Evidence of Rapid Functional Benthic Recovery Following the Deepwater Horizon Oil Spill

Abstract

The 2010 Deepwater Horizon incident was a massive deep-sea oil spill and resulted in deposition of hydrocarbons at the seafloor surface. Soft sediment benthic macrofauna provide critical global ecosystem services, and little is known about their recovery trajectories from similar disturbances in the deep sea. Recent publications report an initial opportunistic benthic infaunal response and predict 50−100 years for recovery of species-level diversity, abundance, and composition. Sediment profile and plan view imaging data collected at depths from 1040 to 1689 m in 2011 and 2014 not only confirm this opportunistic response but also indicate further stages of functional benthic recovery. The recovery trajectory mimicked benthic succession following organic enrichment that is widely recorded in coastal systems but not the deep sea. Bioturbating taxa were present deep in the sediment column in both years. In 2014, a decline in the relative abundance of opportunistic taxa and a positive rebound in the apparent redox potential discontinuity depth, an integrated measure of biogeochemical functioning, were recorded. These results suggest that bioturbation-mediated microbial degradation is a plausible mechanism by which rapid functional benthic recovery occurred. With oil and gas extraction prevalent in the deep sea, improving the understanding of benthic recovery in these environments is critical.

Vulnerability and resilience of living marine resources to the Deepwater Horizon oil spill: an overview

“…At least two major chronic "reservoirs" of DWH oil/dispersant residues remain in the environment (deep benthic, coastal wetlands) with surprisingly little ongoing weathering of oil (i.e., still toxic) in some cases (e.g., Turner et al, 2019a). In the case of the deep offshore benthic oil reservoir, it may take 50-100 years before DWH oil is sufficiently buried to be unavailable to invertebrate and vertebrate bioturbators (Montagna and Girard, 2020;Schwing et al, 2020), although by some metrics a degree of functional diversity had returned to affected areas by 2014 (Guarinello et al, 2022). The deep ocean communities in the pelagic (Romero et al, 2018) and benthic realms (Schwing et al, 2020) are highly diverse biomes that are particularly vulnerable to oil spills and possibly to mitigation approaches such as the use of sub-surface dispersant injection.…”