Cold seep benthic communities in the Japan subduction zones: spatial organization, trophic strategies and evidence for temporal evolution

Abstract

Submersible exploration of the Japan subduction zones has revealed benthic communities dominated by clams (Calyptogena spp.) around sed~ment porewater seeps at depths from 3850 to 6000 m. Photographic and video records were used to produce microcartographlc reconstructions of 3 contrasting cold seep sites. Spatial and abundance relations of megafauna lead us to propose several hypotheses regard~ng the ecological functioning of these cold seep communities. W e dlst~nguish between the likely direct use of reducing substances in venting fluids by Calyptogena-bacteria symbioses and indirect usage by accompanying abyssal species not known to harbour symbionts. Microdistribution and known or presumed feedmg modes of the accompanying species indicate 2 different sources of organic matter enrichment within cold seep sites: organic debris originating from bivalve colonies, and enrichment of extensive areas of surrounding surface sediments where weaker, more hffuse porewater seepage may support chemosynthetic production by free-living bacteria. The occurrence of colony-like groupings of empty Calyptogena valves indicates that cold seeps are ephemeral, with groups of living clams, mixed living and dead clams, and empty dissolving shells marlung the course of a cycle of porewater venting and offering clues to the recent history of cold seep activity.

Characteristics of meiofauna in extreme marine ecosystems: a review

“…The first cold seep was discovered in 1979 on the active margin of San Clemente in California (USA) (Sibuet and Olu 1998). Since then, other cold seeps have been found on the passive margin of Florida (USA) in the Gulf of Mexico, on the subduction zones of Oregon (USA) and Japan, and the Barbados accretionary prism (Juniper and Sibuet 1987;Olu et al 1996). In Europe, cold seeps have also been found on the Norwegian margin, in the Gulf of Cadiz and the Mediterranean Sea and references therein; Ritt et al 2010;Zeppilli et al 2011Zeppilli et al , 2012.…”

The deepest chemosynthesis-based community yet discovered from the hadal zone, 7326 m deep, in the Japan Trench

“…In shallower (from 4981 to 5938 m) cold seep communities in the Japan Trench (dominated by Calyptogena phaseoliformis), numerous actinians, buccinid and rissoacean gastropods, tubedwelling polychaetes, capreilid amphipods, and swimrning holoihurians (Pem'agone sp.) are consistenily associated with Calyptogena aggregations (Juniper & Sibuet 1987, Ohta & Laubier 1987, Sibuet et al 1988), but they were not observed in these thyasirid aggregations. The tubes observed at this site were curved and sparsely distributed, while those tubes commonly observed within Calyptogena-dominated sites are straight and densely packed.…”

“…Sulfide for these thyasirid aggregations may be produced in this way, using methane as a n energy source. The distnbution of this comrnunity seems more restncted than seep communities in other areas, such as Sagami Bay (Hashimoto et al 1989, the Nankai accretionary prism (Juniper & Sibuet 1987, Ohta & Laubier 1987, Sibuet et al 1988), Monterey Bay (Barry et al 1996), the Peruvian active margin (Olu et al 1996a) and the Barbados prism (Olu et al 199613). Detailed observations show that the newly discovered communities differ in other aspects as weil.…”

“…Deep-sea cold seep communilies have been observed in 24 areas worldwide at depths ranging from 400 to 6000 m (Sibuet & Olu 19%31. Examples include subduction zones (Okutani & Egswa 1985, Kulm et al 1986, Juniper & Sibuet 1987, OIU et al 1996a,b, Suess et al 1998, groundwater seeps (Hecker 1985, Barry et al 1996, hydrocarbon seeps (Kennicutt et al 1985) and shallow rnethane seeps 150 m deep (Dando et al 1991). Seep communities typically have high biomass.…”

“…The Japan Trench was formed by the subduction of the Pacific plate beneath the North Amencan or Okhotsk plate (Seno & Sakurai 1996). A broad-based study of geologic and biologic features within the Japan Trench was started under a Japan-French cooperative program (the KAIKO Project) using surveys from the French manned submersible 'Nautile' (KAIKO I Research Group 1986, Juniper & Sibuet 1987, Ohta & Laubier 1987, Sibuet et al 1988). The deepest chemosynthesis-based community known prior to this report was discovered during a dive of the Japanese submersible 'Shinkai 6500', on the Sannku Escarpment slope of Ihe Japan Trench at a depth of 6437 m (Ogawa et al 1996) (Fig.…”