The general objective of this project is to contribute to the understanding of time-varying biogeochemical fluxes in the oceanic subtropical Pacific by adding a zooplankton sampling component to the Hawaii Ocean Time-series (HOT) Program. The first three years of sediment trap data from this Program have revealed seasonal and interannual patterns in export fluxes that cannot be adequately explained by concurrent variations in primary productivity. Since large zooplankton and micronekton are implicated in the export of organic material from surface waters by virtue of their production of large, rapidly sinking fecal debris and active vertical migrations, we propose to use this opportunity to test the hypothesis that observed seasonal and interannual variability in sediment trap flux are related to patterns in the occurrence of zooplankton. The research program will include: (1) determining the community biomass structure of zooplankton from dry weights, carbon, and nitrogen analyses of size-fractionated net collections; (2) estimating the relative magnitudes of migrating and nonmigrating zooplankton from comparison of day- and night-time catches: (3) assessing relative changes in the role of zooplankton as direct consumers of primary producers from bulk gut fluorescence analyses; and (4) estimating, from microscopical analyses, patterns in the direct contribution of zooplankton fecal material to export flux.
