Selective Feeding by Zooplankton: Implications for Lake Productivity

摘要

The relationship between phytoplankton, bacteria, and zooplankton activities and distributions was studied in two Indiana lakes: Crooked and Little Crooked. Primary production in the metalimnion was an important source of fixed carbon in these lakes. In Crooked Lake, metalimnetic production accounted for 30-45% of the total production during the summers of 1979-1981. Changes in the vertical distribution of biomass in the water column had a greater effect upon metalimnetic production than differences in water transparency or incident solar radiation. Excretion of organic carbon by phytoplankton populations is a potentially important source of carbon for heterotrophic bacteria. The photosynthetic rates of water samples were proportional to light intensity. Bacterial activity was primarily associated with planktonic bacteria rather than cells attached to particles.