Fallout plume of submerged oil from Deepwater Horizon

Abstract

Significance Following the sinking of the Deepwater Horizon in the Gulf of Mexico an unprecedented quantity of oil irrupted into the ocean at a depth of 1.5 km. The novelty of this event makes the oil’s subsequent fate in the deep ocean difficult to predict. This work identifies a fallout plume of hydrocarbons from the Macondo Well contaminating the ocean floor over an area of 3,200 km 2 . Our analysis suggests the oil initially was suspended in deep waters and then settled to the underlying sea floor. The spatial distribution of contamination implicates accelerated settling as an important fate for suspended oil, supports a patchwork mosaic model of oil deposition, and frames ongoing attempts to determine the event’s impact on deep-ocean ecology.

Community response of deep-sea soft-sediment metazoan meiofauna to the Deepwater Horizon blowout and oil spill

“…The data presented by Fisher et al (2014) corroborate the broader spatial pattern of enrichment presented here. Multiple pathways exist by which oil-derived carbon could have entered deep-sea food webs (Montagna et al 2013), but the recently published 'fallout plume' hypothesis (Valentine et al 2014) suggests higher fluxes of oiled bacterial flocculants to the seafloor over the spatial extent of the present study. The fallout plume may have been fueled by Colwellia (Baelum et al 2012) or other endogenous bacterial flocculation.…”

“…This community response indicates that the DWH deep-sea impacts represent a balance between enrichment and toxicity, a phenomenon that is consistent with prior investigations of drilling-related activities (Montagna & Harper 1996) and oil spill effects (Giere 1979). A similar enrichment response following the DWH spill was documented in soft-sediment meiobenthic communities that were sampled near deep-water corals (Fisher et al 2014), and in reasonably close proximity to the stations sampled as part of the present study. The data presented by Fisher et al (2014) corroborate the broader spatial pattern of enrichment presented here.…”

“…A similar enrichment response following the DWH spill was documented in soft-sediment meiobenthic communities that were sampled near deep-water corals (Fisher et al 2014), and in reasonably close proximity to the stations sampled as part of the present study. The data presented by Fisher et al (2014) corroborate the broader spatial pattern of enrichment presented here. Multiple pathways exist by which oil-derived carbon could have entered deep-sea food webs (Montagna et al 2013), but the recently published 'fallout plume' hypothesis (Valentine et al 2014) suggests higher fluxes of oiled bacterial flocculants to the seafloor over the spatial extent of the present study.…”

“…Oil may have also moved in either surface or sub-surface layers due to onshore− offshore transport of oil-laden particles, sinking of heavier oil byproducts resulting from the burning of oil, or settling of oil−mud complexes resulting from the injection of drilling mud during top-kill operations (UAC 2010). There is also increasing data to support the hypothesis that bacterial blooms in surface or mid-water environments resulted in flocculation that may have captured suspended oil and increased oil transport rates to deep-sea benthic habitats (Valentine et al 2014). In addition, drill cuttings, drill fluids, and other containment fluids commonly used during offshore oil-drilling operations (Neff et al 1987(Neff et al , 2005 may have been released and deposited to the bottom during the blowout event.…”

“…These estuarine and shallow-water coastal investigations have documented impacts to salt marshes and associated communities (McCall & Pennings 2012, Silliman et al 2012, and benthic microbial and eukaryote communities (Kostka et al 2011, Bik et al 2012, Lu et al 2012, Mason et al 2012, and there has been extensive reporting of water-column microbial response to the DWH-derived hydrocarbons (Kessler et al 2011, Valentine et al 2014. However, few studies to date have documented deep-sea benthic impacts of the DWH oil spill (White et al 2012, Montagna et al 2013, Fisher et al 2014.…”