A recent study published by Harmful Algae on Oregon’s Detroit Reservoir unexpectedly revealed a dangerous algal bloom. The research was meant to analyze the cyanobacteria population, but an unforeseen twist redirected its focus. Algal blooms are a common yet dangerous phenomenon that occurs in lakes and reservoirs due to the explosion of cyanobacteria, also known as blue-green algae. With sufficient sunlight, these microorganisms can easily create nutrient-rich food and reproduce. This expansion can cause a widespread algal bloom, potentially contaminating water. According to the study by Oregon State University, these blooms occur anytime between spring and fall, and any consumption or direct contact could have dire consequences.
Some cyanobacteria can produce liver toxins and neurotoxins, and some can even cause gastrointestinal illness if consumed. Direct contact can also lead to infections or rashes on the skin. “Not every cyanobacterial bloom is toxic, but it is always wise to follow the rule of avoiding contact when there’s green growth in the water,” said Theo Dreher, professor emeritus of microbiology at the university. “Potential exposure to cyanotoxins is of public health concern, and blooms particularly pose a threat to dogs entering lakes,” he added. The Detroit Reservoir — the subject of the study — is located in the foothills of the Cascade Range. The area is a famous recreational spot in Oregon’s capital city of Salem.
Dreher studied the cyanobacteria that were involved in the 2018 water scare in Salem. The study determined two different strains of Dolichospermum cyanobacteria. One produced a form of cylindrospermopsin, and the other released a different type of microcystin. The latter is a liver toxin and can potentially be carcinogenic. Although the other strain can also severely impact multiple organs, it is relatively less harmful than microcystin. The algal bloom contributed to Salem’s infamous water scare, as even small concentrations of the algal strains found in the drinking water taps prompted authorities to alert the public. A do-not-drink advisory was issued to vulnerable groups like infants and pregnant women.
The devastating episode in the history of the city led to the demise of more than 30 steers from drinking from drinking the contaminated water. The researchers analyzed the two strains found in the reservoir during their 12-year study period until a twist came their way. In 2018, the researchers observed a “regime shift” where cylindrospermopsin became more dangerous than microcystin, in contrast to what they previously analyzed. “We found that the lake underwent a regime shift in 2018, switching from one where cylindrospermopsin was the main concern to one in which microcystin is the main concern,” Dreher said. The study highlighted that the sudden increase of a less-dominant algal population is more concerning than the stable presence of a dominant one.
“Sudden population shifts can occur without an obvious cause,” he added. “The change in toxin status was caused by changes in the accumulations of the two previously identified Dolichospermum strains,” he explained. Nevertheless, the researchers believe that they have all the information about which strain produces substances that are toxic. Therefore, advanced genetic monitoring tools can allow them and other scientists to track the toxin production. This process will eventually help provide “early warning of a toxic bloom.” Scientists hope that early detection and faster communication will prevent large-scale algal bloom contamination.
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