1The Effect of a Deep Seamount on Zooplankton Abundance and Diversity

Seamounts are common throughout the Pacific Ocean and may be a source of biological patchiness that is now being exploited by fisheries which trawl for the benthic nekton that live over them. Despite their abundance, their effects on marine ecosystems remain under-researched and poorly understood. This study attempts to characterize the impact one seamount has on the zooplankton communities that surround it. An unnamed seamount in the Eastern Central Pacific was identified with a peak height of 824 m below sea level. 3 sampling sites were chosen: one upstream of the summit, one near the summit, and one downstream of it. At each location, a neuston net was towed on the surface and a meter net was towed through the deep scattering layer. The collected sample was measured for density by calculating its biovolume and 100-counts were done to approximate the composition of the zooplankton community. The density of zooplankton was 3 times higher downstream of the seamount than upstream and over it. The downstream sampling site also had more trophic diversity with higher trophic level organisms present. In conjunction with two other studies, this data indicates that this seamount can be characterized by upwelling that is swept downstream to create subsequent phytoplankton and zooplankton blooms