Seasonal blooms of cyanobacteria and other algae are common occurrences in lakes and may naturally increase in frequency as lakes become richer in nutrients and oxygen deprived, a process called eutrophication. However, increasing evidence shows that human activity is accelerating eutrophication and contributing to the increases in cyanobacteria blooms.

Such increases may have detrimental effects on lake ecosystems and water quality. Deleterious effects may include the development of surface scum, depleted oxygen levels, and the production of toxins that can negatively affect aquatic life and humans. Past research in Pacific Northwest lakes and reservoirs suggests a strong relationship between nutrient availability and blooms, but no clear correlation between the two factors. Similarly, research has also shown that grazing of algae by zooplankton influences bloom dynamics, but again there has been no proven connection.

In an ongoing research project, WSU researchers Gretchen Rollwagen-Bollens and Stephen Bollens are investigating the interaction of nutrient availability and zooplankton grazing in four Washington lakes and reservoirs, all at different stages of eutrophication, to more accurately define the balance of factors that influence cyanobacteria blooms and to better predict when blooms may occur.

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