interconnectivity between canyons and the open slope.

 

The aim, of our canyon studies is to compare and contrast key canyon systems distributed along the European Atlantic and Mediterranean ocean margins. We will do this by comparing the species richness and community structure of benthic communities both within and between canyons and relate these to environmental factors: physical (e.g. current regime), geological (e.g. sediment transport and grain size) and biogeochemical (input of organic matter and pollutants). We will determine whether canyons act as refugia, for instance as areas for fish aggregation and spawning, and whether they act as larval sources and sinks for other ocean margin ecosystems, including deep-water corals. In addition, we aim to determine why only some canyons act as feeding grounds for cetaceans. The overall aim is to provide the scientific context for broad management plans for European canyon systems. This is important in habitat conservation, the potential disposal of carbon dioxide, fisheries management, and in assessing the long-term effects of materials derived from terrestrial run-off that are transported to deep water by canyons.

 

Cold seep ecosystems

Cold-seep ecosystems have only recently been discovered on European margins where they occur in a variety of geological settings, including mud volcanoes, pockmarks and gas hydrates outcrops. The interplay between sea floor methane fluxes, other chemical compounds and sediment microbes favours carbonate precipitation and colonisation of these habitats by exceptionally rich benthic communities fuelled by chemical energy. These dense and endemic communities rely mainly on symbiosis with chemotrophic bacteria that produce large amounts of organic carbon through chemosynthesis. The presence of these unique ecosystems in regions of low animal density highlights the crucial role of local resource enrichments on benthic community composition and productivity.

 

To increase our understanding on the structure and dynamics of seep communities, we need to answer several questions including: how do environmental factors influence community structure? What are the chemical fluxes at the sediment interface? What are the interactions between abiotic and biotic factors? What is their role in substratum modification? The functioning and dynamics of such ecosystems and their role on earth climate and in element cycling are mostly unknown and are also important questions to address. Knowledge of the global carbon balance is incomplete without a systematic consideration of the amount of carbon cycled through biological processes. Until recently, the oceans were regarded primarily as a carbon sink, but the emerging role of the oceans as a source through methane advection has become an important research topic. Methane is an important greenhouse gas and understanding the interaction between physical, geological and biological regulation mechanisms for methane is critical for predicting climate change.

 

Anoxic ecosystems

Microbes occur in every niche in the ocean and comprise a significant part of the global biomass. In some continental margin ecosystems they dominate life almost exclusively, generating a great diversity of bacteria, archaea and some single cell eukaryotes. Natural chemical laboratories occur in areas of subsea discharge of fluids and gas (e. g. methane).  These microbial communities and their symbiotic associates are nourished by the chemical energy rising from these sources and form the basis of cold seep ecosystems. These often take the form of dense and endemic benthic communities, in which the high production of organic carbon sustains large size or typical animals and very high biomasses. In high methane flux areas, the benthic biomass produced through chemosynthetic processes can be 1,000 to 50,000 times greater than the biomass resulting from photosynthetic production. The remarkable abundance of specialised invertebrates like giant tube worms or bivalves is one of the most striking features of seep communities and one of the best ‘indicators’ of fluid emission at the sea floor.

 

Systems such as gas chimneys, pockmarks and mud volcanoes in the Black Sea, Eastern Mediterranean, Gulf of Cadiz and the Norwegian margin represent distinct geological structures which are excellent target areas for our research. Recent geomicrobiological research provides evidence for a variety of these ecosystems holding a great diversity and biomass of bacteria and archaea.

 

The main questions to be addressed in HERMES include: 1) What are characteristics and driving forces of active geological structures harbouring anoxic microbial ecosystems? 2) Are there unique key microorganisms and biogeochemical pathways involved in this biosphere-geosphere coupling? 3) What is the resilience and response to external forces and global significance of these geo-ecosystems?

 

Open slope ecosystems

There is increasing evidence that continental slope ecosystems around Europe represent one of the major repositories of all marine biodiversity. However, although local diversity is moderately well documented for certain taxa at certain sites, very little is known about diversity at large spatial scales. If the distribution of biodiversity on continental slopes is far from being clarified, our comprehension of the mechanisms driving biodiversity attributes and distribution is even more uncertain. Convincing evidence exists that small-scale patchiness permits a large number of similar invertebrates to coexist by specialising on different types of patches or different successional stages. However, depth and latitudinal patterns in diversity that have been previously described for different taxa are often contradictory and whether this variation reflects geographic variability or differences in the responses of taxonomic groups is far from clear. We still need to identify major factors/processes such as gradients of productivity, oxygen availability, sediment heterogeneity, grain size, mineralogical composition and hydrodynamic forcing as well as past and present disturbance events expected to control biodiversity production and accumulation at large spatial scale. Understanding the role of these factors is of paramount importance for predicting the effects of global changes on biodiversity and ecosystem functioning in the deep seas and for identifying strategies for the sustainable use of the deep-sea resources along Europe’s margin.

 

Our aim is to understand the environmental and biotic factors influencing biodiversity (species richness and community structure) on European continental margins. In particular, we will address why biodiversity should apparently be greatest at mid-slope depths. Geological disturbance by events such as landslides will be investigated. The research will involve biologists, sedimentologists, physical oceanographers and biogeochemists. In addition, the pan-European operations of HERMES will be used to determine the ranges of key species along the ocean margin and in relation to physical oceanographic and topographic boundaries.

 

HERMES Geographic Information System (GIS)

The project will collect a large amount of spatial data and draw heavily on existing datasets. All this data will be collated into a GIS package to provide for the first time an environmental database covering the entire European ocean margin. The HERMES GIS will include: an inventory of margin hotspots together with integrated sea floor maps at various scales and resolutions using state-of-the-art techniques and technology, including deep towed sidescan sonars, sub-bottom profilers, ROV and AUV mounted multibeams and camera systems. Recent advances in deep-water positioning systems now enable the acquisition of geo-referenced data gathered at a variety of scales (ranging from regional down to visual) and for them to be fully integrated in a GIS environment. The HERMES GIS will also include spatial and temporal hydrographic data enabling visualisation of watermass distribution and circulation patterns. The likely changes in hydrographic conditions at hotspots, related to changes in thermohaline circulation resulting from different global change scenarios proposed by Earth System Science models, will be constrained. Parameters identified as ecosystem drivers will then be input into simulations to forecast local ecosystem responses to global change using the inverse mass balance models developed elsewhere in the project.

 

Modelling and Policy Advice

The project extends beyond the basic research, mapping and habitat classification into ecosystem modelling and policy advice. The modelling is aimed at improving our ability to forecast the effect on ecosystems of natural and anthropogenic perturbations. The results of the modelling will serve to explore the effects on the ecosystems of natural and anthropogenic impacts.

 

Finally, we will attempt to integrate the scientific output of the project with socio-economics and legal research to underpin the development of a comprehensive European Ocean and Seas Governance strategy. It will be the first time that such an approach has been adopted on a pan-European scale for the deep sea. The intended outcome is to develop concepts and strategies for the sustainable use of offshore marine resources, while taking into account the negative impact of human activities.

The project began on the 1st April 2005 and will run for 4 years.

 

Habitat mapping and national sea floor mapping strategies in Canada

R. A. Pickrill and V. E. Kostylev

Geological Survey of Canada (Atlantic), Dartmouth, NS, Canada

 

As the twentieth century drew to a close Canadian ocean management policy and the supporting marine science within the federal government was entering an exciting new era. Competition for declining offshore resources, fishery collapse, and mounting public pressure for improved management, led the federal government to enact Canada’s Ocean Act. This visionary legislation lays the framework for precautionary, sustainable management of our offshore lands; encapsulating the principles of conservation and ecosystem based management, and laying the foundation for systematic habitat mapping.

 

Management of offshore lands has been constrained by a lack of high quality information on marine ecosystems. However, converging technologies of GPS and multibeam mapping demonstrated the benefits of the new sea floor mapping technology, and led to the development of a proposal for a national program to map Canada’s offshore lands. SeaMap, an interdepartmental initiative would establish standards and set national priorities for sea floor mapping. The program is yet to be funded. But, the SeaMap proposal demonstrated a need and many of the underlining principals are guiding sea floor mapping and research directions within Natural Resources Canada and the Department of fisheries and Oceans over the ensuing years.

 

In 2002 research in NRCan was reorganised to improve alignment with government priorities; the resulting Geoscience for Ocean Management Program (GOM, www.gom.nrcan.gc.ca) acknowledged the role that sea floor mapping can contribute to habitat mapping and environmental stewardship. With one of the largest offshore territories, a relatively small population base, and a severe marine environment, Canada faces challenges to implement integrated and sustainable management of our offshore lands. Through a series of stakeholder workshops priority areas of national importance have been identified, while a habitat mapping strategy has been developed to optimise program outputs.

 

Three systematic approaches to habitat mapping have been developed;

1.      High resolution regional mapping of seabed geology and habitats, based on acoustic surveys and groundtruthing (e.g. fishing banks)

2.      Targeted high-resolution mapping of seabed features of value for conservation and fishery, and impacted marine habitats (e.g. sponge reefs, dump sites)

3.      Broad-scale habitat mapping based on deterministic modeling of geological and oceanographic controls on benthic fauna (e.g. shelf-wide mapping) and extrapolation of local models to regional applications (e.g. Beaufort Sea habitat mapping).

 

The model applied in a particular project being defined by geographical extent, ability to collect new data, environmental constraints, the time frame and stakeholder needs, yet always building toward a national framework.

 

Recent applications of geological information in the selection of candidate marine protected areas in Australia

Peter T. Harris

Marine and Coastal Environment Group, Geoscience Australia

 

Management of the marine environment in Australia’s EEZ is addressed by an Oceans Policy that was declared by the government in 1998. The Policy is being implemented through the generation of a series of regional marine plans (RMPs), followed by the selection of a network of representative marine protected areas (MPAs). The MPAs have multiple goals including fisheries management and the conservation of marine biodiversity. The southeast region of Australia has been the first part of the EEZ to undergo the RMP (in 2003) and MPA selection processes (currently in progress).

 

Abiotic geoscience information has been used extensively to provide crucial supporting information in these processes, to characterise habitats, bioregions and inform managers of the “representativeness” of different proposed MPA candidates. MPA candidates are first presented to stakeholders as “broad areas of interest” (BAOIs) that contain a representative suite of habitat types and include any rare or irreplaceable habitats. These are then reduced in area and borders are negotiated through stakeholder consultation supported by a scientific reference panel. The SE region contains 11 BAOI’s and so far stakeholder negotiations have been completed and MPAs nominated for two of these. In the deep-water, continental slope and abyssal areas, an interpreted map of 21 categories of different sea floor geomorphic features was used as a proxy for habitats. On the continental shelf, a “seascape” map (eg. Roff et al., 2003, Marine and Freshwater Ecosystems, 13(1): 77-90) was produced using multivariate analysis, which incorporated geomorphic features, water depth, tidal bed stress, wave-induced bed-stress, sediment grain size, sediment carbonate content, gravel content and mud content.

 

GIS analysis shows that the 11 broad areas of interest (BAOI) capture a representative sub-set of the geomorphic features that occur within the SE region. The two MPA’s, however, do not contain all of the feature types found within the larger BAOI. Similarly, the shelf seascapes contained within the BAOIs capture a representative sub-set of those that occur within the SE region. This experience has demonstrated that GIS analysis of abiotic data is an essential, valuable tool for selecting representative MPAs throughout the process of MPA network design and stakeholder consultation.

 

Video and multibeam observations of mega-benthic habitats in the Rockall Trough, Irish continental margin using a remotely operated vehicle; implications for managing deep-sea habitats

Janine Guinan1, Anthony Grehan1, Karine Olu-Leroy2, Margaret Wilson1, Colin Brown1

1) Department of Earth and Ocean Sciences,

National University of Ireland, Galway, Ireland

2) IFREMER, DRO-EP, Plouzané, France

A quantitative understanding of biological assemblages is a prerequisite to implementing sampling strategies and managing habitats. The management of vulnerable deep-sea habitats is important as human activity at continental margins increases e.g. deep-sea fishing, telecommunications cable routing and oil exploration.

 

Geo-referenced videographic datasets were collected during the first year of scientific use of the French remotely operated vehicle (ROV) Victor 6000 in the North East Atlantic. The main purpose of the cruise was to investigate carbonate mound structures (2-3 km in diameter rising 300 m above the seabed) and deep-sea coral communities previously identified in sonar records. Here we examine video datasets from ROV dives conducted in the SE and SW Rockall Trough, west of Ireland between depths 620-885 m. Multibeam data recently acquired by the Irish National Seabed Survey provided the regional bathymetry for the study locations.

 

A technique for the quantitative analysis of video datasets in deep-water surveys has been developed to study patterns of megabenthic habitats and deep-water corals, in particular the scleractinian coral Lophelia pertusa. Results of first trials of the SEABAT 8101/240khz multibeam system micro-bathymetry acquired with the Victor ROV are also presented.

 

Biological assemblages tend to exhibit significant change along physical (environmental) gradients in the deep-sea. These gradients include bathymetric relief, substrate type and hydrography. We have investigated quantitatively the hypothesis that cover of Scleractinian coral exhibits variability in relation to some or all of these environmental gradients at the scale of 10s of kilometres.

 

The coral cover variation was investigated (I) among transects within sites and (ii) among transects between sites. Distinct vertical patchiness was observed on carbonate mounds with dense coral cover associated with mound summits. The inter-mound seabed is characteristically depauperate of coral assemblages. Results show that mound summits occurring at similar depths at two sites exhibit variability in coral cover. One possibility is that the extent of this coral cover is related to increased current acceleration in the SW Rockall Trough.

 

Deep-water ROV surveys for scientific research can be costly and time consuming. A better understanding of the distribution of biological assemblages in relation to seabed morphology will greatly assist in constraining ROV survey planning and design to optimise vehicle bottom time.

 

Thematic maps for coastal planning

Oddvar Longva, Kari Helene Andresen, Ole Christensen,

Terje Thorsnes, and Aave Lepland

Geological Survey of Norway, Trondheim, Norway

 

Through the HASUT project a small area on the coast of Norway was mapped in detail regarding bathymetry, surface geology and biological diversity. This work is taken further as a Pilot study for Coastal Zone Management in the Aquareg Programme under the EU-programme INTERREG IIIC. The objective is to develop the “best practice” for management of the coastal zone, focusing on the development of aquaculture and coastal fisheries in Ireland, Spain and Norway. The pilot study will develop a suite of thematic maps for web-publication. Among the actual themes are depths, sediments, including properties like currents, deposition/erosion, anchoring and habitats. A first version of these maps will be presented.

 

The new British Geological Survey marine and coastal mapping

project: Recent progress

Alan Stevenson

British Geological Survey, Murchison House

 

The British Geological Survey has recently merged its marine, coastal and hydrocarbons research activities. The programme for the next 5 years will focus on delivering 3D mapping and modelling using multibeam and other high-resolution data that will address key questions related to the impacts of climate change and societal developments and will provide information required to define habitats, marine resources and conservation areas.

 

The proposed work is subdivided into four settings; estuaries and associated alluvium; open coast from the back of beach or cliff to wave base; continental shelf from wave base to shelf break and continental margins from the shelf break to deep-ocean base of slope. Data acquisition will concentrate on areas identified by stakeholders as being of importance to the UK science community, industry or marine managers. In particular, gaps in previous BGS reconnaissance mapping of the shelf areas include the coastal zone (to about 10m water depth), which now faces the most immediate pressures for environmental management and requires data for integrated coastal zone management. The coastal terrestrial, littoral and shallow marine settings exhibit high biodiversity, but because of the difficulties in charactering them, the extent and health of resources are poorly documented. Seabed sediment facies largely define the distribution of breeding, nursery and feeding grounds of many key species and, with additional turbidity and energy regime data, largely define nearshore marine landscapes.

 

The results of recent surveys in the nearshore zone and future plans will be presented at GeoHab 2005.

 

A quantitative approach for using multibeam sonar data to map benthic habitats

Curt E. Whitmire1, Robert W. Embley2, W. Waldo Wakefield1,

Susan G. Merle3, and Brian N. Tissot4

1) NOAA Fisheries – Northwest Fisheries Science Center, WA, USA

2) NOAA – Pacific Marine Environmental Laboratory, WA, USA

3) Cooperative Institute for Marine Resource Studies – Oregon State University, OR, USA

4) Washington State University Vancouver – Program in

Environmental Science, WA, USA

 

Dramatic declines in several species of demersal fishes off the U.S. west coast have resulted in the designation of eight commercially important species as being overfished. While the causes of those declines are not clearly understood, the fact remains that there is a dearth of abundance data for many groundfish species. One challenge in designing a systematic survey is that many species associate with heterogeneous substrata of varying relief. In many areas, the rugged sea floor topography precludes sampling by conventional techniques (e.g., bottom trawl). This has stimulated research that characterizes fish-habitat associations for the assessment of demersal fish species and the design of new survey methodologies.

 

Using spatial analytical techniques and a combination of data from remote sensing and in situ observations, three benthic habitat classes were mapped for a large rocky bank off the central Oregon coast known as Heceta Bank. Observational data from remotely operated vehicle (ROV) dives in 2000 and 2001 were used to establish habitat classes with seabed characteristics that have been statistically shown to correlate with demersal fish distributions. The observational habitat data were then extrapolated over the extent of a multibeam sonar survey conducted in 1998 using quantitative parameters derived from high-resolution bathymetric and acoustic backscatter imagery. The resultant map shows the predicted extents of three habitat classes: Rock Outcrop (high vertical relief)Boulder/Cobble (high acoustic reflectivity), and Mud/Sand (unconsolidated).

 

Groundfish distribution and bottom type in Hecate Strait and Queen Charlotte Sound

Alan Sinclair1, Kim Conway2, Vaughn Barrie2, and Rick Stanley1

1) Fisheries & Oceans Canada, Pacific Biological Station, Nanaimo, BC, Canada

2) Geological Survey of Canada (Pacific), Sidney, BC, Canada

 

Associations between groundfish species spatial distribution and the surficial geology of Hecate Strait and Queen Charlotte Sound off the west coast of Canada were examined. The fish distributions were derived from commercial bottom trawl and research trawl survey catches. The species list includes elasmobranch, gadid, rockfish and sole species. The species distributions are overlaid on maps of surficial geology determined from seismic profiles, sidescan sonar, sediment samples and core samples. Five geological units have been determined, including bedrock, till, mud, and sand and gravel. These units are subdivided further. Associations between fish distributions and geology were examined using contingency analysis and ordination techniques.

 

Three main fish/surficial geology groups emerged. One consisted of species with relatively shallow depth distributions over thick transgressive sand and gravel bottom types or thin sand and gravel over bedrock. The species included big eye skate, spotted ratfish, English sole, Pacific cod, lingcod, Pacific halibut, petrale sole, and rock sole. A second group included species with slightly deeper depth distributions over a broader range of bottom types with more mud and less transgressive sand and gravel. The species in this group included arrowtooth flounder, long nose skate, spiny dogfish, Dover sole, rex sole, and sablefish. The third group included rockfish species with depth distributions overlapping the second group. The surficial geology was dominated by relatively hard till, bedrock, and transgressive sand over bedrock, with varying degrees of mud.

 

The associations between species distributions and surficial geology are confounded by depth. The geology is dominated by trangressive sand and gravel at depths up to 125 m while muds dominate at depths over 200 m and there is a clear progression between these dominant bottom types at intermediate depths. Individual species also occupy specific depth ranges. Species distributions by both depth and bottom type were further examined to identify species which simply occupied the available bottom types and those which selected specific bottom types.

 

Benthic habitat mapping prior to removal of the Elwha Dam; preparing for change

Guy Cochrane, Jonathan Warrick, and Jodi Harney

Coastal and Marine Geology Program,

U.S. Geological Survey, California, USA

Two dams on the Elwha River of the Olympic Peninsula are currently slated for removal in early 2008. Dam removal will expose more than 14 million cubic meters of mixed grain-size sediment deposited in the reservoirs behind the dams, which will erode naturally and be transported to the Strait of Juan de Fuca. Increased sediment supply to the Strait may mitigate the current erosional trend along the river delta and adjacent shoreline. Removal of the dam should improve spawning for native salmon. A preliminary map of sea floor-sediment texture, derived from recently collected sonar, video, digital bed sediment images, and grab samples shows the area offshore of Elwha River mouth is dominated by coarse sediment, ranging in size from sands to boulders. Increased fine-grained sediment supply may bury or alter these nearshore habitats for locally productive kelp beds and geoducks.

 

Application of seabed character interpretations to broad scale habitat mapping: A case study from the eastern English Channel

R. Coggan1, S. Philpott2, D. Limpenny1, W. Meadows1, S. Birchenough1 and S. Boyd1

1) The Centre for Environment, Fisheries and Aquaculture Science, UK

2) British Geological Survey, UK

 

Seabed character maps provide a potentially valuable starting point for mapping seabed habitats, as they delineate distinct areas such as gravel banks or sand wave fields that can then be targeted for ground truth sampling to determine the composition of their biotic communities. As such, they are a useful approach to assessing the impacts of aggregate dredging operations at the site-specific level, and for placing these in context over a broader spatial scale. Seabed character maps are normally derived by interpreting a sonar mosaic constructed from adjoining, parallel sidescan survey tracks. The mosaics contain a great deal of detail, and while this is appropriate for the high resolution mapping required at site-specific levels (up to ~50 sq km), it is somewhat excess to requirement for lower resolution mapping at larger spatial scales (around 500 sq km). This implies that significant cost savings can be made when mapping broad scale areas if a survey strategy can be identified that will deliver reliable seabed character maps based on less that 100% sidescan coverage.

 

We surveyed a 600 sq km area of the eastern English Channel, to build a series of sidescan lines representing progressively greater density of sidescan coverage (closer track spacing) and used subsets of these lines to produce interpolated seabed character maps based on 4 km, 2 km and 1 km track spacing. A fourth map contained a central corridor where full coverage (100%) had been achieved. The suitability of the maps for broad scale surveys was assessed by comparing their relative accuracy and precision. Maps based on 4 km and 2 km line spacing failed to identify some significant seabed regions that were apparent on the map derived from 1 km line spacing. This latter map represented a 50% density of sidescan coverage, and the delineations of seabed regions in the central corridor were only marginally improved by the availability of 100% coverage. It was concluded that 50% coverage, equating to 1 km line spacing, was the most cost-effective strategy for mapping broad scale areas.

 

Ground-truth samples collected during the sidescan surveys were used to validate the seabed characterisations and provide information on the distribution of benthic fauna. Direct observations, made with a towed camera sledge, showed seabed characters consistent with expectation. Sediment samples from Shipek and Hamon grabs confirmed the general substrate type, although the Shipek grab appeared to under sample the coarser elements of the sediment. Benthic infaunal communities (sampled by 0.1m2 Hamon grab) tended to map more closely to sediment type and seabed character than epifaunal communities (sampled by 2-metre beam trawl). The study provides guidance for the application of seabed character interpretations to broad scale habitat mapping that will be of benefit to marine spatial planning and resource management.

 

The use of habitat mapping tools in the assessment of the re-habilitation of the seabed following marine aggregate extraction

D.S. Limpenny, S.E. Boyd, K.M. Cooper, and W.J Meadows

The Centre for Environment, Fisheries and Aquaculture Science, UK

 

The commercial extraction of marine aggregates in the U.K. began in the 1960s and peaked at around 23 million tonnes per annum in 1989. Since then, the quantities removed from the seabed have remained relatively steady. Public concern regarding the potential environmental impacts of this activity has grown in recent years, particularly in light of proposed extraction activity in the eastern English Channel. Previous research on rates of rehabilitation of seabed habitats has focused more on short-term experimental studies rather than longer-term recovery of commercially dredged sites. Therefore, there is limited information that is directly applicable to the impacts of commercial dredging operations in U.K. waters, where the lifetime of a typical production licence is at least 15 years.

 

This research was undertaken to assess the status of the seabed sediments and associated benthic fauna within and outside areas where dredging had ceased, and to conduct follow up sampling to monitor progress towards physical and biological ‘recovery’. Annual surveys were conducted between 2000 and 2003 at 4 relinquished extraction sites which provided a range of dredging histories and environmental settings for investigation during this study. These investigations used a combination of acoustic mapping (sidescan sonar, swathe bathymetry, acoustic ground discrimination) photographic and biological sampling techniques to assess the rate and degree of physical and biological recovery at a number of relinquished aggregate extraction sites around the English coastline.

 

This research has improved our understanding of the ecological effects of marine aggregate extraction in U.K. waters and has also allowed an examination of the likely factors responsible for observed differences in the recovery of U.K. extraction areas. The study was able to refine our understanding of the recovery process and offered the following key conclusions:

•       The physical effects of dredging can last for more than 10 years after the cessation of the activity.

•       The fauna within areas exposed to high levels of dredging can remain in a perturbed state for at least 7 years after dredging has ceased.

•       In general, sediments and fauna collected within areas exposed to high levels of dredging were more variable than those collected in other areas and this may be a symptom of perturbed conditions.

•       It is likely that dredging intensity, or an associated variable, is an important factor in determining the nature of succeeding benthic assemblages.

•       The geographic location of the extraction sites and the percentage of sand at the seabed within the sites explained regional differences in the fauna, and consequently the results tend to be site specific.

 

This work was funded by the Department for Environment, Food and Rural Affairs, the Office of the Deputy Prime Minister and The Crown Estate and forms part of a wider portfolio of related research projects undertaken by CEFAS.

 

Eastern English Channel large-scale seabed habitat maps:

Helping to support the sustainable management of offshore resources

S.L. Philpott1, J.W.C. James1, K.L. Howell2, C.M. Johnston2,

D.S. Limpenny3, J.E. Robinson4 and N.M. Simpson4

1) British Geological Survey, UK

2) Joint Nature Conservation Committee, UK

3) Centre for Environment, Fisheries and Aquaculture Research, UK

4) Marine Ecological Surveys Ltd, UK

 

This paper describes a 3 year programme which aims to provide integrated broadscale habitat maps in support of the sustainable management of offshore resources. The study covers approximately 4500 km2, within the central part of the Eastern English Channel. It is the intention of the study, which is in its initial stages, to produce habitat maps based on an inter-disciplinary approach, integrating geological, geophysical and biological data and interpretations, including new surveys using modern high resolution geophysical systems, ground truthed with sampling and video.

 

The immediate driver is the discovery of substantial aggregate resources in this area and the requirement to manage the sustainable development of this resource and minimise potential impacts. The area of resource also needs to be assessed within the broader context of the Eastern English Channel.

 

The project surveys and maps will allow us to distinguish between the habitats within this area, and therefore contribute to managing the whole resource sustainably, including considering parts of it for designation as Special Areas of Conservation (SACs) under the European Habitats Directive, and parts which may be suitable for resource exploitation. The project will also contribute towards improving the offshore sections of both the U.K. Marine Habitat Classification System (Conner et al., 2004) and the European Habitat classification system (EUNIS), through providing good quality epifaunal and infaunal data from a currently data poor habitat type. The project also aims to contribute to issues such as predicted impacts within the aggregate licence areas and their significance in a wider context. These issues can only be addressed with a knowledge of the resources, habitats and communities of the wider Eastern English Channel with which to compare those of the licence areas.

 

The primary output from this project will be the production of the first habitat and biotope maps for the Eastern English Channel. Using GIS to integrate the maps, this information will be used to identify and quantify the species and habitats, of both conservation and fisheries importance, that exist within the area and assess their significance in a wider regional context. All marine stakeholders will benefit from an opportunity to use these maps and associated survey data.

 

Variation of physical environments and habitats in the Hudson River Estuary

F.O. Nitsche1, R.E. Bell1, S. M. Carbotte1, W.B.F. Ryan1, A. Slagle1, and R. Flood2

1) Lamont-Doherty Earth Observatory of Columbia University, NY, USA

2) Marine Science Research Center Stony Brook University, NY, USA

 

As the human population of the planet moves towards coastal cities, major estuaries are crucial resources for transportation, commerce, and industrialization. To effectively manage these crucial resources detailed knowledge of the physical environment and habitats in estuaries is essential. Aiming to implement a science based management policy for the Hudson River Estuary the New York State Department of Environmental Conservation (NYSDEC) launched the Hudson River Estuary Benthic Mapping Project as part of their Hudson River Estuary Program.

