Structure and photosynthetic response to abrupt thermal stress of a periphyton algal community colonized in a power plant discharge canal.

Tremendous increases in energy needs have led to construction of many new power plants. Effects of heated power plant effluents on aquatic organisms have not been clearly established, Periphyton community structure was used to assess these effects. Species diversity (H") was used to monitor changes in periphyton algal community structure in the discharge canal of a fossil fuel power plant near Waco, Texas. Diversity decreased closer to the power plant discharge. Minimum diversity was 0,96 in June at the sampling station closest the power plant and maximum diversity was 2.89 at the station farthest from the discharge in March. Diatoms dominated the attached algal flora at all stations in the January and March samples. By May diatoms were being replaced by bluegreens at the sampling station closest the power plant, yet diatoms were still the major group at all stations. By June bluegreens were dominant at the station closest the power plant and were increasing at the other' stations but were not dominant. Primary periphyton production per unit biomass was measured following exposure to abrupt thermal change as encountered during shutdown and startup of a power plant. Production was greatest for samples colonized near the power plant discharge for both 10 C and 30 C experimental temperatures. Maximum primary periphyton production using methods was 0.61 ug C organic matter * hr“*.