DEVELOPMENT AND STABILITY OF FISH ASSEMBLAGES AFTER LIME TREATMENT

Long-term effects of limestone treatment on fish populations in acidified lakes in Sweden have been examined since 1983 to assess the development and stability of fish assemblages after lime treatment. In total, 77 lakes were sampled twice using standardized methods between 1983 and 1988. The lakes were limed 1-16 yr before the second sampling. Physical and chemical variables and the fish data were reduced using PCA ordination and the resulting relationships were analyzed using linear regression and ANOVA. Relationships between the fish assemblage characteristics and the environmental factors were highly dependent on the species composition of the assemblages. The number and diversity of fish species were correlated with both the extent of acidification and habitat diversity of the lakes. The importance of species interactions after lime treatment was suggested by a negative relationship between changes in the scores of community along the first component of the fish PCA and changes along two of the other species components between the two samplings. Despite a weak tendency towards reduced variability in species proportions as time passed since the first liming, the development of community stability, expressed as lack of change in species proportions, was insignificant.