 

As part of this project we have mapped the entire 240 km long Hudson River Estuary with the exception of several very shallow (<2 m) embayments. We have acquired full coverage high-resolution multibeam bathymetry and backscatter, as well as sidescan sonar data, both with <1 m resolution. Simultaneously, a dense network of sub-bottom profiles was acquired with line spacing of 80 m and 160 m in N-S and E-W directions respectively. In addition, we took over 400 sediment cores and 600 grabs to provide ground truth of the acoustic data and obtain detailed information on sediment lithology, physical properties and texture.

 

Integrating the different data sets using a Geographic Information System resulted in comprehensive and detailed substrate information. We created detailed maps of morphology, grain size distribution, and process-related sedimentary environments such as deposition, erosion/non-deposition, or sediment waves. The sediment grain size in the lower, marine-influenced part of the estuary is dominated by silt and clay; whereas the upper, fresh water dominated part of the estuary yields mainly sandy sediments. Local effects such as the contribution of tributaries, winnowing, and low-flow embayments modify this general pattern. In contrast to the grain size, the sedimentary environments vary strongly throughout the estuary. Although there is a local dominance of deposition at the estuarine turbidity maximum, there are usually large variations across the estuary. These variations most likely reflect differences in current strength, wave exposure, and morphology.

 

Although we have a good knowledge of the substrate as result of the benthic mapping, linking the different environments to actual habitats remains difficult. The differences in salinity result in different communities and make it difficult to apply a classification scheme entirely based on one acoustic data set to the whole system. High turbidity of the estuarine water makes it difficult or impossible to use standard biological investigations with divers, video, or photos to map distributions and composition of communities. Instead, we are using benthic samples from sediment grabs, observations from fishing, and sample catch studies by state and federal agencies.

 

The Outer Bristol Channel marine habitat study:

Interim results

J.W.C. James1, S.L. Philpott1, G.O. Jenkins1, A.S.Y. Mackie2,

T. Derbyshire2 and E.I.S. Rees2

1 British Geological Survey, Nottingham, UK

2 National Museums & Galleries of Wales, Cardiff, UK

3 University of Wales, Bangor, UK

 

The Outer Bristol Channel Marine Habitat Study has been designed to produce baseline biological and geological data, for an area of approximately 2400 kmwithin the Bristol Channel, through an integrated survey programme.

 

A number of geophysical and biological sampling cruises have been undertaken. Equipment utilised includes multibeam, digital sidescan sonar, surface tow boomer. The results from the geophysical interpretation have been ground truthed by sea bed videos, photography and sampling. In total, 3000 line kilometres of multibeam data (including repeat lines), 1900 km of sidescan data, 150 km of surface tow boomer data and samples at 147 locations have been acquired. Videos at 12 locations across the study area have also been acquired.

The project is scheduled for completion in March 2006. The presentation gives an update on the progress to date and presents some of the interim results.

 

Benthic habitat mapping in Newman Sound – A Newfoundland Fjord

Alison Copeland1, Trevor Bell1, Evan Edinger2, John Shaw3, and Robert Gregory4

1) Department of Geography, Memorial University of Newfoundland, Canada

2) Departments of Geography and Biology, Memorial University of Newfoundland, Canada

3) Geological Survey of Canada – Atlantic, Bedford Institute of

Oceanography, Dartmouth, NS, Canada

4) Department of Fisheries and Oceans, St. John’s, Canada

 

This paper presents the results of a project to map the benthic habitats of Newman Sound, a fjord in eastern Newfoundland, Canada. The primary goal of the project was to assess the effectiveness and efficiency of using multibeam sonar to map habitats and biodiversity in a fjord environment. This assessment was carried out by groundtruthing the mapped multibeam backscatter and bathymetry. Newman Sound is a 32km long fjord divided into two basins by a shallow (11m deep) sill. Hydrography and the shape of the fjord suggest that circulation is primarily tidal, and the tidal range is 1m. Water temperatures are cool year round due to the influence of the Labrador Current; the fjord therefore contains a mostly boreal marine fauna with several arctic species.

 

Groundtruthing was conducted by collecting video imagery and benthic grab samples. These were combined with previously drawn maps and geophysical data to characterise benthic substrates and biota. Benthic grab samples were collected at 56 stations at water depths ranging from 4 to 312m. Video images were collected in shallow water using a drop camera (18 stations) and SCUBA video transects (9 stations). In deeper water (5 stations) an ROV was used. Sampling stations were chosen to represent a variety of backscatter values across a range of water depths.

 

Backscatter data indicated that the floor of the inner sound, a 60m deep basin, was covered by acoustically low reflectance substrate. Video and grab sample analysis showed organic-rich mud dominated by the tube dwelling polychaete Maldane sarsi. Silty mud was also found in large areas of the deep outer basin (maximum depth 320m) with similar backscatter values. This deepwater mud contained less organic material, and was sparsely inhabited by burrowing polychaetes and echinoderms. Bedrock exposed along the fjord showed abundant epilithic fauna, particularly the anemone Metridium senile. These habitats were difficult to sample, and were only represented by 2 video stations. Coarse textured substrates were more difficult to characterise as they appeared in various grain size combinations. These included muddy gravel in deep water (over 150m) with a rich diversity of burrowing and surface dwelling fauna, and shallow water cobble substrate dominated by macroalgae and encrusting fauna. Grab sampling on the inter-basin sill identified a rhodolith bed. This habitat was biologically the most diverse of those surveyed but was not acoustically distinguishable from gravel or cobble habitats.

In Newman Sound multibeam sonar was effective in mapping very low reflectance mud and sand substrates, as well as high reflectance bedrock exposures. Identifying coarse substrates with intermediate reflectance was more difficult, so more extensive groundtruthing in these habitats would be necessary to map them successfully. It is these coarse substrates which commonly contain the highest biological diversity, and therefore are of greatest interest for marine management and conservation.

 

Acoustic seabed classification and mapping of capelin

spawning habitats in coastal Newfoundland

Candace Rose-Taylor1, John T. Anderson2 and Trevor Bell1

 

1) Department of Geography, Memorial University of Newfoundland, Canada

2) Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, Newfoundland, Canada

Historically capelin (Mallotus villosus) spawning in Newfoundland has been reported to occur on and near modern beaches. The only known demersal spawning occurred offshore on the Southeast Shoal of the Grand Bank of Newfoundland. Recently capelin have been observed spawning demersally several kilometers from shore in coastal northeast Newfoundland. These spawning sites are dominated by gravelly substrate, which in part may represent submerged beaches formed ca. 6000-9000 years ago when relative sea level was lower. As part of a multi-disciplinary study into the predator-prey dynamics of demersal capelin spawning in coastal Newfoundland, our goal is to use acoustic techniques to classify and map demersal capelin spawning habitats. In addition, we also intend to reconstruct submerged shorelines as a potential guide to spawning habitat. Normal incidence acoustic data (38 kHz) were collected at several sites where capelin spawning occurred. We used objective classification techniques and seabed bathymetric mapping to characterize capelin spawning habitats. We discuss the utility of these data to map the bathymetry and substrate composition of the seabed and to make predictions regarding potential demersal capelin spawning habitats.

 

Progress in mapping marine benthic habitats in the inland seas of the San Juan Islands, USA and Southern Georgia Strait, Canada – A major international effort

H. Gary Greene1, Vaughn Barrie2, Holly Lopez1, Janet Tilden1,

Charlie Endris1 and Brian Dieter1

1) Center for Habitat Studies, Moss Landing Marine Labs, Moss Landing, CA, USA

2) Geological Survey of Canada, Sidney, B.C., Canada

 

Recent habitat mapping efforts undertaken by the Geological Survey Canada, Pacific and the Center for Habitat Studies of Moss Landing Marine Laboratories has resulted in the comprehensive seafloor coverage of most of the inland seas of the San Juan Islands and southern Georgia Strait. After four years of mapping using the EM1002 95 kHz and EM3000 300 kHz multibeam bathymetric and backscatter data collected by the Canadian Hydrographic Service, we have nearly completed a major regional potential marine benthic habitat map for most of the trans-boundary region of Canada and the USA. This work has led to extensive quantification of habitat types that will be useful in the conservation and management activities of the region. We are presently embarking on documenting the habitat types through in situ observations using ROVs and seafloor sampling. In addition, the geology of the inland sea has been mapped with glacial features, dynamic bedforms and fault ruptured seafloor well defined. We will present seafloor images and interpretive maps that show in detail the complexities and diversity of substrate and morphology that form habitats.

 

Surficial geological habitat map of the Oregon and Washington

continental margin, 2nd Edition

Andrew Lanier1, Chris Goldfinger1, Chris Romsos1, and W. Waldo Wakefield2

1) College of Oceanic and Atmospheric Sciences, Oregon State University, OR, USA

2) NOAA Fisheries, Northwest Fisheries Science Center, WA, USA

 

The development of the Surficial Geological Habitat Map of the Oregon and Washington Continental Margin, created as a part of the Pacific Northwest Groundfish Essential Fish Habitat Project in 2002, was the first comprehensive view of seafloor habitats to be published for the Pacific Northwest region. Time constraints on initial release did not allow for all available datasets to be included. We are currently developing the second release which includes these additional data, and new data collected since 2001. Substantial new data have been collected using the R/V Thompson Kongsberg Simrad EM-300 which operates at a 30 kHz frequency, capable of mapping a range of depths from 5000 to 100m. Along with the addition of the Simrad EM-300 multibeam sonar datasets, the second edition of the Surficial Geologic Habitat Map includes data from a number of other sources including submersible video, sidescan images, and single-beam echo sounder data. The addition of these data sets will allow a much more comprehensive view of sections of the continental margin, with approximately 15% of the area of Oregon continental slope now surveyed using the EM-300 multibeam bathymetric/backscatter sonar. The major benefit from the new data sets is the increase the spatial resolution of the data in those areas to resolutions of approximately 5m in shallow regions (above 150m), to 20-30m in deeper water. The data from those regions are being used to develop a methodology to map rocky habitats on ridge tops of the continental slope. Slope gradients can predict rock outcrop on ridge flanks when ground truthed with direct observations, and this method is currently in use in our maps. In Oregon and Washington, many ridge tops are also rocky, the result of methane seeps that deposit carbonate that is later tectonized to form a high relief rocky habitat. Mapping of these areas is hampered by the lack of modern backscatter data, the only available regional dataset being the 6 kHz GLORIA data collected in the 1980’s. We are calibrating the GLORIA regional data with the new EM-300 backscatter data, submersible video, bottom photos, and core samples to interpret these poorly mapped regions.

 

Geological mapping of the Strait of Georgia:

Application to rockfish conservation and habitat

 

K. Picard1, K.W. Conway1, L. Yamanaka2, L. Lacko2, P. Hill1, J.V. Barrie1

1) Geological Survey of Canada (Pacific), Sidney, BC, Canada

2) Department of Fisheries and Oceans, Nanaimo, BC, Canada

 

Inshore rockfish (Sebastes spp.) stocks, particularly in the Strait of Georgia, B.C., Canada, have shown significant changes in their age structure and populations have been declining for several years. An objective of the Geoscience for Oceans Management program (GOM) of the Geological Survey of Canada (GSC) is producing multibeam bathymetry, backscatter strength, and surficial geology maps of the Strait of Georgia. In collaboration with the Department of Fisheries and Oceans (DFO), this new mapping effort is key to developing new methods of stock assessment for inshore rockfish, enhancing an understanding of fish and habitat associations, and identifying and quantifying rockfish habitats in selected areas.

 

In 2004, 89 Rockfish Conservation Areas (RCA) were implemented along the western Canadian coast, and 44 are in effect in the southern Strait of Georgia. Important elements of the strategy employed in this study are to identify the substrates most utilized by rockfish as habitat based on direct, in situ submersible transect observations.

 

Dive transect results indicate that rockfish are predominately found in bedrock, boulder fields and scarp (slopes greater than 25° from multibeam surface analysis study) environments and these habitats can be readily quantified using acoustic survey results combined with GIS mapping. Initial results show that for three RCAs in Georgia Strait, bedrock covers between 8.5 to 40% of the area, and unconsolidated sediments blanket the remainder. In one RCA a boulder field covers 4% of the surface. The study also shows that between 0 and 28 kilometres of scarps are observed depending on the RCA.

 

By qualifying and quantifying geologically the studied RCAs, we can constrain the potential rockfish habitats that are more likely to protect rockfish. These data can be used to confirm the effectiveness of the existing RCAs and to select new potential conservation areas. This methodology will be applied to selected areas within the Queen Charlotte Basin where surveys, including submersible dives, are planned for May 2005.

 

Using substrate maps for quillback rockfish (Sebastes maliger) stock assessment and management in the southern Strait of Georgia, British Columbia

K. Lynne Yamanaka1, Lisa Lacko1, Jonathan Martin1, Kim Picard2,

Kim Conway2 and Philip Hill2

 

1) Pacific Biological Station, DFO, Nanaimo, BC, Canada

2) Pacific Geoscience Centre, NRCan, Sydney, BC, Canada

 

Inshore rockfish (Sebastes spp.) are targeted by hook and line fisheries throughout the British Columbia coast. Within the Strait of Georgia, catch indices and age data for quillback rockfish indicate that these stocks are at low levels of abundance. Reductions in catch and monitoring programs were implemented for the fisheries in 2002 and research to improve stock assessment and apply fishery closures as a management tool was initiated in 2003. Stock assessment research focuses on developing methods to directly estimate rockfish biomass and work to develop fishery closures has concentrated on the identification of rockfish habitat.

