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Using Cordell Bank as a Model to Conduct Fine-Scale Deep-Sea Coral Predictive Habitat Modeling

Project Goal

Use existing observations of coral on Cordell Bank to develop a model for understanding habitat relationships and allow predictions of species occurrence.

Geographic Location

Cordell Bank, northern California

Approach

Five years of video from the Delta submersible on the Cordell Bank was reviewed,  looking at distribution and abundance of the hydrocoral (Stylaster spp.) and gorgonian coral (Swiftia spp.)as it related to various seafloor features like substrate type, depth and slope. Presence and absence of corals were compared with fine-scale seafloor mapping information to provide assessments of habitat relationships and allow predictions of species occurrence.

Results

Hydrocorals and gorgonians occupy different niches on Cordell Bank. Hydrocorals (Stylaster spp.) are restricted to a smaller area on the Bank and prefer hard, shallow, high slope areas while gorgonians (Swiftia spp.) are more broadly distributed over a variety of substrates in deeper, low sloping environments. Depth, slope, and broad scale topographic position index are the best predictors for the presence of Stylaster spp. and Swiftia spp. on Cordell Bank.

Importance to Management

Preliminary results of predicted locations of coral presence have been used to meet several management needs at Cordell Bank National Marine Sanctuary. First, results were used to choose a target location for the placement of an oceanographic instrument mooring to minimize impact to sensitive benthic communities, by finding locations with a low probability of deep sea coral presence. Next, model results were assessed in exploratory efforts to establish monitoring locations of benthic communities on Cordell Bank. Since Stylaster spp. and Swiftia spp. occupy such different habitat niches, they are indicators of different benthic community types. Further, locations of high Stylaster spp. abundance are being considered for focused studies of the impacts of ocean acidification on deep-sea corals at Cordell Bank. Modeling results have also been useful for considering locations that would be appropriate for testing proposed experimental fishing techniques to minimize the potential for damaging sensitive benthic communities. Lastly, modeling results will be used to illustrate the importance of the existing essential fish habitat conservation zone that prohibits the use of bottom contact fishing gear on Cordell Bank for protecting sensitive biogenic habitats for groundfish. Overall, these habitat models aid our ability to make informed management decisions regarding these sensitive and diverse communities within a national marine sanctuary.

Links

Summary Report available at: http://cordellbank.noaa.gov/science/research.html#coral (under “Reports”)

Fiscal Year 2009 Funding

$15,000

Point of Contact

Dan Howard, Dan.Howard@noaa.gov