Pan-Atlantic Comparison of Deep-Sea Macro- and Megabenthos

Abstract

Deep-sea benthic fauna is vital for a well-functioning marine ecosystem but is increasingly under threat from a changing environment. To monitor and conserve this fauna, an understanding of their large-scale spatial and bathymetric distribution and their environmental drivers is necessary. In this study, we conduct a multivariate analysis on abundance benthic fauna data collected at the phylum and multitaxon levels using an epibenthic sledge (EBS) across the Atlantic, and identify the environmental factors that affect such data. Our findings show a decrease in abundance with depth in most of the Atlantic but find relatively heterogeneous abundances with depth within the Southern Ocean. Principal component analyses indicate differences in environmental conditions south of the Antarctic Polar Front (~52° S), outlining contrasts in the quantities of macronutrients and physical factors. Despite this, community composition seemed markedly similar throughout the Atlantic with the Antarctic Circumpolar Current seemingly not affecting benthic community composition for higher taxonomic levels. Those differences that did occur were largely caused by benthic chlorophyll, benthic iron, and surface silicate through a Bio-ENV. Overall, we argue that further large-scale spatial and bathymetric distribution studies are important amid environmental changes that are driving shifts in benthic community abundance and composition.