Research Technical Report

The Biogeography and Distribution of Megafauna at Three California Seamounts

Lundsten, L. (Decemeber 2007)

Master of Science Thesis,
Moss Landing Marine Laboratories,
California State University Monterey Bay

ABSTRACT

Video recordings from Remotely Operated Vehicle (ROV) dives are used to describe the biogeography and distribution of megafauna communities found at three seamounts off central and southern California, USA. In total, 27 ROV dives were annotated in detail using the Monterey Bay Aquarium Research Institute's (MBARI) Video Annotation Reference System (VARS). Video analysis yielded 136,716 biological observations. In all, 236 megafauna taxa are described from observations at these seamounts. Seamount bathymetry was analyzed to relate the observed faunal distribution to seamount slope, aspect, and bathymetric position index. Video transects, collected at Davidson Seamount in 2006 and at Pioneer Seamount in 2007, were analyzed to quantify species' densities. Thirteen new species including sponges, corals, and echinoderms were observed and collected as part of this research; most of these are being or have been described by taxonomists. This study shows there is little or no endemism among invertebrate megafauna and demersal fishes identified at these seamounts. Results also indicate that many seamount organisms have specific depth distributions, and because of this, the depth of the seamount influences community composition. Additionally, proximity to the continental slope and seamount shape are important in determining community structure and organism distribution.