Distribution of Cyanobacteria and Microcystin in Lakes of the US Driven by Combination of Lake, Watershed, and Climate Characteristics
Citation:
Handler, A., J. Compton, M. Dumelle, M. Weber, R. Hill, L. Jansen, M. Brehob, R. Sabo, AND M. Pennino. Distribution of Cyanobacteria and Microcystin in Lakes of the US Driven by Combination of Lake, Watershed, and Climate Characteristics. 2024 Oregon Cyanobacterial Harmful Algae Bloom Meeting, Corvallis, OR, March 08, 2024.
Impact/Purpose:
Harmful cyanobacterial blooms can produce toxins which impair freshwater ecosystems used for drinking water, recreation, and habitat for aquatic biota. With increased awareness and reporting of cyanobacteria blooms, water managers need information about how to prioritize monitoring locations in surface waters that may be affected. This presentation highlights analyses that combine data from the National Lakes Assessments field assessments and a variety of watershed, climate, and lake characteristic to model the risk of toxic blooms in lakes across the US. This presentation will be to an audience at the Oregon Lakes Association CyanoHAB Stakeholder Meeting which is attended by research scientists and well as practitioners and managers for Oregon and the Pacific Region's aquatic resources.
Description:
With increasing concerns about freshwater cyanobacteria blooms, there is a need to identify which waterbodies are at risk for developing these blooms, especially those that produce cyanotoxins. To address this concern, we developed spatial statistical models using the US National Lakes Assessment, a survey with over 3500 spring and summer observations of cyanobacteria abundance and cyanotoxin concentration in lakes across the conterminous US. We combined these observations with other nationally available data to model which lake, watershed, and climate factors best explain the presence of harmful cyanobacterial blooms. We found that both cyanobacteria abundance and probability of microcystin detection was associated with higher total nitrogen concentrations, pH, shallower depths, higher lake evaporation relative to inflow, and greater watershed agricultural land cover. Additionally, cyanobacteria abundance was positively related to air temperature and negatively related to precipitation. In contrast, the probability of detecting microcystin was unrelated to climate but higher in lakes with longer fetch and lower baseflow water inputs. Both models had spatial covariance, indicating there are similarities in lakes that are closer in space beyond that captured by the covariates in the models. These models can help identify which lakes are more vulnerable to harmful cyanobacteria blooms and can help estimate the risk of blooms in locations that lack cyanobacteria or toxin data.