NEW PAPER: Synthesis of the Open-Ocean Gulf of Mexico after the Deepwater Horizon Oil Spill

The decade after the Deepwater Horizon oil spill has seen an unprecedented level of research investment into the ecosystems of the northern Gulf of Mexico. In our new open-access paper, out now in Frontiers in Marine Sciences (doi: 10.3389/fmars.2022.753391), we synthesize over ten years of research into the fauna of the offshore realm, the Gulf's single largest 'ecotype' by volume.

Left: Pantropical Spotted Dolphin. Credit: Marie C. Hill. From: https://www.fisheries.noaa.gov/species/pantropical-spotted-dolphin. Right: Diaphus subtelis: a typical lanternfish captured during the DEEPEND program from the deep Gulf of Mexico. Image by Dante Fenolio/DEEPEND

In our review, we consider the likely vulnerability and resilience of oceanic fauna, from plankton to marine mammals, and consider the weight of evidence for impacts and/or damage in the years following the oil spill considering that in many cases, pre-spill data simply are not available. DEEPEND authors are amongst the authors, and we highlight a key finding that the abundances of many deep-living micronekton taxa have declined substantially in the Gulf since our first surveys in 2011. Thanks to analyses conducted by Dr. Rosanna Milligan, we do not believe that this decline is associated with changing abiotic conditions in the Gulf, and there is no evidence that there have been substantial changes in primary productivity in that time either. However, we note declines in oceanic stenellid dolphins over this same time period - whether this decline is related to declines in our micronekton, which they often feed on, or to some other effects, we cannot say at this stage. No evidence of recovery is evident amongst declined taxa so far, and overall, the evidence we present here suggests that the oceanic Gulf ecosystem may be quite vulnerable to impacts, and relatively slow to recover, even amongst those taxa (like micronekton) that have relatively short generation times and might be expected to recover faster.

Schematic of the open-ocean ecosystem of the northern Gulf of Mexico. Solid arrows associated with key taxa represent active flux (vertical migrations); dashed arrows indicate passive flux (sinking). Nekton = fishes, cephalopods, and large pelagic crustaceans. Note: seabirds not treated in synthesis due to lack of time-series data but included here to represent aerial-to-deep-pelagic connectivity. From: 10.3389/fmars.2022.753391

This paper is one of six in a special issue of FMARS, each of which assesses the vulnerability and resilience of a different "ecotype", from deep-benthic fauna, to coastal living marine resources. The full special issue can be accessed here: https://www.frontiersin.org/research-topics/13809/vulnerability-and-resilience-of-marine-ecosystems-affected-by-the-deepwater-horizon-oil-spill/magazine