HR: 16:15h
AN: V44A-02    [Abstracts]
TI: Shrimp Populations on Northwest Rota, an Active Volcano of the Mariana Volcanic Arc
AU: * Tunnicliffe, V
EM: verenat@uvic.ca
AF: Department of Biology, University of Victoria, P.O. Box 3020, Victoria, BC V8W 3N5 Canada
AU: Juniper, S K
EM: juniper.kim@uqam.ca
AF: GEOTOP Research Centre, Universit\'{e} du Qu\'{e}bec \'{a} Montr\`{e}al, P.O. Box 8888, Montreal, QC H3C 3P8 Canada
AU: Lim\'{e}n, H
EM: juniper.kim@uqam.ca
AF: GEOTOP Research Centre, Universit\'{e} du Qu\'{e}bec \'{a} Montr\`{e}al, P.O. Box 8888, Montreal, QC H3C 3P8 Canada
AU: Jones, W J
EM: jones@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039-9644 United States
AU: Vrijenhoek, R
EM: vrijen@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039-9644 United States
AU: Webber, R
EM: RickW@tepapa.govt.nz
AF: Museum of New Zealand Te Papa Tongarewa, P.O. Box 467, Wellington, none New Zealand
AU: Eerkes-Medrano, D
EM: dafnef@uvic.ca
AF: Department of Biology, University of Victoria, P.O. Box 3020, Victoria, BC V8W 3N5 Canada
AB: NW Rota-1 is a submarine volcano that manifested active volcanic and hydrothermal activity during submersible surveys in March 2004 (see Embley et al.). Substratum on the volcano summit (520 m depth) was entirely basalt outcrop or variously-sized ejecta lying near the angle of repose. While no fauna inhabited the rim of the volcanic pit, patches of shrimp were located within 25 m and on the nearby summit. Two species are present. {\it Opaepele cf. loihi} shows few morphological differences from either a nearby population on Eifuku Volcano (see Chadwick et al.) at 1700 m depth or from the type locality in Hawaii. A molecular comparison of COI sequences of 13 specimens found little difference from two Hawaiian sequences. Video observations detail frequent feeding activity using spatulate chelipeds to trim microbial filaments as the cephalothorax sways across the substratum. The second species is an undescribed {\it Alvinocaris}. Juveniles of this species appear to form clusters distinct from {\it Opaepele} where they also graze on filaments. Sparse adults of {\it Alvinocaris} range up to 5.5 cm long and display aggressive behaviour moving through patches of smaller shrimp. Densities of {\it Opaepele} were highest on sloping rock walls (over 500 per sq.m.) whereas adult {\it Alvinocaris} were more abundant on rubble. This division may reflect food preference: microbial filaments versus polychaetes and meiofauna. Characterization of particulates from these substrata was conducted using visual sorting and stable isotope composition. As {\it Alvinocaris} matures, the chelipeds enlarge, enabling a greater predatory capacity. Measurements of {\it Opaepele} from digital in situ images reveal a population structure suggesting a recent recruitment. Average size is significantly smaller than the Eifuku population and no egg-bearing females were collected. The disjunct range of this species where it occurs on active volcanoes 6000 km apart is puzzling. Further work on intermediate sites and into the reproductive strategy of the species is required.
DE: 1234 Regional and global gravity anomalies and Earth structure
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting