Demersal fish assemblages and their diversity on the Yucatan continental shelf: Gulf of Mexico

Spatial variation in demersal fish assemblages (86 degrees-92 degrees W) and depth (<100 m, 101-200 m) on the Yucatan Shelf were determined using data from eighteen sampling stations collected during two periods (November 2015; August 2016). Estimates of ecological parameters and dominant species were made, and any spatial and causal associations between fish species and environmental variables (temperature, salinity, depth, nutrients) were identified. Alpha and beta diversities were recorded for each spatial and depth gradient, and gamma diversity was estimated for the entire region. A total of 161 species were recorded (27 orders and 52 families), with Syacium papillosum being the dominant species due to its high biomass (10.3%), relative density (11.7%) and occurrence. Followed in dominance by Haemulon aurolineatum, Eucinostomus gula and Upeneus parvus. No inter-annual change in the fish assemblages was detected using multivariate analysis, however, differences were identified between geomorphic units by depth gradient. Canonical correspondence analysis showed that depth gradient was the principal factor affecting variation in fish community structure. Based on gamma diversity (202) and species richness (161 species) the study area appears in good health. The data generated constitute an invaluable baseline for quantifying future changes and impacts on this ecosystem's biodiversity. (C) 2019 Elsevier B.V. All rights reserved.