HR: 1340h
AN: OS43A-0989    [Abstracts]
TI: Macrofauna of shallow hydrothermal vents on the Arctic Mid-Ocean Ridge at 71N
AU: * Schander, C
EM: christoffer.schander@geo.uib.no
AF: Centre for geobiology, University of Bergen, Norway, Allegaten 41, Bergen, 5007, Norway
AU: * Schander, C
EM: christoffer.schander@geo.uib.no
AF: Department of biology, University of Bergen, Norway, P.O. Box 7800, Bergen, 5020, Norway
AU: Rapp, H T
EM: hans.rapp@bio.uib.no
AF: Department of biology, University of Bergen, Norway, P.O. Box 7800, Bergen, 5020, Norway
AU: Pedersen, R B
EM: rolf.pedersen@geo.uib.no
AF: Centre for geobiology, University of Bergen, Norway, Allegaten 41, Bergen, 5007, Norway
AU: Pedersen, R B
EM: rolf.pedersen@geo.uib.no
AF: Department of Earth Science, University of Bergen, Norway, Allegaten 41, Bergen, 5007, Norway
AB: Deep-sea hydrothermal vents are usually associated with a highly specialized fauna and since their discovery in 1977, more than 400 species of animals have been described. Specialized vent fauna includes various animal phyla, but the most conspicuous and well known are annelids, mollusks and crustaceans. We have investigated the fauna collected around newly discovered hydrothermal vents on the Mohns Ridge north of Jan Mayen. The venting fields are located at 71°N and the venting takes place within two main areas separated by 5 km. The shallowest vent area is at 500-550 m water depth and is located at the base of a normal fault. This vent field stretches approximately 1 km along the strike of the fault, and it is composed of 10-20 major vent sites each with multiple chimney constructions discharging up to 260°C hot fluids. A large area of diffuse, low- temperature venting occurs in the area surrounding the high-temperature field. Here, partly microbial mediated iron-oxide-hydroxide deposits are abundant. The hydrothermal vent sites do not show any high abundance of specialized hydrothermal vent fauna. Single groups (i.e. Porifera and Mollusca) have a few representatives but groups otherwise common in hydrothermal vent areas (e.g. vestimentifera, Alvinellid worms, mussels, clams, galathaeid and brachyuran crabs) are absent. Up until now slightly more than 200 species have been identified from the vent area. The macrofauna found in the vent area is, with few exceptions, an assortment of bathyal species known in the area. One endemic, yet undescribed, species of mollusc has been found so far, an gastropod related to Alvania incognita Warén, 1996 and A. angularis Warén, 1996 (Rissoidae), two species originally described from pieces of sunken wood north and south of Iceland. It is by far the most numerous mollusc species at the vents and was found on smokers, in the bacterial mats, and on the ferric deposits. A single specimen of an undescribed tanaidacean has also ben found. The crinoid Heliometra glacialis is dominating large areas surrounding the vent fields. Calcareous sponges were common in the area. Calcareous sponges normally represent only a minor fraction of the sponge fauna and it was therefore a big surprise that eight out of a total of 13 species reported here are calcareans. Annelids were the most speciose group with more than 80 identified species, followed by crustaceans. Possible explanations for the lack of typical vent fauna is discussed.
DE: 0410 Biodiversity
DE: 0450 Hydrothermal systems (1034, 3017, 3616, 4832, 8135, 8424)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting