Meeting Abstract

P3.141  Tuesday, Jan. 6  Pycnogonid-cnidarian interactions in the deep Monterey Submarine Canyon BRABY, C.E.; PEARSE, V.B.*; VRIJENHOEK, R.C.; BAIN, B.A.; Monterey Bay Aquarium Research Institute, Moss Landing, CA; University of California, Santa Cruz; Monterey Bay Aquarium Research Institute, Moss Landing, CA; Southern Utah University, Cedar City vpearse@ucsc.edu

Whale carcasses, sunken wood, and cold seeps provide organically enriched oases in the food-limited deep-sea benthos. At 3 such enriched habitats in Monterey Bay, California, at a depth of nearly 3,000 m, we observed pycnogonids (sea spiders) of at least two species, Colossendeis gigas and C. japonica, feeding on sea anemones commonly found there. Submersible remotely operated vehicles (ROVs) provided direct observations of feeding, as well as high definition video and photographic images. We recorded the presence and abundance of both pycnogonids and anemones over the course of 12 visits during 2002-2006. The sedentary anemone Anthosactis pearseae attached directly to whalebones whereas the pom-pom anemone, Liponema brevicornis, was found resting on soft sediment, rolling in benthic currents, or amassed where these currents were disrupted by topography, as at whale-falls, wood-falls, and clam fields. Both pycnogonids and anemones were abundant during 10 of the 12 dives. The whale-fall community appears to provide especially plentiful prey for the anemones, during stages when the decaying carcass attracts enormous numbers of scavenging amphipods. Like the pom-pom anemones, large pycnogonids were dramatically more abundant at these oases than in the surrounding benthos. This predator-prey pair potentially disperses together, and pycnogonids are a plausible selective force in the evolution of tentacle autotomy by pom-pom anemones. Networks of such interactions at these deep benthic oases define them as established, though short-lived, ecological communities, not merely accidental assemblages.