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Antipatharian Distribution and Suitability Mapping in the Mesophotic Zone of the Northwestern Gulf of Mexico

Project Goal

To document the diversity and distribution of black corals and associated fauna in the northwestern Gulf of Mexico, validate the process of making in situ identifications of mesophotic black coral species, and generate, validate, and test habitat suitability models, using both presence-only and presence-absence techniques, for their predicted distribution in the region.

Geographic Location

Northwestern Gulf of Mexico

Approach

Black coral specimens in the region were collected, with initial in situ identification based on current literature. Specimen identifications were then confirmed or rejected in the laboratory using traditional morphological techniques. Specimens were also examined for associated fauna, which were documented, removed, and identified. Habitat suitability models were generated using presence only (MaxEnt) and presence absence techniques (Boosted Regression Trees), based on historical data collected by the Flower Garden Banks National Marine Sanctuary (FGBNMS). Model performance evaluated using cross validation, and compared using out of sample accuracy measures of percent accuracy and Cohenís kappa coefficient.

Results

The validation of in situ identifications of black coral species was evaluated, and recommendations for species identifications and species groupings were made. The majority of species identified in this study have been previously observed in the northwestern Gulf of Mexico. However, three morphotypes were collected, including Stichopathes sp., Tanacetipathes sp., cf. T. paula and Acanthopathes sp., cf A. thyoides, that could not be assigned to any nominal species. Each of these morphotypes, represented by a single colony, possessed or lacked features that would allow for definitive species identification and will require further taxonomic study. Black coral associated fauna were documented, supporting known associations and documenting potentially new associations and species.

Habitat suitability models for the distribution of black coral species at selected banks in the northwestern Gulf of Mexico were generated. Presence-only models made using the MaxEnt modeling program were compared to presence-absence models made using Boosted Regression Tree modeling techniques. Presence-absence models were documented to have greater predictive accuracy than the presence-only models, which showed evidence of model overfitting. The model was projected to five similar salt-dome features in the region, highlighting extensive habitat for multiple black coral species in these unexplored habitats. This study presents habitat suitability maps as a testable hypothesis for black coral distribution in the mesophotic zone of this region

Importance to Management

The model will be directly applied to current research activities and partnerships at the FGBNMS, and help focus research, management, and conservation efforts.

Fiscal Year 2012 Funding

$39,900

Point of Contact

Marissa F. Nuttall, Marissa.Nutall@noaa.gov