Harmful Algal Blooms (HABs) on the Horizon: Protecting Lakes in Acadia National Park from the Threat of Harmful Algal Blooms

Fowler, Rachel

Toxin-producing cyanobacteria can form HABs in lakes, leading to unfavorable impacts on drinking water, recreation, tourism, and ecosystem structure and function. Lakes in ANP have excellent water quality, but in the last decade several Maine lakes have experienced unprecedented and costly HABs, as have lakes in other National Park Service (NPS) units. To assess early warning signs in lakes varying in trophic status and other water quality parameters, we sampled Jordan Pond, Seal Cove Pond, and Witch Hole Pond in 2020. We 1) instrumented each lake with temperature and dissolved oxygen sensors for high-resolution data; 2) performed biweekly water column sampling; 3) tracked phycocyanin (an indicator of cyanobacteria) concentration; 4) prepared bathymetric maps of each lake; 5) collected meteorological data; and 6) assessed long-term monitoring data collected by the ANP Air & Water Quality Program. We prepared an assessment of each lake type that evaluated risk conditions including temperature, dissolved oxygen, chlorophyll a (chl a ) and phycocyanin concentration, and nutrient levels. We also considered how the effects of lake morphometry could affect susceptibility to HABs. Shallow, eutrophic lakes like Witch Hole Pond could be more vulnerable to HAB formation due to high surface and water column temperature, low dissolved oxygen, high nutrients, and greater relative concentrations of chl a and phycocyanin. Jordan Pond, a deep oligotrophic lake, did not exhibit early warning signs of HABs, and we expect that similar lakes in ANP are equally resistant to HAB conditions.