Use of caged fish for mariculture and environmental monitoring in a power-plant cooling-water system.
Estuarine fishes were cultured in cages in the intake area, at the head of the 9.8-km discharge canal, and at three locations in the 1053-ha cooling lake of a power plant near upper Galveston Bay, Texas, from 1 September 1975 to 11 September 1976 both to explore the feasibility of utilizing the cooling waters for mariculture and to evaluate the ecological effect of the cooling system on wild populations of fishes. Interpretations were based on daily measurements of six hydrological parameters, survival and growth of 13 species of fish within cages, and water and tissue concentrations of heavy metals and pesticides. Major hydrological characteristics of the cooling system were as follows: (1) Temperature in the dishcarge canal averaged 8-9 C higher than those in the intake area, while temperatures at the outfall of the cooling lake averaged only about 2 C higher. (2) Salinity at the surface of the intake area often dropped abruptly following heavy rainfall, while salinity at the bottom of the intake area, in the discharge canal, and in the cooling lake remained more stable. (3) Dissolved oxygen levels and pH generally increased from intake area to discharge canal to cooling lake, which probably indicated in primary production and improvements in overall water quality. (4) Total gas saturation in the discharge canal frequently exceeded 120% during winter.