9317739 Michaels The symbiont-bearing planktonic sarcodines (Acantharia, Radiolaria and Foraminifera) are one of the most conspicuous groups of micro- /macrozooplankton in the surface waters of oceanic communities. They are also one of the least studied for their importance in energy flow, nutrient cycles and vertical fluxes in these environments. Planktonic sarcodines play an important role in the production of organic material by organisms >70 um in oceanic plankton communities (via their intracellular symbiotic algae). Moreover, by virtue of their large size (and consequently their potentially rapid sinking rates) they also play a greater role in the flux of material out of the mixed layer than would be predicted by their overall contribution to planktonic biomass. Previous studies indicate great variability in the surface productivity and flux of sarcodine material out of the mixed layer that may be related to the reproductive periodicities of some species of symbiont-bearing planktonic sarcodines or to episodic events leading to rapid population growth. This project will test this hypothesis, and determine the extent to which these periodicities control the temporal changes in the importance of planktonic sarcodines to primary production in the surface waters of the oligotrophic Atlantic Ocean near Bermuda, and to their flux out of the surface waters at this site. *** The symbiont-bearing planktonic sarcodines (Acantharia, Radiolaria and Foraminifera) are one of the most conspicuous groups of micro- /macrozooplankton in the surface waters of oceanic communities. They are also one of the least studied for their importance in energy flow, nutrient cycles and vertical fluxes in these environments. Planktonic sarcodines play an important role in the production of organic material by organisms >70 um in oceanic plankton communities (via their intracellular symbiotic algae). Moreover, by virtue of their large size (and consequently their po tentially rapid sinking rates) they also play a greater role in the flux of material out of the mixed layer than would be predicted by their overall contribution to planktonic biomass. Previous studies indicate great variability in the surface productivity and flux of sarcodine material out of the mixed layer that may be related to the reproductive periodicities of some species of symbiont-bearing planktonic sarcodines or to episodic events leading to rapid population growth. This project will test this hypothesis, and determine the extent to which these periodicities control the temporal changes in the importance of planktonic sarcodines to primary production in the surface waters of the oligotrophic Atlantic Ocean near Bermuda, and to their flux out of the surface waters at this site. ***
