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 km2. 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 km2. 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.

The second paper of the series about Ampharetidae from Japan includes twelve species of four genera with elevated and modified notopodia,

Sampling methods for benthic meiofauna and macrofauna assessments on the northern Gulf of Mexico continental slope and deep sea were compared. For meiofauna, a core with an inner diameter of 5.1 cm is recommended for yielding an appropriate sample size. Meiofauna are concentrated in the uppermost 2 cm sediment layer, so the top 3 cm are sufficient to sample. Macrofauna penetrate deeper and the top 10 cm are sufficient. Smaller sieves capture more organisms so 45 μm for meiofauna, and 300 μm for macrofauna, is recommended. On average, 88% of meiofauna were extracted in the Ludox fraction compared to the total of both Ludox and the sediment pellet. Box corers and multiple corers were compared for estimating macrofauna and meiofauna metrics. Multicorers are recommended for quantitative assessments, but box corers are useful for qualitative studies that require capturing more diversity. Box cores underestimate macrofauna abundance by 2.9 times. While the larger box core captures more species resulting in higher diversity estimates, it is low relative to the 24 times larger area sampled. The multicorer preserves vertical distribution. Because meiofauna are sampled from subcores, there is little difference between the two devices for estimating meiofauna metrics. Replicate multicore samples (i.e., deployments) do not add substantially to our understanding of the variance of species richness or abundance, thus to describe the spatial footprint of macrofauna community structure, it is recommended that resources should be used to sample more stations over a larger area rather than multiple replicates at fewer stations.

Terebellomorph polychaetes are reported from hydrothermal vents and cold seeps collected in the Pacific and Atlantic Oceans. Two new species of Terebellidae,Neoamphitrite hydrothermalissp. nov. andStreblosoma kaiasp. nov., are described from hydrothermal vents of the western Pacific. These are the first terebellid species described from hydrothermal vents. New records from hydrothermal vents and cold seeps and new geographical records are presented for nine additional species belonging to Ampharetidae, Alvinellidae, Terebellidae and Trichobranchidae. A synoptic table with diagnostic characters for all species of the genusStreblosomaSars, 1872 is provided. Keys for all terebellomorph species currently known from hydrothermal vents and cold seeps, respectively, are included. Additionally the new combinationNeoamphitrite pachyderma(Hutchings & Glasby, 1988) comb. nov. is proposed.

Five species of Ampharete are reported from Japan. Two species, Ampharete ampullata sp. nov., and Ampharetecinnamomea sp. nov., are newly described, and Ampharete falcata, is newly recorded from the North Pacific. Severalmorphological characters are reviewed and their value for taxonomy and systematics is discussed. A schematic diagram of the anterior end of ampharetid polychaetes, which may serve as the species’ “ID card”, is introduced.