Chironomid Autoecology of the Past and Present, and a Causal Analysis of Recreational Shoreline Developments on Hypolimnetic Oxygen in Algonquin Park Lakes

Recreational cottages continue to be leased within Algonquin Park despite inadequate assessments of cottage impacts on lake water quality and ecosystem integrity. Cottages can increase phosphorus export to lakes, resulting in increased productivity and declines in hypolimnetic oxygen. Algonquin Park lakes contain dense populations of lake trout (Salvelinus namaycush) and brook trout (Salvelinus fontinalis), which are sensitive to declining hypolimnetic oxygen. Dipteran subfossil remains were used to calibrate a VWHO inference model (RMSEP = 1.7 mg O2 L-1) to determine baseline VWHO (historical, pre-European settlement, < ca. 1850 CE) and assess VWHO change since then using a top-bottom paleolimnological approach. Despite increased anthropogenic activity in the park, inferred VWHO did not change predictably since circa 1850. We did not detect a significant effect of cottages on VWHO. However, regional declines in phosphorus export may be responsible for muting the effects of anthropogenic phosphorus inputs on VWHO in Algonquin Park lakes.