Carbon flux and recycling associated with zooplanktonic fecal pellets on the shelf of the Middle Atlantic Bight

Abstract

Abstract Sediment traps were deployed for 5 days during March 1988, at 20 and 33 m in 42 m of water over the continental shelf off Norfolk, Virginia (SEEP-II study area). During the sediment trap deployment, a time-series study determined the community and age-structure of copepods as well as the standing stocks, production rates and settling velocities of fecal pellets. Fecal pellets comprised less than 1% of the total particulate carbon collected in the sediment traps and ca 0.3% of particulate carbon found in the water column. Mean fecal pellet production by adult copepods feeding in natural seawater ranged from 1 to 2 pellets animal −1 day −1 , equalling approximately 0.1–0.3 μm C day −1 .Average fecal pellet volume ranged from 4 × 10 5 μ m 3 for pellets produced by Centropages typicus females to 14 × 10 5 μ m 3 , for pellets produced by Calanus funmarchicus females. The pellets produced by C. finmarchicus were important in the downward vertical transport of phytoplankton carbon, while pellets produced by smaller copepods were primarily recycled in the water column. Lateral advective processes altered the species composition of zooplankton at our study site. The onshore and offshore movement of different zooplankton communities with varying size-structure could have a substantial impact on the magnitude of vertical carbon transport on continental shelves.