The expanded footprint of the Deepwater Horizon oil spill in the Gulf of Mexico deep-sea benthos.

The 2010 Deepwater Horizon blowout off the coast of Louisiana caused the largest marine oil spill on record. Samples were collected 2-3 months after the Macondo well was capped to assess damage to macrofauna and meiofauna communities. An earlier analysis of 58 stations demonstrated severe and moderate damage to an area of 148 km2. An additional 58 archived stations have been analyzed to enhance the resolution of that assessment and determine if impacts occurred further afield. Impacts included high levels of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH) in the sediment, low diversity, low evenness, and low taxonomic richness of the infauna communities. High nematode to copepod ratios corroborated the severe disturbance of meiofauna communities. Additionally, barium levels near the wellhead were very high because of drilling activities prior to the accident. A principal component analysis (PCA) was used to summarize oil spill impacts at stations near the Macondo well, and the benthic footprint of the DWH oil spill was estimated using Empirical Bayesian Kriging (EBK) interpolation. An area of approximately 263 km2 around the wellhead was affected, which is 78% higher than the original estimate. Particularly severe damages to benthic communities were found in an area of 58 km2, which is 142% higher than the original estimate. The addition of the new stations extended the area of the benthic footprint map to about twice as large as originally thought and improved the resolution of the spatial interpolation. In the future, increasing the spatial extent of sampling should be a top priority for designing assessment studies.

Temporal patterns of Deepwater Horizon impacts on the benthic infauna of the northern Gulf of Mexico continental slope.

The Deepwater Horizon oil spill occurred in spring and summer 2010 in the northern Gulf of Mexico. Research cruises in 2010 (approximately 2-3 months after the well had been capped), 2011, and 2014 were conducted to determine the initial and subsequent effects of the oil spill on deep-sea soft-bottom infauna. A total of 34 stations were sampled from two zones: 20 stations in the "impact" zone versus 14 stations in the "non-impact" zone. Chemical contaminants were significantly different between the two zones. Polycyclic aromatic hydrocarbons averaged 218 ppb in the impact zone compared to 14 ppb in the non-impact zone. Total petroleum hydrocarbons averaged 1166 ppm in the impact zone compared to 102 ppm in the non-impact zone. While there was no difference between zones for meiofauna and macrofauna abundance, community diversity was significantly lower in the impact zone. Meiofauna taxa richness over the three sampling periods averaged 8 taxa/sample in the impact zone, compared to 10 taxa/sample in the non-impact zone; and macrofauna richness averaged 25 taxa/sample in the impact zone compared to 30 taxa/sample in the non-impact zone. Oil originating from the Deepwater Horizon oil spill reached the seafloor and had a persistent negative impact on diversity of soft-bottom, deep-sea benthic communities. While there are signs of recovery for some benthic community variables, full recovery has not yet occurred four years after the spill.

Ampharetidae (Annelida: Polychaeta) from cold seeps off Pakistan and hydrothermal vents off Taiwan, with the description of three new species.

The new ampharetid species Eclysippe yonaguniensis sp. nov. and Glyphanostomum bilabiatum sp. nov. from the Yonaguni Knoll IV hydrothermal field off the coast of Taiwan and Pavelius makranensis sp. nov. from the cold seeps in the Makran accretionary prism off the coast of Pakistan are described. Amage cf. ehlersi Reuscher, Fiege & Imajima, 2015 and Anobothrus dayi Imajima, Reuscher & Fiege, 2013 are newly recorded from the Yonaguni Knoll IV hydrothermal field.

Deep-sea benthic footprint of the deepwater horizon blowout.

The Deepwater Horizon (DWH) accident in the northern Gulf of Mexico occurred on April 20, 2010 at a water depth of 1525 meters, and a deep-sea plume was detected within one month. Oil contacted and persisted in parts of the bottom of the deep-sea in the Gulf of Mexico. As part of the response to the accident, monitoring cruises were deployed in fall 2010 to measure potential impacts on the two main soft-bottom benthic invertebrate groups: macrofauna and meiofauna. Sediment was collected using a multicorer so that samples for chemical, physical and biological analyses could be taken simultaneously and analyzed using multivariate methods. The footprint of the oil spill was identified by creating a new variable with principal components analysis where the first factor was indicative of the oil spill impacts and this new variable mapped in a geographic information system to identify the area of the oil spill footprint. The most severe relative reduction of faunal abundance and diversity extended to 3 km from the wellhead in all directions covering an area about 24 km(2). Moderate impacts were observed up to 17 km towards the southwest and 8.5 km towards the northeast of the wellhead, covering an area 148 km(2). Benthic effects were correlated to total petroleum hydrocarbon, polycyclic aromatic hydrocarbons and barium concentrations, and distance to the wellhead; but not distance to hydrocarbon seeps. Thus, benthic effects are more likely due to the oil spill, and not natural hydrocarbon seepage. Recovery rates in the deep sea are likely to be slow, on the order of decades or longer.

Ampharetidae (Annelida: Polychaeta) from Japan. Part II: Genera with elevated and modified notopodia.

The second paper of the series about Ampharetidae from Japan includes twelve species of four genera with elevated and modified notopodia, Anobothrus Levinsen, 1884, Sosane Malmgren, 1866 (including species of the synonymized genera Muggoides Hartman, 1965, Sosanopsis Hessle, 1917, and Genus A sensu Uebelacker 1984), Tanseimaruana gen. nov., and Zatsepinia Jirkov, 1986. Tanseimaruana gen. nov. is related to Amphicteis Grube, 1850, but lacks prostomial glandular ridges and has a velum-like dermal outgrowth with two pairs of lobes across the dorsum of the first abdominal unciniger. The new genus comprises Tanseimaruana vestis comb. nov. (Hartman, 1965) (formerly Amphicteis vestis) and T. boninensis sp. nov. Seven additional new species, Anobothrus dayi sp. nov., A. fimbriatus sp. nov., A. flabelligerulus sp. nov., Sosane brevibranchiata sp. nov., Sosane trigintaduo sp. nov., S. uebelackerae sp. nov. (formerly Genus A sensu Uebelacker), and Zatsepinia jirkovi sp. nov., are described. Sosane cf. cinctus (Hartman, 1965), Sosane wireni (Hessle, 1917), and Zatsepinia rittichae Jirkov, 1986, all species previously known from the North Atlantic, are recorded from the North Pacific for the first time. A phylogenetic analysis of Sosane (including the synonymized genera Mugga Eliason, 1955, Muggoides, Sosanopsis, and Genus A sensu Uebelacker) suggests monophyly of the genus with Lysippe Malmgren, 1866 as sister taxon, and a monophyletic clade [Sosane cinctus, Sosane uebelackerae sp. nov., Mugga spp.] within Sosane. The monotypic genus Melinnata Hartman, 1965 has been found indeterminable.