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Your Environment. Your Health.

Daily Cycles in Harmful Algal Blooms

Robert Michael McKay, Ph.D.
Bowling Green State University

An NIEHS-funded study shed light on harmful algal bloom (HAB) changes during different times of day. HABs occur when toxin-producing algae grow excessively in a body of water. Environmental factors such as light, temperature, and nutrient levels can play a role in production of toxins that can seriously harm people, fish, and other parts of the ecosystem.

The researchers collected samples from a toxic Microcystis cyanobacteria bloom in Lake Erie in 6-hour intervals over a 48-hour period and analyzed DNA to determine which genes were active during different parts of the day. Specifically, they looked at genes involved in metabolic functions, such as photosynthesis, nutrient uptake, cell division, and toxin production.

They found that patterns suggesting that genes related to cell division and acquisition of nitrogen, a critical nutrient for growth, were most active during the day. Similarly, genes related to stress response, such as temperature, had increased expression during the day. In contrast, genes expressed during the night were associated with carbon fixation, in which plants can convert inorganic carbon to sugar for energy, and phycobilisome protein synthesis, which allows algae to use wavelengths of light much deeper in the water column.

According to the authors, these findings explain differences in how genes are expressed during different times of the day and may help inform strategies to predict HABs and mitigate these events.

Citation: Davenport EJ, Neudeck MJ, Matson PG, Bullerjahn GS, Davis TW, Wilhelm SW, Denney MK, Krausfeldt LE, Stough JMA, Meyer KA, Dick GJ, Johengen TH, Lindquist E, Tringe SG, McKay RML. 2019. Metatranscriptomic analyses of diel metabolic functions during a microcystis bloom in western Lake Erie (United States). Front Microbiol 10:2081.

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