Harp Lake, Ontario
Harp Lake is an oligotrophic, single basin lake in Ontario, Canada (45º23'N; 79º08'W). The lake covers over 710,000 m2 and has a depth of 37.5 m. Harp Lake does have dimitic stratification and is a temperate lake. Additionally, Harp Lake does not have anaerobic conditions in the water column because it is a relatively deep lake. The water in Harp Lake has a pH of 6.3 (slightly acidic). This pH is caused by the presence of acids and the lack of alkaline bases.[3] Slightly acidic lakes normally have a granite or siliceous bedrock and they are poorly buffered. Also, these lakes commonly have calcium-poor soils or thin soils. It is one of the "Dorset lakes" near Dorset, Ontario, a small community located on the boundary between the Algonquin Highlands Township in Haliburton County, Ontario and Lake of Bays Municipality in Muskoka District, Canada. Ecology Nutrient levels The forested watershed area around Harp Lake is around 4.7 km2 and comprises six streams and shoreline runoff. There has been evidence that the total discharge of these six streams has decreased by 24.9% from 1978-2006. Four different concentrations of cations (Ca, K, Mg and Na) were observed in Harp Lake from 1978-2006. There was found to be a negative trend with the nutrients Ca, K and Mg concentrations while Na was found to increase over time. These two trends were correlated with stream base cation concentration, stream discharge and shoreline load. With each cation stream concentration and discharge were a key player with the trends while shoreline load (road salt) played a key role in the increase of Na. Specifically, Na increased between 250% and 350% as a result of road salt contamination. Not only did Na concentrations increase because of road salt contamination but Cl concentrations also increased. Cl concentrations increased from 0.6 mg*L−1 to 2.7 mg*L−1. While the increased levels of Na and Cl concentrations have caused localized impacts to occur near stream crossing there is a large dilution factor which has caused there to be little impact on the lake ecosystem. The Na and Cl concentrations are predicted to have little to no effect on soft-water organisms even though their tolerance to salt is low. Oxygen levels From 1975 to 1995 research was conducted to measure summer hypolimnetic oxygen levels. The hypolimnetic oxygen levels stayed persistently over 4 mg L−1 . Additionally, in 2010, researchers measured total mercury, methyl mercury, total organic carbon, sediment bulk density, redox potential and percent fines on a sediment core. The sediment core was collected from littoral to profundal depths along transects. Total mercury, total organic carbon, and total mercury:methyl mercury ratio decrease with sediment depth. Geographic features Harp Lake has been studied by the Dorset Environmental Science Centre since the 1970's. The Dorset Environmental Science Centre includes tributary sampling and a meteorological station. The Dorset Environmental Science Centre have found that the drainage from Harp Lake flows into the Muskoka River and then straight into Lake Huron. There has been an increased thermal stability