Algae as ecological indicators of water quality

Mohammad I. Abdel-Hamid

Summary

Biological monitoring of environmental health is built on the fact that the decline in quality is usually reflected by alteration in composition and function of the resident biological communities. The aquatic biological communities are assemblages of population structured by biotic interactions and by physical and chemical constraints of their environment. Therefore, the integrated response of the populations to environmental stress will be reflected by alteration in structure and dynamics of the stressed community. Being the principal aquatic primary producers; algae deserve ultimate significance to the function and stability of ecosystem. Planktonic algae are useful for biological monitoring of water quality as they respond to changes in environmental conditions. Periphytic algae serve as micro-loggers for ecological disturbances. Algal bioassays have been extensively used for water quality monitoring. The lecture will highlight the outcome of 25 years field and laboratory researches devoted to reveal the significance algae as reliable indicators of water quality of the River Nile in Egypt. Relevance of qualitative and quantitative analyses of algal communities for the biological characterization of water quality with special emphasis on season effect will be a focal point of concern. Water quality characterization using field and laboratory bioassays with free algal cultures and immobilized algal biosensors will also be addressed. After 25 years of field and laboratory research, it became evident that lessons instructed by the ecosystem are numerous and diverse. The acquired information and knowledge are substantial. The outcomes of field practices are usually overwhelming. Relatively few findings were fairly understood and went smoothly within the borders of expectations. Others went to the opposite direction with no match, even, to the bottom of any prediction. The bulk of data maintain an intermediate position. As time proceeds in parallel with the continuity of learning and research, only the keen students may be able to understand how to reveal the mystery of some ecological data they have collected earlier. Nevertheless, some ecological observations may remain totally or partially unresolved. This indicates the complexity of ecosystems and the necessity of the ecological research. 

Key Words: The River Nile, Algae, Water quality, Biomonitoring, Ecotoxicology