MICROZOOPLANKTON-ABUNDANCE, BIOMASS, CONTRIBUTION TO CHLOROPHYLL AND GRAZING IN THE EASTERN BERING SEA IN SUMMER
Microzooplankton composition, biomass and grazing impact were determined for summers 2008-2010 (cold years). During summer stratification on the middle shelf, microzooplankton biomass was often higher than calculated phytoplankton biomass and microzooplankton grazing exceeded phytoplankton daily growth. Mixotrophic ciliates contributed substantially to mixed layer chlorophyll. A deep chlorophyll maximum was prevalent on the northern middle shelf; grazing coefficients were similar, but because of the higher phytoplankton biomass, estimated microzooplankton ingestion and secondary production were higher than in the corresponding mixed layer. Microzooplankton biomass was lower in less stratified waters near the shelf break, greenbelt, and around the Pribilof Islands. Microzooplankton consumed 67-78 percent of estimated phytoplankton daily growth in the mixed layer in off and outer shelf regions. Regional estimates of microzooplankton ingestion of phytoplankton carbon were 4.4 -11.0 micrograms carbon/liter/day, with highest ingestion in off and outer shelf and Alaska Peninsula regions with lower ingestion in middle and inner shelf regions. Region, extent of summer stratification, presence of localized blooms, and mixotrophy all have major influences on coupling of microzooplankton to phytoplankton in the eastern Bering Sea in summer.
Stoecker, D. K., UMCES, Horn Point Laboratory, USA, firstname.lastname@example.org
Weigel, A., UMCES, Horn Point Laboratory, USA
Lomas, M., Bigelow Laboratory for Ocean Sciences, USA, email@example.com
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