Effects of harmful algal blooms on stress levels and immune functioning in wetland-associated songbirds and reptiles

Harmful algal blooms (HABs), caused primarily by nutrient input from agricultural runoff, are a threat to freshwater systems worldwide, and further predicted increase in size, frequency, intensity due climate change. HABs occur annually the Western Basin of Lake Erie (Ohio, USA), these become toxic when dominated cyanobacteria that produce liver toxin microcystin. Although we making substantial inroads toward understanding how microcystin affects human health, less is known about effects on wildlife exposed HABs. Wetland-associated songbirds (barn swallows, Hirundo rustica, red-winged blackbirds, Agelaius phoeniceus) reptiles (Northern watersnakes, Nerodia sipedon, painted turtles, Chrysemys picta) were sampled wetlands chronically high levels prolonged HAB event, unexposed, control wetlands. Physiological stress several measures immune functioning compared between HAB-exposed populations. levels, measured as heterophil:lymphocyte ratios, higher barn Northern watersnakes chronic individuals, but turtles did not differ physiological individuals. Neither swallows nor blackbirds differed populations, had bactericidal capacity than snakes, lower turtles. These results suggest even do cause direct mortality wildlife, they can potentially act stressor across taxa, furthermore may compromise some species.