Heavy Winter Snows Could Yield Big Chesapeake Algae Blooms

If the region has a snowy winter, increased runoff could feed bacteria growth and algae blooms in the Chesapeake Bay next summer, experts say.

Large algae bloom tendrils in the Chesapeake Bay. Photo courtesy of Kim Reece/Virginia Institute of Marine Science.
Large algae bloom tendrils in the Chesapeake Bay. Photo courtesy of Kim Reece/Virginia Institute of Marine Science.


Capital News Service

If Maryland experiences heavy snowfall this winter, biologists predict the Chesapeake Bay could experience above-average levels of bacteria and toxic algae blooms during the summer.

While human pollution can cause bacteria growth and algae blooms, natural factors, such as climate conditions, dictate their frequency. The amount of snowfall each winter is linked to algae bloom instances in the summer, since spring snowmelt causes runoff, and more nutrients to enter the bay.

“Some relation does exist between higher harmful ... blooms and increased runoff related to the amount of snow, rather than just winter temperatures,” University of Maryland Atmospheric and Oceanic Science Professor Raghu Murtugudde said. Maryland is expected to experience warmer than normal temperatures this winter, but also excess amounts of snowfall, so “harmful algal blooms may well turn out to be above normal next summer.”

Water temperature, the bay’s salt content, and nutrient levels determine bacterial growth.

“Warmer temperatures mean more growth,” Maryland Department of Health and Mental Hygiene’s Environmental Health Bureau Director Clifford Mitchell said, so the summer is generally the most high-risk time of the year for contamination. However, “hundreds of thousands of people ... [enjoy] the bay every year completely safely… I don’t discourage people from going in the bay.”

Potential for infection and toxic exposure is generally not worrisome, although Maryland residents could benefit from avoiding recreational activity in the bay during certain high-risk periods when bacteria and algae blooms are high in frequency and toxicity, Mitchell said.

In certain situations however, the state health department issues swimming warnings because of higher risks of bacterial infections. Heavy downpours lead to increased sewage runoff, which could potentially contain strains of E. coli or promote toxic algae blooms, Mitchell said.

According to Mitchell, although “a little consumption of bay water isn’t worrisome … we do worry about infections that come from exposure.”

There’s a chance of exposure to bacteria and toxins for people who do recreational activity in the bay with open wounds, especially for those with compromised immune systems. Raw seafood consumers are also at a small risk of exposure.

As for bacteria that grow naturally in the bay, Vibrio is the Department of Health’s main concern, but of all the people who swim in the bay each year, only about 30 to 50 individuals develop cases of Vibrio, which in its mildest form causes skin infections and stomach ailments.


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