Diverse faunal groups inhabit deep-sea sediments over much of Earth's surface, but our understanding of how interannual-scale climate variation alters sediment community components and biogeochemical processes remains limited. The vast majority of deep-sea communities depend on a particulate organic carbon food supply that sinks from photosynthetically active surface waters. Variations in food supply depend, in part, on surface climate conditions. Proposed ocean iron fertilization efforts are also intended to alter surface production and carbon export from surface waters. Understanding the ecology of the abyssal sediment community and constituent metazoan macrofauna is important because they influence carbon and nutrient cycle processes at the seafloor through remineralization, bioturbation, and burial of the sunken material. Results from a 10-year study in the abyssal NE Pacific found that climate-driven variations in food availability were linked to total metazoan macrofauna abundance, phyla composition, rank-abundance distributions, and remineralization over seasonal and interannual scales. The long-term analysis suggests that broad biogeographic patterns in deep-sea macrofauna community structure can change over contemporary timescales with changes in surface ocean conditions and provides significant evidence that sediment community parameters can be estimated from atmospheric and upper-ocean conditions. These apparent links between climate, the upper ocean, and deep-sea biogeochemistry need to be considered in determining the long-term carbon storage capacity of the ocean.biogeochemistry ͉ community structure ͉ deep sea ͉ ecology ͉ macrofauna A ppreciating how climate can influence deep-sea communities and biogeochemical cycles is essential in evaluating how they may vary in the future. Current evidence suggests that climate change is resulting in significant alterations of oceanographic conditions worldwide including increased sea-surface temperatures, stronger stratification, and increased acidity (1, 2). The changing climate will likely also impact net primary production (1, 3-7) and the export of particulate organic carbon (POC) to the deep sea. Life on the seafloor depends upon this sinking POC and has a fundamental influence on the amount of carbon and nutrients that are remineralized or buried there. Ocean iron fertilization plans also project increases in surface production and POC export from surface waters, but fertilization impacts are poorly constrained (8, 9), especially for the deep-sea sediment community.Detailed studies of macrofauna, a major component of the sediment community, have been conducted at various locations and depths worldwide and have generally found higher abundances below areas with greater surface production (10-16). Abyssal food supply varies with distance from shore, depth, and surface productivity at basin scales. Previous studies that covered adequate spatial areas, however, understandably lacked long-term temporal perspective. Most spatial studies have effectively compa...
Individuals of an enteropneust, Tergivelum baldwinae n. gen., n. sp. were videotaped at a depth of about 4 km in the eastern Pacifi c and collected by a remotely operated vehicle. Th e living worms range in length from 9 to 28 cm and are dark brown anteriorly and beige posteriorly. Th e proboscis is shaped like a shallow dome, indented on either side by a laterodorsal fossa housing a prominent proboscis nerve. Th e collar comprises a thin transverse crest dorsally and two laterally projecting lips on either side of the mouth ventrally. Th e mouth is oriented parallel to the substratum and is fl anked by large left and right buccal muscles (contrasting with the rudimentary musculature elsewhere in the body). Th e respiratory pharynx of the trunk extends far anteriorly so that much of it lies dorsal to the mouth opening. Th e gill bars are not joined by synapticles. Th e laterodorsal body wall at the anterior extremity of the trunk extends as two conspicuous fl aps (back veils) that run posteriorly as unattached coverings over the anterior 30-50% of the trunk. On either side of the midline, the body wall of the trunk is extended as a narrow lateroventral fold. Within
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