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Great Lake beach-goer behavior during a retrospectively detected bloom of cyanobacteria
Citation:
Hilborn, E, W. Krueger, R. Stumpf, B. Schaeffer, E. Sams, AND Tim Wade. Great Lake beach-goer behavior during a retrospectively detected bloom of cyanobacteria. International Conference Toxic Cyanobacteria, Wuhan, CHINA, October 22 - 28, 2016.
Impact/Purpose:
Algal blooms are becoming more commonly reported at recreational beaches in the US. The Office of Water is actively working to develop recreational water guidelines for algal bloom toxins to guide beach managers. This report suggests that people do not necessarily avoid bloom exposure during recreational activities.
Description:
Cyanobacteria blooms pose a potential health risk to beachgoers. We conducted a prospective study of weekend beachgoers at a public Great Lake site during July – September 2003. We recorded each person’s health status and activity during their beach visit. We measured: water and air temperature, wind speed and wave height each study day. During the study, no warning of cyanobacteria blooms was issued. We confirmed the presence of blooms retrospectively using MERIS data from the Envisat-1 satellite. During 16 weekend study days, 2,840 people participated in the study. Fifty five percent of all participants were female, and 26% were children. During a retrospective assessment of remotely sensed satellite imagery, a bloom of cyanobacteria was detected during August 16 – 24. The peak bloom period included 4 study days. During the peak bloom, a significantly higher percentage of participating preschool children and young adults, and a lower percentage of adults over 30 years of age reported body contact with water compared to non-peak study days. Staff members sampling water during a peak bloom day reported algae in the water. We measured significantly higher (250 C vs. 230 C, p<0.05) mean water temperature during peak bloom days compared to non-peak study days. Young children and adults were not deterred from water contact during the cyanobacteria bloom. It is not clear if beachgoers were aware of the presence of the bloom. As cyanobacteria bloom occurrence increases in recreational waters, active interventions to discourage water contact during blooms are needed to reduce beachgoer exposure. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.