Taxonomic resolution and biodiversity evaluations for deep-sea fish assemblages in a pelagic ecosystem of the northern Gulf of Mexico

Oceanic fish biodiversity is extremely rich in the Gulf of Mexico, which is deemed one of four “hyperdiverse” mesopelagic (200 – 1000 m depth) ecoregions in the World Ocean. Although the mesopelagic Gulf of Mexico has been significantly studied over the past decade, there is a need for more effective environmental monitoring for these large biomes. Taxonomic inventories are difficult to create and complete, particularly after a disturbance has occurred, such as the Deepwater Horizon Oil Spill in 2010. Here, we examine mesopelagic fish data collected in 2010-2011 as part of the Natural Resource Damage Assessment following the Deepwater Horizon Oil Spill. The aim of this study is to compare a series of multivariate analyses collected from the deep pelagic realm at different taxonomic resolutions to determine the utility of using higher taxonomic level data to inform future deep-sea ecosystem disturbance assessments. Species-level data were combined at the genus, family, and order level to emphasize the effect of taxonomic resolution on assemblage and biodiversity. Results to date suggest community-level patterns at genus-level structure analyses are similar to species-level results, but decrease in similarity at family and order level. The results from this study provide insight for decision makers involved in future monitoring of oceanic regions.