Nearshore exposure to Deepwater Horizon oil

Abstract

The Deepwater Horizon (DWH) oil spill affected more than 2000 km of shoreline. DWH oil entered the nearshore environment, stranding on shorelines as tar balls and/or emulsified oil, or forming submerged oil mats and integrating into nearshore sediments. The available chemistry data showed submerged sediments, especially within the first 50 m from oiled shorelines, displayed patchy distributions of elevated polycyclic aromatic hydrocarbon (PAH) concentrations in excess of ambient concentrations, which were quantified based on forensic findings establishing their source as being from the Macondo oil. Consistent with observed shoreline oiling conditions, PAH concentrations in the soils of affected Louisiana coastal wetlands were orders of magnitude higher than ambient concentrations, especially in locations along the seaward edge of the marsh. Both total and petrogenic PAHs decreased with distance from the shore in both inland and offshore directions. Although PAHs exhibited evidence of weathering over time, in the most heavily oiled areas, they continued to exceed ambient concentrations by orders of magnitude through fall of 2013.

Response of nearshore ecosystems to the Deepwater Horizon oil spill

“…The results of studies presented in the present Theme Section as well as other studies on the DWHOS encompass the documentation of lethal and sublethal effects of oil spills on individual taxa (see Baker et al 2017), spanning the full range of trophic levels from microbes (Dubinsky et al 2013) to marine mammals (Barron 2012, Schwacke et al 2014). Although many nearshore studies showed localized impacts of the DWHOS, not all nearshore studies indicated negative responses of key species (see Fodrie et al 2014).…”

“…Burns & Teal 1979, Fleeger & Chandler 1983, DeLaune et al 1984. Although prior studies allow for general predictions on the direction of species responses, the elucidation of injury pathways, quantification of injuries (Baker et al 2017, this Theme Section) and scaling of restoration (Peterson & Lipcius 2003) -all of which are necessary components of the Natural Resource Damage Assessment (NRDA) process -represented a fundamental challenge to marine ecologists investigating the DWHOS.…”

“…Anticipated recovery times of injured resources vary as a function of longevity of the species and impact on the habitats that the species rely upon (Baker et al 2017, Zengel et al 2017. In general, habitat degradation or loss as a consequence of oiling or response-related activities will affect multiple generations of taxa and persist until restoration becomes effective.…”

“…1), with an immense geographic footprint (1000s of km of shoreline oiled; Rouhani et al 2017, this Theme Section) and temporal scale (oil release for 87 d), and it challenged marine ecologists in designing assessments of its impacts. The DWHOS affected 2 different but connected ecosystems: the open ocean of the Gulf of Mexico and the nearshore environments of the northcentral Gulf of Mexico (Peterson et al 2012).…”

“…Baker et al (2017) provides the conceptual model adopted after the synthesis of results from the DWHOS. Such a conceptual model can also direct response action by prioritizing critical habitats in which oiling is likely to result in substantial habitat degradation or loss.…”