The Surry Power Station discharges cooling water into the transition zone of the James River. Phytoplankton, zooplankton, benthos, and fouling organism communities were sampled during the years 1969 through 1978, which encompassed a preoperational and an operational period. Temporal changes in the biotic communities followed seasonal patterns of temperature and salinity in the study area, and reflected inherent reproductive patterns of the organisms. Spatial patterns reflected the transport of

more »

... rganisms from the river in the vicinity of the intake to the zone encompassed by the discharge plume, as well as periodic bursts of meroplankton generation in the cooling water canals. Selective destruction of entrained phytoflagellates was observed when discharge water temperatures exceeded 30°C, however these temperatures occurred during periods of maximum primary productivity and maximum flagellate population densities in the river. Zooplankton entrainmentmortalities of up to 12% were observed during a special study in 1975. No impact of the thermal discharge on the biota outside the immediate plume area was detected.