Steinberg¹, Deborah K., Laurence P. Madin², Astrid Schnetzer³

¹Virginia Institute of Marine Science, P.O. Box 1346, Gloucester Pt., VA, 23062, USA, Tel: 804-684-7838, Fax: 804-684-7293, E-mail: debbies@vims.edu, ²Woods Hole Oceanographic Institution, Biology Dept., Woods Hole, MA, 02543, USA and ³University of Southern California, Department of Biological Sciences, 3616 Trousdale Parkway, AHF 301, Los Angeles, CA 90089, USA

Zooplankton community structure and biogeochemical cycling at the Bermuda Atlantic Time-series Study (BATS)

One significant contribution of the JGOFS program is an increase in our understanding of how zooplankton affect biogeochemical cycling in the worlds’ oceans. This includes investigations of how zooplankton communities vary with time and the fundamental role zooplankton play in the biological pump. Here we synthesize results from zooplankton biomass and species composition time series at the U.S. JGOFS Bermuda Atlantic Time-series Study (BATS) in the Sargasso Sea along with process studies examining the role of zooplankton in transport of carbon and nutrients to depth. The time series show marked diel, seasonal and interannual changes in both total biomass and taxonomic composition. These temporal patterns will be discussed in the context of physical and other biological data collected at BATS. Zooplankton play an integral role in the flux of material out of the euphotic zone and in nutrient cycling at BATS via active transport by vertical migrators and by production of sinking fecal pellets. Migrating zooplankton actively transport a substantial amount of dissolved inorganic and organic C and N to deep water (via respiration and excretion), and may contribute to non-Redfield remineralization patterns seen at depth. Taxonomic changes in the zooplankton community in the Sargasso Sea can also dramatically affect the composition and sedimentation rate of fecal pellets, and thus the export of organic material. Comparisons to JGOFS studies in other ocean basins show interesting differences in flux contributions attributable to zooplankton, relative to primary production or export measurements from sediment traps.