TEMPORAL TRENDS IN DEEP-SEA CORAL BIODIVERSITY AND BIOGEOGRAPHY, GULF OF MEXICO AND US WEST ATLANTIC

Characterizing deep-sea coral biodiversity is an integral step in evaluating the current state of the deep-sea ecosystem and in assessing vulnerability to anthropogenic factors. Thousands of deep-sea coral records are compiled in the publicly accessible NOAA database, but few large-scale analyses of deep-sea coral biodiversity or biogeography have been conducted. This study tested persistence of coral biodiversity across shelf and slope environments and assessed biodiversity changes and biogeographic differences across regions. Analyzed records consisted of deep-sea coral occurrences that were verifiable for taxonomy, depth, location, and time. Approximately 24,080 records of coral occurrences were gleaned, categorized to shelf (60-200 m) and to slope (201-2000 m) depths, subdivided into Caribbean, Gulf of Mexico, and US West Atlantic regions, and binned into time intervals of pre-1960, and decadal intervals thereafter to the 2010’s.

Data were most robust across all time bins for slope depths in the Gulf and the US West Atlantic, and subsequent analyses focused on these subsets. In both regions, biodiversity decreased sharply through time following 1990 for all examined taxonomic levels (family, genus, and species), with a larger biodiversity decrease in the Gulf than in the US West Atlantic. Caryophylliidae and Oculinidae were the most persistent families in the Gulf and US West Atlantic, and Lophelia pertusa and Madrepora oculate were the most persistent species. Dendrophylliidae and Enallopsammia profunda were persistent in the US West Atlantic but not in the Gulf. Overall, Gulf slope corals exhibited a greater decrease in biodiversity than in the US West Atlantic.

This regional and temporal analysis capitalized on the power of NOAA records to improve understanding of deep-sea coral biodiversity and biogeography and to inform future conservation efforts.