Benthic Faunal Dynamics during Succession Following Pollution Abatement in a Swedish Estuary

Abstract

took about eight years. By then the composition of the community was similar to that recorded forty years earlier. The successional changes in number of species, individuals and biomass are illustrated for the total fauna as well as for dominating groups. The sequential changes of some numerically dominant populations showed a bell-shaped curve pattern. During the first years after pollution abatement, when polychaetes dominated, these population changes were drastic but evened out in later seral stages. The role of larval recruitment in succession is discussed. Three diversity indices were used to assess the community structure: Shannon's formula, its measurement of evenness, and Sanders' rarefaction technique. As tools for assessing pollution or recovery, the two former had to be used with care, as the highest values were recorded at the beginning of the recovery process when the individuals found were few but evenly distributed among the few species present. The rarefaction technique and the measure of species richness were more satisfactory for this kind of assessment.