Use of a sensitive indicator species in the assessment of biological effects of sewage disposal in fjords near Bergen,Norway

Coordinated environmental, ecological and biochemical studies have been applied to assess the impact of sewage disposal in a fjordic system near Bergen, Norway. The ecological and biochemical effects were studied in 1983 at four sampling locations situated along a spatial gradient of effects of the sewage on conditions in the sediments. Two of the locations, near Dolviken, were found to be considerably affected by the sewage. Relatively few species of macrobenthic invertebrate fauna were present at these locations, and analysis of the distribution of individuals among species indicated distortion of the benthic community structure. On the basis of its distribution along spatial gradients of organic enrichment and various criteria relating to its suitability for biochemical analysis, the polychaete Glycera alba (Müller) was selected as the most suitable pollution-sensitive indicator species for use in the biochemical studies. In individuals from the two affected locations near Dolviken, maximal activities of the regulatory glycolytic enzyme, phosphofructokinase, and the pyruvate oxidoreductase, alanopine dehydrogenase, were very low. Activities of several other enzymes associated with carbohydrate catabolism were also lower in these groups than in the reference group collected from Raunefjorden. The ecological and biochemical measures both corresponded closely with the changes in environmental conditions along the gradient of sewage effects. The results are discussed with reference to earlier coordinated ecological and biochemical investigations carried out in Scotland and Norway and to experimental studies of the effects of pollutants and hypoxia on energy-yielding metabolism of polychaetes. It is suggested that the enzymatic changes in G. alba may be a sensitive component of an integrated metabolic response, which may involve a decrease in glycolytic energy production for the fuelling of muscular activity. Further development of this coordinated ecological and biochemical approach is discussed, with emphasis on its potential utility in the assessment of biological effects of the disposal of organically rich waste materials in coastal waters.