Microcystin Toxin and Associated Trophic Level Effects

Microcystin toxin is a known environmental stressor with implications for ecosystem harm throughout many inland waterways in California. This purported freshwater toxin has recently emerged in the marine environment in Monterey Bay. Microcystin abundance and frequency, as well as environmental variables that drive toxin production in the Monterey Bay area were examined by deploying Solid Phase Adsorption Toxin Tracking (SPATT) samplers and evaluating water samples for 3 years. Microcystin was found in 15 of 21 monitored sites and was shown to be correlated with anthropogenic nutrient loading. Because it is relevant to identify an indicator organism to better monitor this toxin, uptake and release of microcystin toxin in California mussels (Mytilus californianus), and commercial oysters (Crassostrea sp.) were also examined. To provide environmental relevancy Mytilus sp. were also collected at 4 sites in San Francisco Bay for 6 months and analyzed for microcystin toxin. The results indicate that mussels purge microcystin toxin slowly, while oysters released toxin more quickly, however, both have the ability to retain toxin for 8 weeks post-exposure. To investigate potential effects to marine and estuarine birds at upper trophic levels the use of Whatman® FTA® blood sample collection cards were evaluated in tandem with competitive enzyme-linked immunosorbent assay (ELISA), and this method was shown to have utility for postmortem analysis and large die off events. Blood was also collected from birds admitted to rehabilitation in Monterey Bay between 2011-2015 and two groups of waterbirds tested positive for microcystin toxin. The extensive manifestation of microcystin in the Monterey Bay area exhibits the need for better monitoring and management of this toxin. Management decisions made at the terrestrial level, may now impact freshwater, estuarine, and marine ecosystems, particularly given the demonstrated capacity for bio-accumulation in shellfish. The identification of a potential bio-indicator through this study, could be used to inform the current Mussel Watch Program or could aid in establishing an analogous monitoring program specific to this toxin. Because current data on the effects of toxic algae on waterbirds is meager, this study addresses this deficiency by identifying a new technique for detecting microcystin in upper trophic levels