 

Fish biomass estimates traditionally used in stock assessments have not been available for rockfish in British Columbia but new assessment approaches are currently being developed. Similar to assessment work for yelloweye rockfish (Sebastes ruberrimus) in Alaska (O’Connell and Carlile 1993) and for cowcod (Sebastes levis) in California (Yoklavich pers comm), in-situ observations of quillback rockfish were collected in a small study area in the southern Strait of Georgia. The submersible survey was stratified by substrate type, interpreted from geophysical data, and randomly selected dive locations were selected and dives attempted over all substrate types. Within a dive transect, fine-scale (over metres) fish associations with substrate type were observed from the submersible. Quillback rockfish were most frequently observed over bedrock and boulder substrates. Fish densities were determined over a larger scale (100 m2), from observations over entire dive transects within a substrate stratum. Estimates of biomass within the study area were then estimated by applying the large scale substrate specific fish densities to the total area of substrate.

 

Fine scale submersible observations reinforce the strong association of quillback rockfish with specific substrates. The inclusion of these substrates within RCAs is vital to their success in protecting rockfish. Substrate maps enable strategic site and boundary selection of RCAs where available. Within the Strait of Georgia study area, a benthic complexity model, similar to one developed by Ardron (2002) is compared with the substrate map and assessed for its utility in determining suitable rockfish habitat. The complexity model may be useful in developing RCAs, for other areas where no substrate maps exist.

 

Cooperative research and exploration:

Multibeam sonar surveys and habitat mapping of the seafloor within the Cowcod Conservation Areas (CCA), Southern California Continental Borderland

Chris Romsos1, Chris Goldfinger1, Mary Yoklavich2,

Waldo Wakefield3, Jason Chaytor1, Lawrence Hufnagle3, and Mark Amend2

 

1) College of Oceanic and Atmospheric Sciences, Oregon State University, OR, USA

2) NOAA Fisheries, Southwest Fisheries Science Center, Santa Cruz, CA, USA

3) NOAA Fisheries, Northwest Fisheries Science Center, Seattle, WA, USA

 

In cooperation with NOAA Fisheries Southwest and Northwest Fisheries Science Center (SWFSC & NWFSC), the OSU Active Tectonics and Seafloor Mapping Lab conducted extensive shallow-water (<350 m in depth) multibeam sonar surveys of submarine banks including Pilgrim, Kidney, Potato, Cherry, 43-Fathom and Osborn Banks, all within the Southern California Continental Borderland and Cowcod Conservation Areas (CCA). While minimizing mobilization and survey costs, this multidisciplined team shared objectives to: 1) produce high-resolution multibeam sonar bathymetric maps for fisheries research and management; 2) expand the scope of on-going geologic investigations; and 3) test a new water column and bathymetric acoustic mapping system. Direct benefits from an increased understanding of surficial seafloor geology and habitat distributions were realized by fisheries scientists from the SWFSC Santa Cruz Laboratory and University of California, Santa Barbara, who are currently involved in extensive studies of the groundfish and sessile invertebrate populations within this region. These scientists also provided verification (grountruthing) of our habitat interpretations from direct seafloor observations made during manned-submersible dives on these banks. NWFSC personnel provided survey equipment and technical support while taking the opportunity to field test a Simrad/Mesotech SM 2000 in both bathymetry and water column mapping modes. An extension of the cruise for mapping purposes greatly enhanced the scope our geologic investigations in the region and provided a unique chance to explore sparsely mapped areas. The integration of geologic and habitat mapping focused on the vertical tectonics as revealed by low-stand Pleistocene shorelines, which rim all of these banks. The shorelines and faults control the distribution of surface sediments and morphologic elements, and thus are significant to the distribution of seafloor habitats. We present the results of the bathymetric, geologic, and habitat mapping projects, and also discuss technical issues that were key to our success, including: 1) pole vs. towbody transducer placement, 2) acquiring water-column and bathymetry data simultaneously, 3) data processing, and 4) working cooperatively and innovatively with contractors.

 

Habitats and seascapes in Norwegian waters – A bird’s perspective

Terje Thorsnes1, Ole Christensen1, Oddvar Longva1,

Aivo Lepland1, and Jan Helge Fosså2

1) Geological Survey of Norway, Trondheim, Norway

2) Institute of Marine Research, Bergen, Norway

 

Covering an area of c. 3 500 000 km2, the geo-habitats in Norwegian waters range from littoral rocks and sediments, through fjords and the skerryguard, to the shelf, canyons, continental slope and abyssal plains, including oceanic ridges and volcanic islands. A variety of geological processes have shaped and still influence these habitats. The fjords, the skerryguard and the shelf have been severely affected by uplift and repeated glaciations, the shelf margin and uppermost continental slope have been affected by major submarine slides, and the structure of the oceanic ridges and volcanic islands is governed by plate tectonic processes.

 

Active processes today include e.g. deposition, sediment transport, erosion, venting and seeping, submarine slides, iceberg drop stones and glacial action. Habitat studies in Norwegian waters have so far had a regional or local extent, focussing on a limited number of small to medium scale habitats. This study is the first attempt to present a wide angle view of habitats, in order to provide a national framework. Using concepts such as mega-habitats proposed by Greene et al. has been a natural first step in this work, and the work is also inspired by the “continent scale” approach used by Harris and co-workers.

 

Sea floor and Habitat Mapping using AUVs and ROVs

Chris Roper

Roper Resources Ltd

The Gavia AUV is a 2000 meter depth rated modular AUV that can easily be reconfigured to deploy specific science and commercial sensors. The standard sensor suit consists of side scan sonar, still camera, DVL, USBL, CTD and back scatter. The University of BC will take delivery of a Gavia AUV system in early June, 05. The Seaeye Falcon is a 300 meter depth rated ROV system that has recently be used to perform rock fish habitat assessment on the BC coast. The Falcon ROV can be outfitted with a number of sensors, high resolution video cameras, suction and mechanical recovery devices.

 

Using angular response curves for sediment classification

and to extract geoacoustic parameters

Ole Christensen1,Jan Helge Fosså1, Oddvar Longva1 and Terje Thorsnes1

 

1) Geological Survey of Norway, Trondheim, Norway

2) Institute of Marine Research, Bergen, Norway

 

Multibeam bathymetry is widely used in marine science, but multibeam backscatter has been used only to a limited extent. Multibeam backscatter is the incoherent part of the energy return from the sea floor, and is related to e.g. roughness, hardness and the slope of the sea floor. The two first factors are to a large degree controlled by the properties of the substrate. Benthic biota, especially large habitat forming species such as kelp and corals, also affect the backscatter. This may introduce difficulties for geological mapping, but opens new potential for mapping biota. Grab-sampling or video inspection are the most used methods to determine the bottom substrates in areas mapped with multibeam echosounder. However, ground-truthing is not without problems; it takes time, there is a risk of damaging vulnerable habitats and it can be difficult to obtain representative samples. Backscatter intensity measured from various grazing angles provides information on sediment properties and can thus reduce ground-truthing. Plotting backscatter intensity from critical angle against nadir separates the sea floor into three categories. These categories correlate to standard sediment types as fine-grained (clay-silt), medium-grained (sand) and coarser-grained (gravel – till) sediments. Soft till and Lophelia deep-water coral reefs show a distinct acoustic response that can be used to identify and separate these bottom types or biota from the standard sediment classes. Boundaries around areas with similar acoustic response can be drawn manually with unprocessed backscatter data, but boundaries can also be drawn automatically if the so-called grazing angle effect or stripe effect is removed. Supervised coral reef mapping have partly been successful using backscatter data where the grazing angle effect has been removed. Acoustic classification of coral reefs has been performed with single beam echosounder and the backscatter from critical angle.

 

Improvements in habitat mapping by fusion of

bathymetric LIDAR and hyperspectral data

Grady Tuell1 and Bill Gilmour2

1) Optech International Inc., Kiln, MS

2) Fugro Pelagos Inc., San Diego, CA

 

In September 2003, Optech delivered the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system to the Joint Airborne Laser Bathymetry Technical Center of Expertise (JALBTCX). JALBTCX represents a unique partnership between the US Army Corps of Engineers (USACE) and the Naval Meteorology and Oceanographic Command (NAVO). Their mission is to pursue the advancement and exploitation of airborne LIDAR technology.

 

CHARTS is the first airborne lidar designed to facilitate complete mapping of the littoral zone. It consists of a fully-integrated SHOALS bathymetric lidar, topographic lidar, and digital camera; and a new suite of data acquisition and processing software (SHOALS GCS). Optech has brought this technology to the commercial market as SHOALS-1000T. Fugro Pelagos Inc. have purchased such a system.

 

The integration of a passive imaging spectrometer and development of associated algorithms and software for data fusion are being conducted by Optech under the project name Adding Hyperspectral to CHARTS. This upgrade will enable JALBTCX to accomplish rapid environmental assessment (REA) surveys, and may prove to be well-suited to specific environmental mapping applications such as coral reef mapping.

 

In clear shallow waters, airborne laser bathymetry and imaging spectroscopy offer complimentary datasets for use in mapping the sea floor. Together they can be used to characterize both its geometry and constituency. Optech’s strategy for accomplishing REA with the SHOALS technology consists of two approaches: the extraction of new information from SHOALS data; and the adoption of a data fusion approach permitting the estimation of environmental parameters by combining SHOALS data and passive spectral data.

 

In this presentation, we show preliminary results using software developed for these purposes and data collected simultaneously with a SHOALS-1000 bathymeter and casi-2 spectrometer over the South Florida Ocean Testing Center.

 

Characterisation of near-surface ocean bottom sediments from seismic profiling data – forward model and neural-network inversion scheme

Klaus C. Leurer, Brian O’Connell, and Colin Brown

National University of Ireland, Galway, Ireland

 

The transition from seawater column to sediment bed is not as clearly defined as the boundary between two elastic half-spaces. The porous nature of the sediment, its layered structure and seabed roughness and the spatial variations of these require a more sophisticated approach when the characterisation of the seabed with acoustic methods is desired.

 

We have developed a quantitative forward model to calculate velocity and attenuation of compressional waves in a wide range of soft granular marine sediments. It considers the mechanical properties of the sediments’ constituents and allows the generation of normal-incidence synthetic seismograms from multi-layered unconsolidated marine sediments. This model is based on Biot’s poroelastic theory (Biot, 1956) and includes two viscoelastic extensions to the original Biot formulation to enable the resulting extended model to cover a wider range of sediment types. The first extension is introduced to account for the unconsolidated granular nature of marine sediment (Contact model; Leurer and Dvorkin, 2000) and the second to cover the clay-bearing fine-grained part of the range of these sediments (Effective-grain model; Leurer, 1997). With our proposed model, velocity and attenuation of compressional waves in a wide range of soft granular marine sediments can be calculated in terms of the mechanical properties of their constituents.

 

Assuming a spherical grain shape for the sediment particles, a possible parameterization for our forward model to produce the corresponding synthetic seismogram comprises: water temperature, salinity, and hydrostatic pressure; carbonate content, clay content, montmorillonite content; medium grain size; porosity. The unique relationship between the chosen input parameters and the calculated synthetic seismogram represents a valuable tool for studying the acoustic response of pre-specified seabed scenarios.

 

Fig. 1: From left to right: Synthetic seismogram, impedance [kg/(m{fs13 2}s)] vs. two-way traveltime [ms],par compressional-wave velocity [m/s], attenuation, and porosity vs. depth [m].}

The main purpose of the forward model, however, is to provide the basis for an inversion scheme to extract as much information on sediment physical properties as possible from a measured seismogram. After a wavelet transform-based denoising procedure, the measured seismogram is transformed in a way that yields the traveltimes of the detected reflections and the corresponding intrinsic attenuation of the respective overlying sediment layer. These traveltimes and attenuation values, along with a measure of the intensity of the respective reflection patterns, represent the input set for the inversion scheme, which is realized by a neural-network approach. Preliminary trials with synthetic seismograms can recover important sediment parameters (e.g., acoustic velocities, porosities, thicknesses) of a pre-defined layered sediment model.

 

Our neural-network inversion scheme based on our forward geoacoustic model can provide reliable sediment physical properties of the seafloor and the underlying layers. In addition, as our model allows calculation at any frequency of the (frequency-dependent) intrinsic sediment properties, the results of an inversion can serve as a reference for acoustic backscatter data (collected from multibeam or sidescan sonars) which are usually gathered at higher frequencies. Future tasks will include sensitivity analyses to single out those physical sediment parameters that exhibit the greatest influence on the acoustic response.

 

References

 

Biot, M.A., 1956, Theory of propagation of elastic waves in a fluid-saturated porous solid. I. Low-frequency rang. II Higher-frequency range. J. Acoust. Soc. Am., 28, 168-191.

Leurer, K.C., 1997, Attenuation in fine-grained marine sediments: Extension of the Biot-Stoll model by the “effective grain model” (EGM): Geophysics, 62, pp. 1465-1479.

Leurer, K.C., 2004, Compressional- and shear-wave velocities and attenuation in deep-sea sediment during laboratory compaction. J. Acoust. Soc. Am., 116, 2023-2030.

Leurer, K.C., and Dvorkin, J., 2000, Intergranular squirt flow in sand: Grains with viscous cement, Int. J. Solids Structures, 37, pp. 1133-1144.

Leurer, K.C., and Dvorkin, J., Viscoelasticity of precompacted unconsolidated sand with viscous cement. Under Review.

 

Modelling multibeam back scatterings from a rough seabed

Jiashun Yu1, Stuart Henrys1, and Colin Brown2

1) Institute of Geological and Nuclear Sciences, Wellington, New Zealand

2) National University of Ireland, Galway, Ireland

 

We have developed a new algorithm and software to forward model multibeam acoustic swath backscatter from the seafloor. Our code employs a user-provided 2D model of the seabed specifying its roughness and properties across the ocean/sea-floor interface. Tests on a suite of canonical models are used to validate amplitude variation of the synthetic data over a broad range of seafloor reflection coefficients. Numerical tests also show the angular response of roughness and geometry of the seabed on multibeam backscattering strength. The synthetic angular response for different frequency sonars (up to 100 kHz) provides improved discrimination of lithology and is the starting point for inversion and classification of seafloor physical properties.

