BEST: A novel molecular approach to measuring In situ feeding rates of copepods in the South Eastern Bering Sea.

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Durbin 0909415University of Rhode islandMesozooplankton play a critical role in determining carbon flow from primary producers to higher trophic levels. In the SE Bering Sea interannual changes in the timing and extent of both sea ice cover and summer stratification will affect their role in determining the path of carbon flow, whether through the pelagic ecosystem or to the benthos. Knowledge of the actual in situ mesozooplankton diet composition and ingestion rates is essential to understanding the flow of carbon in this system. Information about these rates using traditional bottle incubation techniques will be compromised because of the strong vertical gradients in the mesozooplankton prey environment making sampling the appropriate prey field difficult. The PIs propose a field investigation of in situ feeding rates by copepods on the SE Bering shelf during spring and summer using a novel molecular technique they have developed to quantitatively measure ingestion rates on different prey species from stomach content analysis. They will use the 18S ribosomal RNA gene as a marker to identify different prey species present in the guts of copepods and quantitative real-time polymerase chain reaction (q-PCR) to measure copy number of this gene for each prey species. Ingestion rates will be calculated from this gut content information, 18S copy number/organism, and DNA digestion rates. By combining these in situ ingestion rate measurements with zooplankton abundance measurements and the prey field composition, they will be able to determine the fate of phytoplankton production under the varying environmental conditions. Ultimately, they plan to use these in situ consumption estimates to evaluate the role of copepods in carbon flow in the Bering shelf ecosystem.