Benthic Index for Estimating Food Availability in Two Soft Bottoms Fishing Areas

Based on the role of mollusks in trophic webs, this study aimed to implement a benthic food availability index (BFAI) estimated from soft-bottom benthic mollusks in fishing areas. Two lobsters fishing regions, Caibarien and Batabano, were sampled. The design of BFAI was based on the densities, biomasses, and species richness of mollusks at eight sites in each region. Mollusks and benthos communities (> 4 mm) were sampled by dredging. Spatial effectiveness of BFAI was tested comparing among sites and regions. Temporal effectiveness was tested comparing BFAI between Past period (1981–1985 in Batabano and 1989–1990 in Caibarien) and Current data (2015 in Caibarien and 2015–2018 in Batabano). BFAI was regressed with Shannon-Weiner diversity and species richness indices. BFAI average in Caibarien (2015) was 0.90. In Batabano it was 0.64 and 1.09 for 2015 and 2018 respectively. In both regions BFAI varied among sites and shows a significant temporary decrease, going from "Good" in the Past to "Fair" in the Current. No differences were found between regions, but spatial distribution of BFAI values ​​corresponds to the biotic potential (density, biomass, and species richness of benthos), which suggests the certainly of BFAI detecting the benthic community variations that affect the food availability. Regression coefficients were significant in more than 60% of the cases being between 0.701 and 0.978. BFAI showed greater values where lobsters catches have been usually higher, it means that BFAI constitute another environmental explanation for lobster abundance decrease at natural fishing areas.