Does Selenium Offset Methylmercury Toxicity Across Trophic Levels in Chlorella Pyrenoidosa and Aeolosoma Variegatum?

Methylmercury is a potent neurotoxin that impairs functioning of the nervous system, and selenium is known to provide a protective effect against methylmercury. Experiments were run to investigate the offsetting of methylmercury toxicity by selenium across trophic levels at the base of the aquatic food chain. A primary producer, Chlorella pyrenoidosa, was exposed to methylmercury in the presence or absence of selenium. The subsequent biomass was fed to a primary consumer, Aeolosoma variegatum. Results showed that methylmercury decreased the maximum density of Chlorella, which selenium did not offset. When consuming selenium in methylmercury contaminated water or when consuming dietary methylmercury with dietary selenium, Aeolosoma populations experienced a rescue effect against methylmercury. Understanding safe levels of dietary selenium that provide population level protection against methylmercury is a critical step towards managing mercury in contaminated ecosystems. More research is required to determine the threshold range of safe dietary selenium for representative species.