The effects of power plant passage on zooplankton mortalities: Eight years of study at the Donald C. Cook nuclear plant

Abstract

Zooplankton mortalities resulting from passage through the Donald C. Cook Nuclear Plant (southeastern Lake Michigan) were studied over an 8-year (1975-1982) period. The power plant operated at a low AT (< 12°C) and discharge water temperatures did not exceed 35°C (except September 1978). While zooplankton mortalities were significantly greater in discharge than intake waters, differences were small, averaging < 3%. There was no evidence of additional delayed effects on zooplankton mortality following plant passage. Calanoid copepods (Diaptomus spp, Eurytemora affinis and Limnocalanus macrurus) were most sensitive to plant passage, cyclopoid copepods least sensitive, while cladocerans (Daphnia spp, Eubosmina coregoni) were intermediate in sensitivity. There was no relationship between zooplankton mortalities and temperature (AT, discharge water temperature), suggesting that thermal stresses were not the major source of mortality. The single exception was September 1978 when discharge water temperatures exceeded 35°C and there were large differences between intake and discharge water zooplankton mortalities (net mortality differences of 14-22% for the two units). Mechanical stresses appeared to be the major cause of zooplankton mortality. However, there was only a weak relationship between mortality as a result of plant passage and zooplankton size. Based on our long-term preoperational (1970-1974) and operational (1975-1982) ecological studies in the vicinity of the power plant, we hypothesize that fish predation, rather than power plant operation, probably was the major source of zooplankton mortality in inshore waters during much of the year.

Zooplankton communities of inter-connected sections of lower River Oder (NW Poland)

“…Such a strong reduction was most probably a result of the presence of feeding fry. Evans et al [40] report that in the post-cooling water discharge area the fry are intensely feeding on zooplankton, which is one of the main reasons for its elimination. In general the tributaries have small effect on zooplankton communities in the main channel.…”

Spatial and temporal distribution of fish egg communities in the adjacent waters of Daya Bay nuclear power plant and their relationship with environmental factors

“…Areas S6-S7-S8-S9-S10-S11 (temperature rise 1-3 °C) and S14-S15-S16-S17 (temperature rise< 1 °C) showed dense distribution areas of fish eggs, with average abundance up to 6,806.90 ind./1,000 m 3 and 22,720.74 ind./1,000 m 3 , respectively. The effect of thermal discharge on fish is a complex process, and different fish species have different abilities to adapt to and perceive temperature differences, but generally fishes prefer a slightly higher temperature for spawning than their usual environment (Evans et al, 1986;Lin and Zhan, 2000;Jiang et al, 2016). The temperature rise frontal area of thermal discharge is a mixed area of cold and warm water, where plankton is more abundant.…”