BLUE GREEN ALGAE (BGA) AND HABS IN THE FINGER LAKES, NY, USA

Blue green algae (BGA) and harmful algal blooms (HABs, BGA with toxins) have negatively affected many lakes in the United States. The Finger Lakes (FL) in New York are no exception. Up to five lakes have experienced HABs with mycrocystin concentrations up to 1,000x’s larger than drinking water standards, and toxins have been detected in some public drinking water supplies. Here, we present a decade of monthly, offshore, mid-lake, limnological data from the eight eastern FLs, daily data from an YSI/Xylem water quality and meteorological buoy, and nearshore limnological data from Owasco Lake collected in 2017 to investigate potential triggers for the onset of HAB blooms.

The eight eastern Finger Lakes have been routinely monitored at a minimum of two, deep water, mid-lake sites during the summer field season since 2005. Six nearshore sites were also sampled each week in Owasco Lake during 2017. Monthly temperature, conductivity, DO, pH, turbidity and fluorescence profile by CTD (SeaBird SBE-25), algal groups by bbe Fluoroprobe, a Secchi depth, a vertical plankton tow (80 um), and surface and bottom water samples for TP, SRP, NO3, TSS and Chl-a analyses were collected at each site. Water samples were analyzed following standard techniques. WQ monitoring buoys (YSI/Xylem) collected daily temperature, conductivity, DO, turbidity, total and pycocyanin fluorescence profiles, and hourly meteorological data.

Shallower Secchi depths, and larger nutrient, suspended sediment and chlorophyll-a concentrations reflecting declining water quality in 2011, in 2014/2015 & in 2017, coincided with the onset of HABs in six of the eleven FLs, and BGA blooms in the remaining five FLs. It suggests that regional nutrient loading issues due to exceptionally heavy spring rains fertilized the onset of BGA blooms. Drone photography indicate that these blooms typically hug the shoreline. Many of the nearshore blooms in Owasco and Seneca Lakes occurred after summer solstice, maximum air and water temperatures and rainfall events, but typically waited until calm or near calm and sunny conditions after a small decline in surface temperatures (water mixing event) to bloom. It suggest that nearshore nutrient sources, e.g., spring rains, macrophytes, BGA, sediment organic matter, zebra mussels and/or Asian clams stimulate BGA blooms in these lakes.