Habitat Suitability Modelling of Shallow Water Structure Forming Communities in the Big Bend Region of Florida's Northeastern Gulf of Mexico

Hardbottom habitats in the Big Bend Region of the Gulf of Mexico are the foundation for structure-forming species, such as corals and sponges. These structure forming communities (SFC) provide important ecological services; they serve as spawning grounds, feeding grounds, and as refugia and nurseries for a diverse complex of seasonally and ontogenetically mobile fish and invertebrate species, many of which are important contributors to commercial and recreational fisheries. Knowledge of the extent of such hardbottom communities is an important tool for monitoring species recruitment success, stock assessments, and protection from over-exploitation. Modelling techniques can be used to evaluate the habitat suitability for SFC within this region, as well as elucidate the main factors driving the measure of suitability. The Big Bend Region is understudied, lacking comprehensive data on species and community presence. Using presence data for six abundant and long-lived taxa (2 stony corals, 3 sponges, and gorgonians), a habitat suitability model was constructed with the presence-only modelling technique Maxent, to describe the suitability of habitat for SFC in the Big Bend Region. Presence records were collected from in-situ surveys of suspected hardbottom habitat outside of Apalachicola Bay and from the 2010-2014 NOAA Fisheries reef fish surveys for the same region. Records were correlated with environmental covariates and compared against randomly sampled faux-absence points to test their effects on habitat suitability. Results of the model predicts that over 944 km2 of suitable habitat area exists between Port St. Joe and St. Marks. The model exceeded random performance, and found that northward current velocity, salinity, terrain type, and depth are the most important variables contributing to SFC habitat. Knowledge regarding the extent of these communities can elucidate factors that influence the fitness of fish species in the GOM, and ultimately inform species management.