 

Physical proxies to predict biological assemblages on a tropical shelf:

An example from the northern Great Barrier Reef, Australia

Robin J. Beaman1 and Peter T. Harris2

1) School of Geography and Environmental Studies, University of Tasmania, Hobart

2) Marine and Coastal Environment Group, Geoscience Australia, Canberra

 

 

Due to the difficulty of mapping the distribution of benthic biodiversity on continental shelves, an important question is whether geological and physical data can be used as a proxy to predict the occurrence of assemblages of benthic organisms? In this study, we mapped a low-relief Area A and a high-relief Area B in the northern Great Barrier Reef with a multibeam swath echosounder, Chirp seismic profiler, and conducted extensive water column, seabed and underwater video groundtruthing. This paper reports on the techniques used to discriminate benthic habitats and biological communities in the two areas. Multivariate statistical analysis was used to examine the relationships between environmental variables and biological assemblages. We define the combination of geological and physical factors which are the best proxies for predicting benthic biodiversity on the tropical shelf.

 

Benthic characterization using multibeam bathymetry,

towed video, and spatial statistics

Michael Parke1, John Rooney2, Erin Lundblad2, Joseph Chojnacki2,

Megan Moews2, and Joseph Laughlin2

 

1) Coral Reef Ecosystem Division, NOAA Pacific Islands Fisheries Science Center, Honolulu, HI, USA

2) University of Hawaii Joint Institute of Marine & Atmospheric Research Coral Reef Ecosystem and Coral Reef Ecosystem Division, NOAA Pacific Islands Fisheries Science Center, Honolulu, HI, USA

 

The NOAA Pacific Islands Fisheries Science Center Coral Reef Ecosystem Division (CRED) is engaged in ongoing work with multiple partners to characterize and map the benthos of Pacific Island marine environments to depths of 200+ m. As a corollary to our primary mapping mission, CRED was contracted by the U.S. Navy to provide a detailed benthic characterization of their anchorage areas in Saipan, Commonwealth of the Northern Marianas. Acoustic data from multibeam and backscatter surveys, towed video data, and diver surveys were used to create continuous grids of high-resolution bathymetry, backscatter imagery, and bathymetric position index, and discrete point descriptions of substrate composition and structure, as well as types and quantities of benthic cover, at a variety of resolutions. Continuous benthic cover maps were then produced using a variety of spatial statistical methodologies. This paper will describe the methods used and the problems encountered in producing continuous benthic cover maps based on relatively sparse ground truth data.

 

Combining acoustic and visual surveys for nearshore habitat mapping

Brian D. Bornhold and John R. Harper

Coastal and Ocean Resources Inc., Sidney, BC, Canada

A pilot field program was undertaken in northern Bristol Bay, Alaska to assess the utility of using a combination of acoustic (sidescan sonar) and visual (seabed video) techniques for nearshore habitat mapping and monitoring. Three sites were selected in coastal embayments: western Ungalikthluk Bay, northeastern Summit Island and western Metervik Bay. Sites were surveyed from the intertidal zone to maximum water depths of about 15 m.

 

This pilot project has demonstrated the efficacy of using a combination of sidescan sonar and towed seabed video imagery for habitat delineation in nearshore areas. Sidescan sonar provides complete seafloor acoustic coverage for mapping substrate types. Ground-truth for substrate interpretations and biological data are provided by video imagery collected with the Seabed Imaging and Mapping System (SIMS, a towed video system). High-frequency (390 kHz) sidescan sonar was able to be used to map eelgrass distributions. The study showed that sufficient precision exists to use sidescan, ground-truthed by visual data, for monitoring longer-term changes in the distribution of eelgrass.

 

The combination of geological data with biological data from towed video allowed habitat associations to be delineated. The following associations were identified by combining the dominantsubstrate and floral components: (1) Eelgrass – sandy gravel, (2) Bladed kelps – sandy gravels (with filamentous red algae), (3) Foliose red algae – muddy-sandy gravel and (4) Coralline algae – bouldery/cobbly sandy gravel (with green urchins and bryozoans). The habitat units can be mapped and associated epibenthic communities can be semi-quantitatively defined.

 

The videography classification has also been evaluated for monitoring potential. Assessments of errors associated with video mapping revealed: positional errors of ±4m (95% confidence), no significant intra-classifier error (one mapper classifying replicate images) but some differences of inter-classifier error (two mappers classifying the same imagery); classifier error was resource-dependent (e.g., some species are more easily classified than others). Sensitivity analysis of eelgrass mapping data suggests that the technique is robust enough to detect quite small changes in eelgrass covers; cover changes of less than 10% can be detected under most conditions.

 

Mapping of potential habitats in a deep-water coral reef off Norway: A comparison of visual and computer-assisted methods to interpret sidescan sonar data

V. Hühnerbach1, Ph. Blondel2, V.A.I. Huvenne1&3 and A. Freiwald4

1) Southampton Oceanography Centre, UK

2) Department of Physics, University of Bath, UK

3) Renard Centre of Marine Geology, Gent University, Belgium

4) Institute of Paleontology, University of Erlangen-Nuremberg, Germany

 

During a research cruise in 1999, the Sula Ridge, an almost 14 km long and up to 35 m high deep-water coral reef structure on the Mid-Norwegian shelf mainly built by Lophelia pertusa, was entirely mapped with high-resolution sidescan sonar. In addition, a dense echosounding grid, underwater video observations and dives with the manned research submersible JAGO provided precise high-quality ground-truthing and allowed a detailed interpretation of the reef structure and its surrounding geological features from the sidescan sonar imagery. The result of this visual sidescan sonar interpretation is a facies map that delineates different potential habitats within coral environment, e.g. live coral reef, dead coral structure, sediment covered coral etc.

 

In an attempt to improve this interpretation, computer-assisted image analysis was applied to a representative section of the sonar data, trying to reveal patterns “invisible” to the human eye (using the University of Bath TexAn software). Texture analysis uses Grey Level Co-occurrence Matrices (GLCMs) to calculate statistical indices quantifying the distribution of grey levels and their spatial relationship within the image. For example, regions of rough texture (coral mounds) can be distinguished from areas of smooth background sediment or zones of heterogeneous texture resulting from sediment-covered coral debris and dropstones colonised by sponges.

 

The results of this computer-assisted approach were carefully compared with the earlier visual interpretation to identify the differences and to see where the interpretation could be improved. Overall, it is shown that texture analysis certainly is a useful tool to make facies/habitat mapping from sidescan sonar easier and faster, revealing details overlooked during visual interpretation. However, validation of certain details by an experienced interpreter might still be necessary, and therefore visual and computer-assisted interpretation should be used as complementary tools.

 

Multi-scale terrain analysis of multibeam data from the Irish continental slope

Margaret Wilson, Anthony Grehan, Ivor Marsh, Janine Guinan, and Colin Brown

Department of Earth and Ocean Sciences, National University of Ireland, Galway, Ireland

 

Multibeam bathymetry data acquired under the Irish National Seabed Survey has revealed the geomorphology of the Irish continental margin in unsurpassed detail. This dataset provides a good starting point for the investigation of benthic habitat across the entire region.

 

The continental slope offers particular challenges for extraction of information from Seabed Survey data useful for habitat mapping, including decreased multibeam feature resolution with depth. Through examination of a canonical region on the continental slope to the southwest of Ireland (between 200 and 2000 m water depth) we point out these challenges and describe a synthesis of methods which allow us to move beyond just basic bathymetry map products and characterise seabed terrain at multiple scales in a GIS environment.

 

We are interested in obtaining quantitative descriptors of seabed terrain which are of potential relevance in the prediction of habitat suitability for certain key species or groups of animals across the continental slope. These descriptors, or indices, include slope; ruggedness; roughness; bathymetric position; aspect etc., some of which can be determined using commercial GIS and some which employ other tools. In particular we look at the effect of deriving these indices at multiple scales across the different depths of the continental slope. We demonstrate ways in which we can select an analysis scale relevant to the seabed terrain rather than limiting analysis to an arbitrary scale determined by the data resolution.

 

Each of the terrain indices forms a raster layer which can be used in further analysis in a GIS environment, however each must be considered in relation to ground-truth information which reveals the true benthic habitat. To examine the relevance of each layer we compared values of the various indices with ROV-based video observations which were available in portion of the study area. These geo-referenced video observations allowed the delineation of seabed facies and the registration of presence or absence data for selected faunal groups

 

Finally we discuss the utility of these terrain indices as parameters in habitat suitability modelling which forms part of our on-going research, and how these indices and modelling requirements may also help to shape forthcoming ROV-based fieldwork.

 

Using benthic mapping data to evaluate the coastal/marine

ecological classification standard

 

Rebecca J. Allee and Marti J. McGuire

NOAA Restoration Center, Silver Spring, MD, USA

The Coastal/Marine Ecological Classification Standard (CMECS) is an effort to establish a protocol for a consistently-applied framework for classifying marine and coastal habitats, and it has drawn from existing classification systems throughout the development process. The classification standard is organized as a hierarchy of descriptive units that span a range of scales from the highest level of ecological region (scale: 100 km2 – 1,000 km2) to the lowest level of biotope (scale: 1 m– 100m2).

 

Pilot studies were conducted in an effort to evaluate and review the CMECS standard. In order to identify issues in applying the classification structure and to determine the feasibility of translating existing datasets, the pilot studies incorporated benthic habitat data sources that have been classified with alternate classification systems. The data sources were of varying map scale resolutions and were primarily collected through the use of remote sensing techniques. The use of remote sensing data revealed limitations and restrictions of current mapping technology that ultimately influence the ability to resolve the differences among categories throughout all levels of the classification hierarchy. The primary issues were limitations of depth and image resolution inherent to remote sensing technology as well as the limited ability to remotely capture vertically-stratified and functional parameters. Determining a feasible methodology for applying the classification at the lower levels of macrohabitat, habitat, and biotope to both existing and future mapping efforts will help to provide a meaningful and consistent reference tool for coastal resource managers.

 

The methods and results of the pilot studies are presented along with recommendations for refining the classification standard.

 

Developing a marine landscape classification for UK seas

Neil Golding

Joint Nature Conservation Committee, Peterborough, UK

Arguably one of the key challenges in environmental governance is the development of effective strategies for the protection, management and recovery of marine ecosystems. Such strategies are especially important given the need for rapid and effective action to halt and hopefully reverse the recently assessed downward trends in marine ecosystem quality around the UK (Covey & Laffoley 2002).

 

Often in the past, a prominent tool to develop effective strategies has been an underlying but key emphasis on biological mapping and the development of classification systems for habitats and species. Whilst such direct mapping and classification are valuable exercises in their own right, marine managers have been slow to realise the shortcomings of such approaches. Finite resources and the inherent difficulty of surveying the marine environment, especially in the offshore zone, limit the speed and geographical scope over which such information can be generated.

 

Where offshore marine protected areas are starting to be considered, the challenge is no longer just in the legislative framework, but also in the relative lack of detailed biological information on which to select sites to meet legislative demands and address wider management actions. Such challenges must be overcome if countries are to improve their marine management strategies, and properly implement spatial planning techniques to underpin sustainable use of the marine environment. Recent studies have demonstrated the value of using geophysical data to map broad ecological habitats, in an attempt to develop management strategies in the absence of detailed biological data (Roff & Taylor, 2000; Roff et al., 2003). With the comparatively rapidly generated non-biological classification mechanisms, geophysical approaches are increasingly being seen as a rapid way of achieving a cost effective understanding of the marine resource in the wider environment. This paper will describe how the approach by Roff et al (2003) was successfully adapted and further developed to successfully map UK waters as part of its Review of Marine Nature Conservation.

 

A marine landscape classification was initially developed for the Irish Sea, using broadscale and readily available geological/physical datasets to map a series of marine landscape types for the seabed and water column (Golding et al., 2004; Vincent et al., 2004). For each of these types, it was possible to ascertain (or predict) their characteristic biological communities, allowing them to be used for marine environmental management purposes, particularly in the absence of detailed biological data. The ecological validity of the marine landscapes identified in the Irish Sea was tested using biological data gathered through two dedicated surveys, demonstrating that the marine landscape maps developed for the Irish Sea generally had ecological coherence. The presentation will describe this new approach to mapping in detail, and offer conclusions on its potential benefit for marine environmental management.

 

The value of marine landscapes as a useful basis to aid marine spatial planning has been recognized in the UK, where a consortium of Government departments, Agencies and NGOs are funding an extension of the marine landscape classification to cover the UK Continental Shelf (UKCS). This extension to the UKCS will allow further development and refinement of the classification methodology, and will be discussed further in this paper. The resulting broadscale maps will form part of the UK contribution to a wider European mapping initiative, Mapping European Seabed Habitats (MESH), which is being undertaken by 12 partners from the UK, Ireland, the Netherlands, Belgium and France, with the financial support from the European Union. MESH aims to deliver harmonised maps for NW European seas, and develop standards and protocols to underpin future habitat mapping programmes. Within the MESH programme, partner countries are keen to replicate the success of the marine landscape classification developed in the UK, and plan to work towards producing a equivalent broadscale marine landscape map for the entire NW European sea area.

 

References

 

Covey, R. & Laffoley, D.d’A. 2002. Maritime State of Nature Report for England: getting onto an even keel. Peterborough, English Nature

 

Roff, J.C., & Taylor, M.E. 2000. Viewpoint; National frameworks for marine conservation a hierarchical geophysical approach. Aquatic Conserv: Mar. freshw. Ecosyst. 10: 209-223.

 

Roff, J.C., Taylor, M.E & Laughren, J. 2003. Geophysical approaches to the classification, delineation and monitoring of marine habitats and their communities. Aquatic Conserv: Mar. Freshw. Ecosyst. 13: 77-90.

 

Golding, N., Vincent, M.A., & Connor, D.W. 2004. Irish Sea Pilot – a Marine Landscape Classification for the Irish Sea, JNCC Report 346

 

Vincent, M.A., Atkins, S.M., Lumb, C.M., Golding, N., Lieberknecht, L.M. and Webster, M. 2004. Marine nature conservation and sustainable development – the Irish Sea Pilot. Report to Defra by the Joint Nature Conservation Committee, Peterborough.

 

The first GeoHab publication – “Characterization and mapping of seafloor conditions for the use of habitat delineation based on the latest technologies and methodologies”: Contents and status

 

Brian Todd1 and H. Gary Greene2

1) Geological Survey of Canada (Atlantic), Dartmouth, NS, Canada

2) Center for Habitat Studies, Moss Landing Marine Laboratories, California, USA

 

The first formal publication of the GeoHab organization has been prepared for publication as a Marine Benthic Habitat Mapping Special Publication of the Geological Association of Canada. This special publication consists of seven chapters that describe the technologies and methodologies commonly used today to characterize and map marine benthic habitats. It is a first of its kind publication and should be a useful reference volume as well as helpful in teaching the methodologies of habitat mapping. Chapter 1, “Introduction”, and Chapter 2, “Modern Technologies – Acquisition and Processing”, review methods and equipment used in the collection of seafloor data and describe data processing procedures. Chapter 3, “Mapping Techniques”, and Chapter 4, “Classification Schemes” describe the various techniques presently being applied to habitat mapping and present classification schemes that are being used to characterize potential and actual marine habitats. Chapter 5, “Case Histories”, presents extensive and varied examples of habitat mapping. Chapter 6, “Sea Floor Disturbances”, consists of a few documented studies where mining and other activities have disturbed the seafloor. Finally, the last chapter, Chapter 7, “Marine Policy”, presents papers on how marine benthic habitat mapping is influencing the management of living resources of the world’s oceans. Over 35 individual papers with 85 authors and co-authors from 10 countries have been submitted producing over 700 pages of text and 200 illustrations. Many figures are in color. The volume is expected to be published and available to the public in the Fall of 2005.

 

Volcanic edifices of Southeastern Alaska as promising groundfish habitat

 

Cleo Brylinsky1, H. Gary Greene2 and Tory O’Connell1

 

1) Alaska Fish and Game, Sitka, AK, USA

2) Center for Habitat Studies, Moss Landing Marine Laboratories

Moss Landing, California, USA

 

 

Remotely-sensed acoustic data collected at Fairweather Ground and the offshore Edgecumbe lava field in SE Alaska detail several eroded volcanic cones that may constitute important habitat for groundfishes. Based on multibeam and backscatter data collected with high-resolution Reson SeaBat 8111 100 kHz and 8101 240 kHz systems and side-scan sonar data collected with a 150 kHz Acoustic Marine System (AMS-150), geological aspects of these volcanic cones can be inferred. These features have high, sharp relief, are tens of km across, and are of complex morphology, with differentially eroded beds of alternating lava flows and ash layers, as depicted for Fairweather Ground (above). In situ observations made from manned submersible dives indicate that these features provide habitat for dense concentrations of commercially targeted yelloweye rockfish (Sebastes ruberrimus) and lingcod (Ophiodon elongates). Although further study is needed, these geomorphic features may be appropriate for consideration as Marine Protected Areas (MPAs).

 

Habitat mapping of Hexactinosidan sponge reefs

using video and multibeam bathymetry

 

S.E. Cook1, K.W. Conway2, J.V. Barrie2 and M. Krautter3

 

1) Department of Biology, University of Victoria, Canada

2) Geological Survey of Canada, Pacific Geoscience Centre, Canada

3) Institute of Geology and Paleontology, University of Stuttgart, Germany

 

Video transects mapped onto multibeam swath bathymetry data of hexactinosidan sponge reefs on the Western Canadian continental shelf show clear associations of rockfish, seas stars, Rosselid sponges and crustaceans with the live sponge reef habitat. The video was taken using the manned submersible Delta in June 1999 aboard CCGS John P. Tully and was analyzed by extracting ‘snapshots’ (equivalent to a quadrat) along the video transects at 10 second intervals. Habitat type (live reef, dead reef or off-reef), a qualitative measure of complexity (low, medium or high) and any organisms in each snapshot were identified to the lowest taxonomic level and enumerated. The multibeam survey of the Hecate Strait sponge reef complex was accomplished in July and August 2003 aboard CCGS Vector. The data were then processed using CARIS software and exported into ArcInfo software for image processing. The video transect data were also imported into ArcInfo from a Microsoft Excel database. Any snapshots that did not have GPS data associated with them were interpolated using simple trigonometry and the assumption that the submersible traveled at a constant speed between the GPS fixes. This method of habitat mapping will help to further our understanding of the ecological role that the globally unique sponge reefs play in the continental shelf ecosystem.

 

Importance of capelin (Mallotus villosus) biology in sustaining trophic

interactions in the Northwest Atlantic

 

G.K. Davoren1, C. May1, P. Penton1, N. Record2, B. deYoung2 C. Burke3,

W.A. Montevecchi3, D. Andrews3, A. Buren3&5, C. Rose-Taylor4&5,

T. Bell4, M. Koen-Alonso5, J.T. Anderson5

 

1) Department of Zoology, University of Manitoba, Winnipeg, MB

2) Department of Physics, Memorial University of Newfoundland, St. John’s, NL

3) Cognitive & Behavioural Ecology Programme, Departments of Biology & Psychology, Memorial University of Newfoundland, St. John’s, NL

4) Department of Geography, Memorial University of Newfoundland, St. John’s, NL

5) Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John’s, NL

 

Capelin (Mallotus villosus) is the focal forage fish species in the Northwest Atlantic, preying on invertebrates and being preyed on by most large vertebrate predators. Recently, the biology and behaviour of capelin has changed dramatically. The basis for these changes is not well understood and has led to considerable uncertainty in capelin stock status. Through a collaborative, interdisciplinary initiative we investigate the bio-physical mechanisms underlying these changes. Owing to globally and regionally significant populations of marine fish, birds and mammals, we focus on the area encompassing Funk Island on the northeast coast of Newfoundland. Combining ROV observations with sediment grab and seabed mapping systems, we investigate the relative contribution of beach versus off-beach (demersal) spawning to overall reproductive success. A number of persistent demersal spawning sites (18-30 m) have been found that have similar developmental/survival rates to nearby beach sites. Integrating biological sampling with hydroacoustics both during a meso-scale survey (~1600 km) and at stationary mooring sites, we examine the vertical distributional/migratory patterns of capelin in relation to the thermohaline properties of the water column, combined with the density and distributional patterns of capelin predators and prey. This revealed that capelin and their invertebrate prey consistently conduct diel vertical migrations. Finally, by integrating seabird diets (Funk Island) with capelin and other prey abundance data obtained during the survey, we plan to model how the use of food resources by these predators changes with capelin availability during the breeding season, and explore its implications for predator energetics and dynamics. We anticipate that this research will further increase our understanding of the recent changes in capelin biology and their implications for other trophic levels.

 

Incorporating interpreted geological survey data and rockfish observations into stock assessments

C. Grandin1, K. Picard2, K. Conway2, L. Yamanaka1, L. Lacko1, J. Martin1

1) Department of Fisheries and Oceans, Science Branch, Pacific Region,

Pacific Biological Station, Nanaimo, B.C. V9R 5K6, Canada

2) Geological Survey of Canada, Pacific Region, Sidney Pacific Geoscience Centre, Sidney, B.C. V8L 4B2, Canada

 

A submersible survey was conducted in September 2003 to collect observations of quillback and yelloweye rockfish and their associated habitats. The survey was stratified by surficial geology type, interpreted from geophysical survey data. Bathymetric and backscatter data from multibeam sonar and additional information from high resolution seismic profiling (Huntec DTS) and sidescan sonar was used to interpret surficial geology. During the submersible dives, for all fish observed, species, total length, and perpendicular distance from centerline were recorded. Although dives were conducted over mud, sand, glacial sediments and bedrock habitats, Quillback and yelloweye rockfish were only observed over bedrock/scarp habitats. A correspondence analysis of all species observed against surficial geology demonstrates this observation. Analysis of the observational data includes the creation of Probability of Detection Functions (PDFs) to estimate planar rockfish density (Buckland et al, 1993); this estimate of rockfish density by surficial geology type was expanded to a biomass using the total area of surficial geology type in the region. Biomass estimates based on visual observations and habitat maps are a key component of inshore rockfish stock assessments. Because of the close association of rockfish with bedrock/scarp habitats, surficial geology maps will enable strategic site and boundary selection of RCAs.

 

Preliminary results obtained using a ROV mounted RESON SEABAT 7125 multibeam during recent deep-water habitat mapping surveys

 

A.J. Grehan1, M. Wilson1, D. Toal2, C. Brown1, J. Riordan2,

J. Guinan1, R. Hill3 and P. Connolly4

 

1) Ocean Mapping Group, Department of Earth and Ocean Sciences, National University of Ireland, Galway, Ireland

2) Department of Electronic and Computer Engineering, University of Limerick, Ireland

3) Reson Offshore Ltd., Aberdeen, UK

4) Marine Fisheries Services Division, Marine Institute, Galway, Ireland

 

The use of Remotely Operated Vehicle (ROV) mounted multi-beam, for the generation of high resolution bathymetry maps in the deep-sea, is in its infancy. The Department of Electronic and Computer Engineering (University of Limerick), in collaboration with the Ocean Mapping Group, of the Department of Earth and Ocean Sciences (NUI, Galway), recently took delivery of a RESON SEABAT 7125 multi-beam, as part of a project funded by the Irish Higher Education Authority’s ‘Programme for Research in Third Level Institutes’ (PRTLI) Cycle III.

 

The SEABAT is to be used with a variety of ROV’s in the future. Here we discuss the technical logistics involved in mounting the SEABAT on the ROV, data acquisition set-up using RESON PDS 2000 software and the performance of the system following its first deployment during recent deep-water surveys with an inspection class ROV.

 

The use of genetic tagging to assess abundance and distribution of inshore rockfish (Sebastes spp.) within a small marine conservation area in the Strait of Georgia, British Columbia

 

Merran Hague1, Sean Cox1, Lynne Yamanaka2, Lisa Lacko2,

Kristi Miller2, Janine Supernault2, and Kim Picard3

 

1) Fisheries Science and Management Research Group, School of Resource and Environmental Management, Simon Fraser University, Burnaby, B.C.

2) Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, B.C.

3) Pacific Geoscience Centre, Natural Resources Canada, Sidney, B.C.

Email: mjhague@sfu.ca

 

Fisheries and Oceans Canada (DFO) has recently implemented a spatial management strategy to address conservation and management concerns regarding British Columbia’s inshore rockfish stocks. To date, eighty-nine rockfish conservation areas (RCAs) have been closed to rockfish and lingcod harvest. Unfortunately, the unique habitat requirements and physiological characteristics of inshore rockfish inhibit the effectiveness of stock monitoring methods. In our study, we evaluated the use of a novel, in situ genetic tagging technique to evaluate the abundance, distribution and movement of copper and quillback rockfish, Sebastes caurinus and S. maliger, within a small RCA in the Strait of Georgia. Over 950 rockfish tissue samples were collected during the summer and fall of 2003 and 2004. Site specific abundance estimates were calculated from a subset of 2004 samples that contained sufficient tissue for individual identification. Of the 366 samples analysed, we recorded 12 recaptures (3.3% recapture rate). As inshore rockfish exhibit strong bathymetric associations, we then extrapolated our site estimates throughout the reserve using bottom habitat information collected from a multibeam echosounder transect. Future research will address the impact of uncertainty in recapture identity, and will compare the capture recapture estimates to estimates obtained using the swept area method. Our preliminary results identify genetic tagging as a potential alternative to traditional mark recapture experiments for evaluating rockfish abundance, movement and distribution. The combined use of genetic tagging and bottom habitat mapping may be useful for the assessment and monitoring of additional rockfish conservation areas along the B.C. coast.

 

Benthic habitat mapping in Glacier Bay, Southeast Alaska

Jodi Harney1, Guy Cochrane1, Pete Darnell1, and Lisa Etherington2

1) USGS-Pacific Science Center, 400 Natural Bridges Dr., Santa Cruz, CA

2) USGS-Alaska Science Center, Gustavus, AK

 

Geologic substrates of the sea floor in southeast Alaska provide benthic habitats for recreationally and commercially important species, including King, Dungeness, and Tanner crabs, halibut, rockfish, and shrimp. In Glacier Bay, where historical rates of glacier retreat are among the highest documented worldwide, the potential for rapid change in seafloor properties is high owing to paraglacial sedimentation. We use geophysical data, underwater video, and sedimentological tools to understand the distribution, character, and rate of change of geologic substrates and benthic communities in this dynamic environment.

 

In April 2004, more than 40 hours of georeferenced submarine digital video were collected in water depths of 15-370 m in Glacier Bay to: (1) ground-truth geophysical data collected in the central and lower bay (multibeam bathymetry and acoustic reflectance; Carlson et al. 2002, 2003; Cochrane et al. 1998, 2000); (2) examine and record geologic characteristics of the seafloor; (3) investigate the relationships between substrate types and benthic communities; and (4) develop a map of habitat distribution in Glacier Bay.

 

During video collection, real-time observations of seafloor characteristics (including primary and secondary substrate type, slope, rugosity, and benthic biomass) were digitally recorded at 30-second intervals, as were the presence of benthic organisms and demersal fish. Common substrates observed include unsorted glacial till, rippled sands and large sand waves, bioturbated mud, and extensive beds of living scallops and Modiolus (horse mussels). Seafloor observations, sediment grain size, and geophysical data were co-registered, integrated, and analyzed using ArcGIS, ArcGrid, and ERDAS Imagine software* (after Dartnell and Gardner 2004; Cochrane and Lafferty 2002) to formulate predictions of benthic habitat distribution in the central and lower bay from geophysical data alone. In collaboration with scientists from the Alaska Science Center, observations of benthic fauna are being used to investigate the relationships between geological features of the seafloor and the biological communities that inhabit them.

 

References

Carlson, P.R., P. Hooge, G. Cochrane, A. Stevenson, P. Dartnell, and K. Lee. 2002. Multibeam bathymetry and selected perspective views of main part of Glacier Bay, Alaska. USGS Open-File Report 02-391. http://geopubs.wr.usgs.gov/open-file/of02-391

Carlson, P.R., P.N. Hooge, G.R. Cochrane, A.J. Stevenson, P. Dartnell, and J.C. Stone. 2003. Multibeam bathymetry and selected perspective views of Glacier Bay, Alaska. U.S. Geological Survey Water Resources Investigation Report 03-4141 (2 map sheets)

Cochrane, G.R., P.R. Carlson, M.E. Boyle, G.L. Gabel, and P.N. Hooge. 2000. Physical characteristics of Dungeness crab and halibut habitats in Whidbey Passage, Alaska. U.S. Geological Survey Open-File Report 00-032. http://geopubs.wr.usgs.gov/open-file/of00-032/

Cochrane, G.R., P.R. Carlson, J.F. Denny, M.E. Boyle, S.J. Taggart, and P.N. Hooge. 1998. Physical characteristics of Dungeness crab and halibut habitats in Glacier Bay, Alaska. U.S. Geological Survey Open-File Report 98-791. http://geopubs.wr.usgs.gov/open-file/of98-791

Cochrane, G. R., and K.D. Lafferty. 2002. Use of acoustic classification of sidescan sonar data for mapping benthic habitat in the Northern Channel Islands, California. Continental Shelf Research 22: 683-690.

Dartnell, P., and J.V. Gardner. 2004. Predicting seafloor facies from multibeam bathymetry and backscatter data. Photogrammetric Engineering and Remote Sensing. 70 (9):1081-1091.

 

The use and consistency of grey level co-occurrence matrices for the classification of sidescan sonar data from repeated surveys over deep-water coral habitats

 

V.A.I. Huvenne1,2, P. Blondel3, V. Hühnerbach2

 

1) Renard Centre of Marine Geology, Ghent University, Belgium

2) Challenger Division for Seafloor Processes, Southampton Oceanography Centre, UK

3) Department of Physics, University of Bath, UK

 

Deep-water corals such as the species Lophelia pertusa or Madrepora oculata are found at several locations along the ocean margins. In many occasions they built structures or reefs on the seafloor, ranging from a few meters to hundreds of meters or even kilometers in length, and up to several tens of meters in height. Recent studies have shown that these structures are very vulnerable with regard to bottom trawling activities, and an increasing number of reefs are now recognised on the seabed, and become protected.

 

Such developments result in an increase in mapping and monitoring efforts on the deep-water coral reefs, in order to support the management decisions and follow up the situation on the seabed after the decisions have been put in place. Acoustic techniques such as multibeam and sidescan sonar are ideal to investigate these deep habitats, although ground-truthing (through video surveying or sampling) is always necessary. As more and more surveys are carried out and more and more data is generated, the use of computer-assisted techniques to analyse the data becomes more commonplace. Grey Level Co-occurrence Matrices (GLCMs), as an algorithm to quantify local image texture, have proved to be a useful tool for the classification of sidescan sonar images, and to assist in the image interpretation.

 

This contribution presents the results of a comparison exercise. Sidescan sonar imagery was collected repeatedly over several deep-water coral habitats, using different sidescan equipment or different settings on the same system. All data was processed with the same software (PRISM, developed at the SOC) and was subsequently classified using the University of Bath TexAn software, which implements the GLCM algorithms. The first results show that the classification maps of different surveys over a particular area are comparable. The textural indices calculated for the different potential habitat types (such as coral framework, coral rubble, background sediment etc.) are consistent relative to each other and confirm theoretical considerations, i.e. coral framework has a rougher image texture than background sediment, for example. The absolute values, however, may differ between the surveys. Apart from the typical classification difficulties encountered with sidescan sonar imagery, such as the presence of shadows and nadir lines, which cause strong contrasts and particular image textures, each system or system setup also has its own particularities (e.g. calibration). Different sidescan sonar records may already have a different appearance to the naked eye, and in some cases the algorithms exploit and enlarge these differences. However, these differences themselves can also reveal extra information, and in this way increase the value of the surveys.

 

Overall, GLCM’s are a useful sidescan imagery classification aid, because they quantify the image textures and point to features easily overlooked by the naked eye. However, the input from experts is still needed for the interpretation. Furthermore, it may be clear that in regular monitoring surveys the best results will be obtained when using the same equipment and setup for every survey. However, the comparison of repeated surveys with slightly different systems also has its value.

 

Managing systematic residual errors in multibeam backscatter data

Kashka Iwanowska1, John E. Hughes Clarke2, Kim W. Conway1 and Vaughn Barrie1

1) Geological Survey of Canada-Pacific, Sidney, BC, Canada

2) Ocean Mapping Group, University of New Brunswick, Fredericton, NB, Canada

 

In support of the Geoscience for Ocean Management Program of the Geological Survey of Canada in the Queen Charlotte and Georgia Basins, over 400 ship-days of EM1002 multibeam sonar data have been collected through five field seasons. One requirement of these mapping activities is to have the ability to discriminate variations in seabed physical properties through the measurement of seabed backscatter strength estimates. While the information content of the initially processed backscatter data is remarkable, a number of systematic residual errors significantly compromise its usefulness for quantitative analysis.

 

The backscatter data would ideally be properly reduced for all geometric and radiometric corrections. Unfortunately, there were a series of systematic hardware malfunctions that introduced a time-varying artefact in the data that was not corrected in the field. As a result, the data are compromised with a slowly varying signature that overprints the true seabed image, hampering quantitative analysis.

 

The principal problem was beam pattern residuals resulting from a combination of transmit and receive radiation sensitivities. The EM1002 uses roll stabilised receiver beams in three vertically referenced sectors. In contrast, the transmit beam patterns are fixed in the sonar reference frame. Thus the resulting artefacts are a mixture of vertically and sonar-referenced signatures. Overprinted on this is the seabed grazing angle variability (of interest for sediment classification), which is referenced to the local seabed slope and refracted ray path. As a result, standard combined grazing angle and beam pattern removal functions are inadequate. A new approach is described herein that tries to model and remove these effects. A secondary effect seen was imperfectly measured pulselength-related source level changes. These offsets changed as the sonar hardware and software were altered over the five year survey period, requiring local, empirical estimates of these offsets.

 

An additional problem with a subset of the data is that the full trace backscatter data were not collected. A reduced version of the data are still available in a beam-averaged form. These data, however, have a significant loss in spatial resolution and are not amenable to textural classification approaches. Methods are described herein that show how the beam-averaged data are used as a substitute. The loss of spatial resolution is shown. With the 200% overlap approach used during multibeam data acquisition, the highest resolution full trace data is actually lost in standard mosaicing. Azimuth specific images are generated that illustrate how this extra resolution can be viewed and used for enhanced interpretation.

 

Once beam pattern residuals are minimised, the remaining shiptrack-linked feature in the mosaics is the fact that the shape of the angular response curves vary as a function of lithology. While this is a real observation, it is disconcerting to the typical interpreter. A method that extracts the local shape of the angular response to facilitate normalization to an equivalent angle-invariant measurement is thus described. The same local normalization function can be used as a classifier. Examples of these are presented.

Integration of oceanographic information from the Heceta Bank

Region off Oregon into fisheries management

Maria Jose Juan Jorda and John A. Barth

College of Oceanic and Atmospheric Science, Oregon State University, OR, USA

 

The goal of this study is to assemble and merge oceanographic data sets from the Oregon and Washington coasts with benthic habitat data with the aim to integrate them in fisheries stock assessment models, as well as to serve as information for any fisheries management and conservation issues. The main study area is Heceta Bank (44N) off Oregon which is a region of high productivity and is an important fishing ground for a number of commercially important stocks. In addition, direct observational techniques using submersibles and high-resolution multibeam seafloor mapping projects have been used to characterize benthic habitat over Heceta Bank. There are several fisheries that might benefit from this study, among them the groundfish and hake fisheries.

 

The oceanographic data are comprised of temperature, salinity, chlorophyll concentration, and ocean current velocity. The data are from a variety of sources, including from satellite sensors and in situ measurements from conductivity-temperature-depth instruments and acoustic Doppler current profilers. Sea surface temperature and chlorophyll satellite data ranges from 1997 to 2003. Subsurface temperature, salinity, chlorophyll and velocity data were obtained from the National Oceanographic Data Center and from recent (1997-2003) Oregon State University cruises. Monthly means and standard deviations for each of the oceanographic variables have been computed at various depths from the earliest time available (depending on the variable and time of the year) to 2003 off the Oregon and Washington coasts. The programming language Matlab and a Unix-based gridding program were used to make all the computations and the initial graphics. The gridded oceanographic data are being organized in a GIS system, so data may be combined with bathymetry and benthic habitat information. The GIS will facilitate integration of different layers of information and make them accessible to scientists, fisheries managers, policy makers etc. Work is in progress to explore how oceanographic data may be incorporated into fisheries stock assessment models.

 

Characterizing bedform habitat based on high-resolution multibeam bathymetry, backscatter and video imagery in the San Juan Islands, Washington, USA, and Boundary Pass Region, British Columbia

Holly L. Lopez and H. Gary Greene

Moss Landing Marine Laboratories, CA, USA

 

The San Juan Islands and Boundary Pass regions have a complex tectonic history and have experienced convergence, thrust faulting and uplift, subsidence, glaciation, tidal scour and sediment transport. These processes have changed and shaped both the terrestrial and the marine environment. Metamorphic, plutonic and sedimentary rocks in the San Juan Islands region have been affected by these tectonic processes and have produced diverse marine benthic habitats. These vary from dynamic bedforms, to glacially-scoured moraines, to fractured and faulted bedrock outcrops. Bedforms of differing sizes in the San Juan Islands, including Haro Strait, San Juan Channel, the Strait of Juan de Fuca, and the Boundary Pass region, British Columbia, have been identified based on multibeam bathymetric, backscatter and other geophysical data sets. Bedforms are features of relief created on the bed of a fluid flow as a result of an unstable interaction between the flow and the bed material. The bed may be composed of loose grains, cohesive mud or rock. In the marine environment, variables which influence the creation of bedforms include current velocity, water viscosity, water depth, seafloor slope, sediment concentration, and sediment grain size. These factors influence the size and shape of bedforms which range in size from small ripples to large dune fields. It is possible that currents in the San Juan Islands contribute to bedform construction and are evidence that sediments are being actively transported. Coarse-grained bedforms were identified using an ROV in San Juan Channel where sand lance (Ammodytes spp.) were observed emerging from the sediment waves. Sand lance are commonly found over sandy substrates where sand is used as a place of refuge. There have been numerous studies regarding the relationship between fish and highly rugose substrate; however, the potential relationship between fish and bedforms as habitat, specifically, in the Pacific Northwest, is not known.

 

The goals of this study are: 1) to identify and characterize bedforms which occur in the San Juan Islands and Boundary Pass region; 2) to map their distribution based on remote sensing data according to the deep-water classification scheme for marine benthic habitats used at the Center for Habitat Studies at Moss Landing Marine Laboratories; and, 3) to gain a better understanding of the physical and biological characteristics of the San Juan Islands Archipelago near established Marine Protected Areas (MPAs) in order to most effectively implement resource management objectives. This study is distinctive in that it addresses an unknown potential relationship between fishes and bedforms as habitat within the San Juan Archipelago.

 

The geology and geophysics of habitat mapping on the continental

slope NW of the UK

D.G. Masson and B.J. Bett

Southampton Oceanography Centre, UK

Between 1996 and 2002, a multidisciplinary group of researchers from the Southampton Oceanography Centre undertook an environmental survey of large areas of the continental slope northwest of the UK, in water depths of 200 to 2400 m. The area is a frontier hydrocarbon province, with exploration now extending to water depths in excess of 1500 m. The surveys included seabed mapping using 30 kHz sidescan sonar and 12 kHz multibeam systems, high resolution 3.5 kHz seismic profiling, an extensive sampling programme, and seabed photography. Samples were collected for biological, chemical and sedimentological analysis. The integrated nature of the survey, in which the sidescan data were used as an aid to planning the sampling programme and the samples and seabed photographs were in turn used to help ‘groundtruth’ the sidescan data, was an important element of the overall survey package.

 

The northwest UK margin is an excellent area to explore how seabed sediment facies contributes to the variability of the biological communities that inhabit the seafloor, and how an understanding of seafloor sediment facies distributions might be used in understanding seafloor habitats. The seabed sediment facies on the northwest UK margin are highly variable, ranging from mud to boulders, with gravel seafloor found in some areas to depths of 1200 m or more. Strong bottom currents, driven by water exchange between the Norwegian Sea and the North Atlantic, contribute to the variability of sediment transport and deposition processes at all depths. Sediment bedforms, mapped using sidescan sonar and seabed photographs, give a detailed picture of peak bottom current velocity variation. All of this information can be used to define distinctive ‘habitats’ that can be mapped directly from sidescan sonar images. A strong correlation is found between these geologically defined habitats and the benthic communities that inhabit them. Examples of such habitats include iceberg ploughmarks, sand sheets deposited by bottom currents, and areas of deep-water gravel. We conclude that understanding the geology of the seafloor should be a prerequisite for all habitat studies and that seafloor facies is one of the key factors (along with water depth and water mass character) that influence the variability of benthic communities. This approach is informing the UK’s implementation of the EC’s Habitats Directive and Strategic Environmental Assessment Directive in offshore areas.

 

Acknowledgment: This work was funded by the Atlantic Frontier Environmental Network (AFEN), the UK Department of Industry (DTI) and Southampton Oceanography Centre.

 

Towards a statistically valid method of textural

seafloor characterization of benthic habitats

 

Alan R. Orpin and Vladimir E. Kostylev

 

Geological Survey of Canada (Atlantic), Dartmouth, NS, Canada

 

Multibeam bathymetric sonar technology and benthic habitat research require the systematic characterization and mapping of the seafloor, necessitating reliable and accurate sea floor descriptors in combination with a robust means to statistically assess descriptor associations. Historically, geoscientific sea floor mapping involves identifying the spatial extent and relationship of geological units, broadly following litho– or chronostratigraphic criteria, but these conventions may not be meaningful biologically because they incorporate temporal elements that stem from a geochronological qualifier. Textural properties of geological facies are typically given in terms of distribution-dependent statistics, which have been shown to be inappropriate with multimodal marine sediments, such as on glaciated shelves. As habitat classification is aimed at boundary definition, the boundaries between groups in such cases could be arbitrary, or based on very subtle differences, or noise (e.g. sampling bias). This study uses an independent statistical approach pioneered by Calinski & Harabasz ©-H) which offers significant advantages in determining the appropriate number of groups that might exist in any sample population. Used in conjunction with a multivariate extension to information-entropy, grain size populations can be clustered into statistically validated groups. This study utilizes a 30-year legacy of 4-class grain size data collected from the Scotian Shelf, Canadian Atlantic continental margin, we show that a traditional stratigraphic approach does not provide clear discrimination between basic textural types, and hence, basic benthic habitats. Considerable improvements in textural zonation are obtained using a combination of information entropy-clustering and C-H technique. Two high resolution 32-class particle size data sets yield a solution where no obvious textural groups exist, contrary to published field-based studies. Comparison of sediment grab samples to bottom photographs show that photos capture (sample) the coarsest-gravel component that is sometimes absent from grabs, and therefore, classification from photos creates more groups. This study emphasizes that data resolution and sea-floor sampling strategies should be intimately linked, and to fully unravel high-resolution laser-derived textural data might require a 3-4 order of magnitude increase in the number of bottom sediment samples.

 

Sediment distributions along the continental shelves of the west coast, United States

 

Jane A. Reid1, Nadine Golden1, and Mark Zimmermann2

 

 1) USGS Pacific Science Center, Santa Cruz, CA, USA

2) NMFS Alaska Science Center, Seattle, WA, USA

 

While the importance of substrate type, i.e., rocky or sediment-covered, in benthic habitat analysis is becoming clear, the effect of sediment distributions – gravels, sands, muds – on habitat has not yet been a focus. As a start to the study of sediment texture influence on epifauna, infauna, and other benthic biota, we are compiling existing information for the United States Exclusive Economic Zone (USEEZ) from analyses and descriptions of cores, grabs, dredges, photos, and videos. These data, including sediment texture, composition, color, epi/infauna, as well as locations of rocks and hard-bottom, are standardized, extrapolated, and mined. These relationally linked data are called usSEABED, a USGS-funded national database of seabed characteristics.

 

From these data, we present several broad views (GIS, gridded and draped over bathymetry) of sediment textures over the continental shelves of the west coast of the United States (Washington, Oregon, California), showing the extent of mud belts along the central coast of California and south of the Columbia River, the sandy or gravelly areas near river drainages and estuaries such as the Golden Gate, as well as areas that lack such data. Ongoing work will densify the database, refine the sediment models, reconcile areas of rock and/or sediment in areas of particular interest, and analyze the implications of the sediment distributions on geological processes and benthic biota.

 

Structure-forming benthic invertebrates:

Habitat associations on Oregon’s continental margin

 

Natalie A. Strom1, Chris Goldfinger1, Brian N. Tissot2, and W. Waldo Wakefield3

 

1) Oregon State University, College of Oceanic and Atmospheric Sciences, OR, USA

2) Washington State University Vancouver, Program in Environmental Science, WA, USA

3) NOAA Fisheries, Northwest Fisheries Science Center, Seattle, WA, USA

 

Structure-forming invertebrates belong to a functional group of sessile and sedentary organisms that can significantly enhance the complexity of physical habitats. A number of these organisms, including cold-water corals and sponges, are known to be slow growing and are probably vulnerable to physical disturbance. The degree to which these organisms provide resting and hiding places for fishes, such as those belonging to the genus Sebastes, is a topic of ongoing debate. In addition, as filter feeders, these invertebrates can indicate areas of consistently favorable conditions for feeding and growth. Recent efforts to inventory structure-forming benthic invertebrates have been completed in many areas, particularly in northern latitudes, but few studies of this type have been completed off the Pacific Northwest coast. Geological studies on the Oregon margin using the occupied submersible Delta during 1992-95 sampled an expansive area along the continental shelf and slope, primarily on and around rocky banks offshore of Oregon. The videos from these surveys are being analyzed to inventory and catalog sessile structure-forming invertebrates and to document their associations with geological habitat types at multiple scales. Detailed data on geological substrate, invertebrate diversity, abundance, and density are being compiled and analyzed in relation to a comprehensive geological map of Oregon. It is hypothesized that geological substrate may be used as a predictor of structure-forming invertebrate types and densities in regions not targeted by the surveys.

 

The ‘MESH’ Project: Mapping European Seabed Habitats

 

Gez Thulbourn1 & the MESH consortium of partners2

 

1) Joint Nature Conservation Committee (JNCC), UK

2) University of Gent (UGENT), Belgium

2) Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), France.

2) Marine Institute (MI), Ireland

2) Alterra-Texel, Netherlands

2) TNO Environment, Energy and Process Innovation, Netherlands

2) The Centre for Environment, Fisheries and Aquaculture Science (CEFAS), UK

2) Department of Agriculture and Rural Development / Queen’s University Belfast (DARD/QUB), UK

2) English Nature (EN), UK

2) Envision Mapping Ltd, UK

2) National Museums and Galleries of Wales (NMGW), UK

2) British Geological Survey (BGS), UK

 

MESH is a three year international marine habitat mapping programme entitled ‘Development of a framework for Mapping European Seabed Habitats’ which began in spring 2004. It is being undertaken by a consortium of twelve partners across the UK, Ireland, the Netherlands, Belgium and France with financial support from the EU INTERREG IIIB fund. The project has six scientific work-packages:

1. Generating habitat maps for north-west Europe

2. Developing standards and protocols for marine habitat mapping

3. Testing these protocols

4. Predictive modelling

5. Demonstrating applications of habitat maps for spatial planning and environmental management

6. Communicating the results

 

MESH aims to produce seabed habitat maps for north-west Europe and develop a harmonised approach to surveying, interpretation and presentation of material so that future studies will be compatible and can contribute to a common resource. The end products will include a meta database of mapping studies, a web-delivered geographic information system showing the habitat maps, guidance for marine habitat mapping (including standards and protocols), a series of case-history studies illustrating the use of habitat maps in marine planning and management, and a stakeholder database. The project will culminate in an international conference with published proceedings.

 

New marine map series from the eastern Canadian continental shelf

 

Brian J. Todd, Vladimir E. Kostylev and John Shaw

 

Geological Survey of Canada (Atlantic), Dartmouth, NS, Canada

 

Marine environments need to be managed to obtain a balance between the preservation of natural resources and ecosystems, and appropriate use of those resources to meet the needs of human society. Detailed sea floor maps are required to enable local, regional and federal resource managers to make informed judgements about the effect of different activities on marine habitat. To address this gap in knowledge, the Geological Survey of Canada has undertaken a national sea floor mapping program to cover selected offshore areas of the Canadian continental shelf. The outcome of the program is the development of marine cartographic standards and publication of marine map series for distribution via the World Wide Web. A map series consists of four sheets: topography, backscatter strength, surficial geology and benthic habitat. Topography and backscatter strength maps are derived from data collected using multibeam sonar systems. Geophysical, geological and biological groundtruth surveys provide the necessary field verification to create interpretive surficial geology and benthic habitat maps. All data sets are geospatially assembled through the use of Geographic Information System (GIS) techniques. The GIS approach has become the standard mapping procedure for the integration of multidisciplinary data and identification of representative habitats, and their associated benthic species.

 

On the Scotian Shelf on the eastern Canadian continental margin, the Browns Bank map series is complete and the German Bank map series is nearing completion. Mapping was undertaken on both of these banks because they support lucrative shellfish and groundfish fisheries, yet the benthic habitats on the banks were poorly understood. The decision by resource managers to open new fisheries areas on these banks required new, high-resolution sea floor maps. The Browns Bank map series covers 3056 km2 and comprises four sheets at a scale of 1:100 000. German Bank, with a mapped area of 5320 km2, is divided into three 1:50 000 scale maps, each with four sheets for a total of twelve sheets. Included on the map sheets are descriptive notes, topographic cross sections, interpreted geological cross sections and sea floor photographs representing typical habitat and benthic communities. This mapping approach is being applied to other areas of the Canadian continental shelf to facilitate sea floor management.

 

Application of multibeam bathymetry and surficial geology to the spatial management of scallops (Placopecten magellanicus) in southwest Nova Scotia

 

Brian J. Todd1, Stephen J. Smith2, Gerard Costello2,

Vladimir E. Kostylev1 and Mark J. Lundy2

 

1) Geological Survey of Canada (Atlantic)

2) Fisheries and Oceans Canada

 

The management of scallop fisheries of the Scotian Shelf, Bay of Fundy and the Canadian side of Georges Bank currently includes spatial components. Areas have been identified for seasonal closures to avoid fishing gear conflicts, for different size/meat weight or harvesting restrictions due to spatial variation in scallop growth rates, and for closures to protect recently settled abundant year-classes. However, the development of reference points for harvest levels have generally taken a dynamic pool approach to their definition, ignoring spatial patterns in abundance, age distribution, growth rates and settlement patterns. Recent work has identified large differences in growth rates within relatively short distances for scallop beds in the Bay of Fundy. Ignoring spatial heterogeneity of scallop populations ignores the fact that fishing also concentrates on spatial patterns reflecting growth rates and densities.

 

Canada is committed to developing fine-scale maps of the bathymetry and surficial geology of its continental shelf areas to provide the basis for the management and conservation of the biological and mineral resources within its national jurisdiction. Bottom habitat maps developed from multibeam bathymetry, backscatter strength and geological and biological sampling have been used by the offshore scallop industry to allocate fishing effort. The main benefits of these maps to the fishing industry have been (1) the reduction of fishing effort in areas that are marginal for scallops and in areas of rugged terrain where safely towing fishing gear is challenging, and (2) an increase in overall catch rates by concentrating fishing effort in areas identifiable as scallop habitat, thus reducing costs associated with fishing. However, these maps have not yet been used to develop fine-scale management plans that are attuned to the spatial heterogeneity of the scallop populations.

Scallop grounds off of southwest Nova Scotia have recently been mapped using multibeam sonar technology in a joint project partnership of the Department of Fisheries and Oceans, Natural Resources Canada and the local scallop fishing industry. One of the major objectives of this project was to collect spatial information on scallop distribution, growth and size composition, bycatch data, as well as fine-scale bathymetry and surficial geology for the purposes of developing spatially-based fisheries management plans. There are two phases for the work on this objective. In the first phase, multibeam backscatter strength data will be interpreted in conjunction with geological and benthic sampling data to develop habitat maps of the area. At the same time, spatial patterns of scallop growth, densities and size composition obtained from concurrent scallop drag surveys will be related to these habitat attributes. All of this information does not, in itself, determine the objectives and approach of spatial management. The potential advantages of spatial management over the standard approach will be explored in the second phase of the project.

 

Overview of predictive modelling tools as an aid for the broad- and fine-scale mapping of European seabed habitats

 

Vera Van Lancker1, Bert Brinkman2, David Connor3, Eric De Oliveira4, Steven Degraer1, Bob Foster-Smith5, Paul Gilliland6, Peter Goethals1, Neil Golding3, Annika Mitchell7, Jacques Populus4, Els Verfaillie1, Wouter Willems1

 

1) Ghent University, Belgium

2) Alterra, The Netherlands

3) Joint Nature Conservation Committee, UK

4) Ifremer, France

5) Envision, UK

6) English Nature, UK

7) DARD Queen’s University, Ireland

 

A suite of modelling tools is being evaluated for the prediction of benthic marine habitats, related to both soft substrata and to rocky habitats. In particular, initiatives are being grouped within the framework of an European Union Interreg IIIb funded project called MESH (Mapping European Seabed Habitats) which aims to develop a first holistic seabed habitat map for NW Europe.

 

Initially, the modelling aims to provide maps for areas where biological data are scarce or not available. As such the main focus is on the use of the more widely available geophysical and hydrographic data which act as a surrogate for biological data. Various modelling initiatives are being undertaken at different scales and resolutions that are highly valuable for the development of a common modelling strategy that integrates both small and large-scale approaches.

 

A number of case studies will be presented, related both to intertidal as well as subtidal coastal shelf environments. Techniques that are being used in shelf environments are geostatistical modelling, artificial neural networks and regression, a combination of which will lead to a high resolution probability map of benthic habitats for the sandy Belgian continental shelf. Regression modelling is also being used to predict the distribution of mussel beds in the Wadden Sea and for some macrobenthic species on the Dutch continental shelf. Predictive modelling on intertidal rocky shores is presently focussed on predicting the distribution of seaweed communities. Using substratum, immersion time and wave exposure, distribution rules derived for each seaweed species are modelled using fuzzy logic. Another case study is modelling the occurrence of biogenic reefs of the honeycomb worm Sabellaria spinolosa. A data base on the environmental conditions for the known occurrence of Sabellaria is being constructed and analysed to build a profile. Generalised linear modelling and bayesian belief networks are being used as modelling technique to determine other locations that match this profile. On a broadscale level, the MESH Project aims to a further refinement of the marine landscape approach developed by Roff & Taylor (2000) and applied to UK waters by Golding et al. (2004) (see separate paper submitted to GeoHAB). This methodology captures a suite of geophysical and hydrographic parameters and validates the resultant model with the biological nature of the seabed.

 

With respect to the availability and detail of datasets per country, both a broadscale top-down and detailed bottom-up modelling approach are expected to be needed to meet the needs of both the scientific community and end-users in general.

 

Mapping the distribution of cold-water corals and sponges off the U.S. West Coast

Curt E. Whitmire, M.E. Clarke, and W.W. Wakefield

NOAA Fisheries – Northwest Fisheries Science Center, WA, USA

 

Cold-water corals (e.g., Orders Scleractinia, Antipatharia, Gorgonacea) and other biogenic structure-forming invertebrates (e.g., sponges) likely play important ecological roles in continental shelf and slope ecosystems and may be indicators of long-term environmental conditions. Despite growing interest from researchers, conservation organizations, and policymakers, a debate continues as to whether or not these organisms provide a structural component to essential fish habitat. To date, there exist no regional surveys of structure-forming invertebrates off the U.S. West Coast. However, an extensive database of observations on benthic invertebrates was compiled from regional bottom trawl surveys conducted by NOAA Fisheries over the past three decades. Although bottom trawls are not designed to target sessile invertebrates, over 1,500 catch samples of corals and sponges have been recorded. Our objectives for this study are to map the distribution of corals and sponges off the U.S. West Coast and use analytical results to assist in the design of comprehensive in situ surveys to investigate potential fish-invertebrate-habitat associations. In addition, this information can be used as a starting point to inform management decisions that are designed to protect biogenic habitats.

 

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