Lunch Seminar "Effect of liming on benthic fauna in Västernorrland county. ”

Lunch Seminar "Effect of liming on benthic fauna in Västernorrland county. ”

Abstract

In this study, still being in the analysing phase, the effect of liming on benthic fauna was investigated. The dataset consisted of results from different environmental monitoring programmes in the county of Västernorrland. This county is not and has not been as afflicted by acid fallout as southern parts of Sweden, and the liming started later than in other parts of Sweden. Yet the liming shows significant results in this county.

pH has remain unchanged in the treated waters, but decreased in the untreated ones. Alkalinity has decreased in running waters, but more in the untreated ones. The alkalinity in lakes has been more or less unchanged during the study period. Water colour has increased in all waters, but more in the untreated ones.

In treated waters the species composition seemed to be unchanged over time, whereas it changed in the untreated waters.

The datasets also included results from surveys for the freshwater pearl mussel (Margaritifera margaritifera). The results show that the mussel thrives in clear water with pH close to 7.0. This pH is far from the pH targets for the liming programmes in Sweden (5.6 or 6.0). Thus the liming programmes as they are conducted today may not facilitate the recovery of the species in most parts of Sweden.