Assessing anthropogenic impact on boreal lakes with historical fish species distribution data and hydrogeochemical modeling.
Bottom Line: Quantifying the effects of human activity on the natural environment is dependent on credible estimates of reference conditions to define the state of the environment before the onset of adverse human impacts.In 2010, MAGIC predicted chemical recovery in 50% of the lakes, however roach only recolonized in five lakes after 1990, showing a lag between chemical and biological recovery.Based on our results, we show how the conceptual model can be used to understand and prioritize management of physico-chemical and ecological effects of anthropogenic stressors on surface water quality.
Affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, Uppsala, SE-750 07, Sweden.Show MeSH
Mentions: In the regional MAGIC application presented here, no attempt was made to calibrate in-lake Ali concentrations. Long-term (1997–2011), measured Ali values were only available for two lakes in the study set. The highest measured Ali in Övre Skärsjön and Rotehogstjärnen were found in 2001, with 51 and 69 μg L−1, respectively (Fig. 6). Övre Skärsjön exceeded the critical limit of 50 μg L−1 once since 1997, whereas Rotehogstjärnen exceeded the limit multiple times. To further elaborate the specific effects of Al speciation on biota, the MAGIC model needs to be calibrated toward a large dataset. In our application of the MAGIC model, given the assumptions made for Ali, ten of the 85 lakes predicted Ali > 1 μg L−1. Three lakes predicted Ali > 50 μg L−1. MAGIC predicted Ali to 90 μg L−1 between 1980 and 1990 for Övre Skärsjön (Fig. 6a). The modeled Ali for Rotehogstjärnen does not exceed 50 μg L−1 during 1980–1990 (Fig. 6b). The critical Ali level for roach (50 μg L−1) does not occur when pH is above 4.8 (Fig.5).
Affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Box 7050, Uppsala, SE-750 07, Sweden.