TROPHIC PROFILING OF LAKE ONTARIO AT THE MOUTH OF THE GENESEE RIVER IN THE SUMMERS OF 2016, 2017, AND 2018 AND ITS CORRELATION WITH ALGAE BLOOMS AND WEATHER CONDITIONS

Each summer, massive algal blooms in the Great Lakes region lead to eutrophication, which disrupts aquatic life, decreases the recreational value of the lakes, and threatens drinking water supplies of shoreline communities. In this study we characterized the trophic profile of Lake Ontario at the mouth of the Genesee River in Monroe County, NY for three consecutive summers, evaluated the contribution of the lower watershed of the Genesee River in the eutrophication of the lake, and correlated the trophic profile with air temperature, lake water level, and total rainfall from January to June. At a beach adjacent to the mouth of the river, large algal blooms were present. Samples from sites along the river and the surrounding lakeshore were analyzed for a variety of parameters including total phosphorus (TP), nitrate, ammonium, and dissolved oxygen (DO). A qualitative assessment of the algae blooms was also carried out. During the summer months, a bulldozer pushes algae away from the swimming area and into a “restricted area” next to the pier. In 2016 and 2018, this algae-rich area was found to be hypereutrophic and had TP levels many times higher than the EPA limit of 0.2 mg/L and ammonium levels higher than the EPA limit of 2 mg/L; in consequence, the DO levels were lower than the dead zone threshold of 5 mg/L. As for nitrate-nitrogen measurements, the levels were higher than the clean water guideline of 1 mg/L, but within the EPA limit of 10 mg/L in most locations. The data indicate that the TP levels were of much greater concern than the nitrogen levels at all sites. Genesee River samples also showed high TP, suggesting that the river contributes significantly to increasing the total phosphorus index of the lake. The lower trophic profile in 2017 as compared to 2016 and 2018 can be explained by the variation in the rainfall and lake water level; 2017 had much higher than average rainfall and lake water level, which explains the lower trophic index as a consequence of major dilution. TP shows a strong negative correlation with the total amount of rainfall (-0.996) and the lake water level (-0.982), while not affected by temperature (0.120). Current experiments are being conducted to target nutrient pollution and find a solution for the remediation of excess nutrients in the Genesee River-Lake Ontario area, as well as the Great Lakes region as a whole.