EFFECTS OF CHANGES IN SEWAGE POLLUTION ON SOFT-BOTTOM MACROFAUNA COMMUNITIES IN THE INNER OSLOFJORD, NORWAY

The macrobenthic fauna of Vestfjorden, inner Oslofjord was sampled in 1980 and 1985 at 19 stations. The aim of this study was to detect possible faunal changes following the start of a sewage treatment plant in 1982. The faunal data were analyzed by a variety of methods including diversity indices, log-normal distribution of individuals among species and classification and ordination analysis. The results show a decline in species number and abundance which may be related to increased pollution. However, the diversity and the evenness have increased. The area within a radius of 2–3 km from the outlet of the treatment plant shows clear pollution effects white the marginal areas show improved conditions. © 1990 Taylor & Francis Group, LLC.