C. polykrikoides ranges from
10 to 40 mm in size and dominates the >20 mm phytoplankton
community during bloom conditions (>90% of biomass; Gobler
et al., 2012; Kudela and Gobler, 2012, this study) thus the 20 mm
filters from bloom samples were used to infer tracer uptake by C. polykrikoides. At the beginning and end of the incubation, a small
aliquot of each bottle (250 mL) was removed to determine total
activity (the amount of isotope added). The 57Co samples were
analyzed on a LKB Wallac 1282 COMPUGAMMA CS universal
gamma counter and the 14C and 3H samples were analyzed on a
scintillation counter (Packard-Canberra Co. PR1-Carb2100TR).
Uptake (r) of vitamins B1 and B12 were calculated by using the
equation: