Diatom- and Chironomid-Inferred Eutrophication of Bouchie Lake, British Columbia

摘要: Diatom and chironomid analysis of sediments encompassing the past 400 years from Bouchie Lake, British Columbia, suggests two distinct periods limnological conditions. Prior to 1950 AD, Fragilaria construens F. pinnata are most common diatom species, Chironomus, Procladius Tanytarsini dominate record. Moderately low nutrient concentrations consistent with oligo-mesotrophic lakes inferred. From 1950, assemblage is dominated by Stephanodiscus parvus, a eutrophic indicator, whereas communities show relative increase in littoral taxa coincident lower head capsule abundance. Higher levels, specifically total phosphorus, which increased 8 pg L - 1 prior 20 currently, midge indicative oxygen concentrations. Observed biotic changes levels inferred sediment core correspond historical land-use changes.