Diatoms as indicators of long-term nutrient enrichment in metal-contaminated urban lakes from Sudbury, Ontario.
from Sudbury. Diatom assemblages were primarily dominated by oligotrophic taxa prior to watershed development; however, with the onset of urban environmental stressors (e.g., septic systems, the application of lawn fertilizers and watershed development), there was a shift toward taxa that thrive in more productive systems. Diatom assemblages also seem to track an increase in lakewater pH through time, which is likely related to increased acid neutralizing capacity as a result of watershed disturbances, algal assimilation and bacterial reduction of NO−3 , and increased base cation export from the watershed due to acidic deposition. Insight into predisturbance conditions of the lakes should help lake managers set realistic biological targets for restoration and may be used to help gauge the response of these systems to future mitigation efforts.