Temporal Changes in the Micronektonic Crustacean Assemblage in the Gulf of Mexico Since the Deepwater Horizon Oil Spill

Abstract

This talk will present data from a series of cruises conducted in 2011 (ONSAP), one year after the Deepwater Horizon oil spill, and cruises conducted in 2015-2017 (DEEPEND), five to seven years after the spill. This analysis includes the dominant taxa, in terms of both abundance and biomass, that make up the micronektonic crustacean assemblage in this area - the Euphausiacea (families Euphausiidae and Bentheuphausiidae) and the Decapoda (families Benthesicymidae, Sergestidae, Pandalidae and Oplophoridae). There has been a dramatic decrease in abundance for the assemblage as a whole between the ONSAP and DEEPEND cruises, with the Euphausiacea declining by 70-80% and the Decapoda declining by ~50%. There are no pre-spill data with which to compare these numbers to demonstrate a cause and effect, but the magnitude of the decline cannot be explained by measured natural variability. There are differences in vulnerabilities of the various families as indicated by differences in the magnitude of their declines, and differences in life histories and food preferences will be discussed as possible explanations for these observations