Alpha and PBm as Functional Indicators of Aquatic Ecosystems

Abstract

The effect of PCB ' s , DDT, phosphorus and zooplankton density on the photosynthetic parameters Alpha and PBm was investigated . If these parameters prove reliable as functional indicators , their use may simplify the process of monitoring aquatic ecosystems. Unialgal cultures were used in experiments which involved the use of radioactive carbon labeling and an artificial light incubator . Alpha and PBm increased in response to the addition of phosphorus in Anabaena flos-aquae cultures deficient in this nutrient and to increasing densities of Daphnia pulex in cultures of Chlorella vulgaris. DDT had a stimulatory effect on Alpha but not on PBm in Anabaena flos-aquae while PCB's had no effect on either parameter. Chlorophyll concentration in the incubator bottle negatively affected Alpha probably through self shading .