Sieracki, M. E.. Bigelow Laboratory for Ocean Sciences,
Gifford, D. E.. Graduate School of Oceanography, University of Rhode Island,
Thier, E. Bigelow Laboratory,

As part of the U.S. GLOBEC Northwest Atlantic program we measured the prey organisms for early life stages of Calanus finmarchicus in conjunction with grazing rate experiments on Georges Bank - a rich, productive region with high diversity and biomass of nano- and microzooplankton. The contribution of these organisms to copepod diets is poorly known. We report here the results of microscope analyses of heterotrophic and phototrophic nanoplankton (HNAN and PNAN, defined here as 5 - 20 um cells), and microzooplankton from three regions on Georges Bank (bank crest, northeast peak, and southern flank) between January and June 1995. Phototrophic and heterotrophic biomass increased with the progression of the spring bloom. High phytoplankton (chlorophyll and nanophytoplankton) occurred heterogeneously in time and space around the bank, as opposed to a general, bank-wide bloom. Heterotrophic biomass averaged 42% of the total nanoplankton biomass, ranging from 10% (during a Phaeocystis bloom) to 60%. PNAN biomass ranged from 8 to 50 ugC/L, except for a peak of 117 in a Phaeocystis bloom on the bank crest in March. Heterotrophic nanoplankton biomass ranged from 5 to 32 ugC/L. Nano- and microzooplankton form a significant portion of the diets of copepodite stages of Calanus on Georges Bank.
Day: Wednesday, Feb. 3
Time: 11:00 - 11:15am
Location: Hilton of Santa Fe
Code: CS60WE1100H