Benthic invertebrate communities on three seamounts off southern and central California, USA

Abstract

Seamounts are unique and biologically productive deep-sea habitats that have often been described as having high levels of endemism, highly productive fisheries, and benthic commu- nities vulnerable to trawl fishing. We describe the abundance and distribution of benthic megafaunal invertebrates found on 3 seamounts off central and southern California. Video observations were taken during 27 dives of a remotely operated vehicle (ROV) and were annotated in detail using the Monterey Bay Aquarium Research Institute's (MBARI) video annotation reference system (VARS, http://vars.sourceforge.net/). Video analysis yielded 134 477 observations of 202 identified inverte- brate taxa. Video transects were analyzed to quantify organism density. Thirteen new species were observed and collected. Invertebrate communities at Davidson and Pioneer Seamounts were domi- nated by passive suspension-feeding cnidarians (mostly corals), but at Rodriguez Seamount, a guyot, the invertebrate community was dominated by holothurian echinoderms. We found no evidence of endemism among the megafauna at these 3 seamounts, which are all in close proximity to each other and the continental margin.