UT study confirms wildlife health is impacted by algal toxins, to varying degrees

Aug. 9—When algal blooms hit, animals have to fight off toxins too.

While it's still unclear which ones are most susceptible and how well their natural systems work in warding off the threats, a University of Toledo research paper being published in the journal Science of the Total Environment in September shows that impacts likely vary from species to species.

Lead author Jeanine Refsnider, a UT environmental sciences associate professor, said her latest project is a continuation of an earlier one which focused largely on turtles.

For this report, she and others working with her studied barn swallows, red-winged blackbirds, Northern watersnakes, and painted turtles in two locations: the Ottawa National Wildlife Refuge in Ottawa County and Grand Lake St. Marys in west-central Ohio.

They documented some physiological impacts, such as stress and weakened immune systems, along with behavioral changes.

"I think it's very likely there are impacts to other wildlife," Ms. Refsnider said.

Those two sites were chosen so the same species could be studied, she said. Animals from the same general part of the country were desired to avoid having other variables come into play.

In all cases, they found impacts, but not uniformly distributed. For example, there were more signs of stress among songbirds and snakes.

Turtles seem to manage stress better than the other three species but had weaker immune systems. Snakes, despite their susceptibility to stress, seemed to have something jumpstart their immune systems.

The Ottawa refuge, along part of the western Lake Erie shoreline, was actually used as the control. Animals were trapped and blood samples were taken in late spring and early summer, weeks before the lakefront usually gets its annual slug of cyanobacteria, or blue-green algae, after the summer heat sets in, Ms. Refsnider said.

Large mats of toxin-producing cyanobacteria are what scientists called harmful algal blooms.

Grand Lake St. Marys has such blooms throughout much of the year, whereas it's still more of a seasonal phenomenon to the much larger and colder western Lake Erie.

Although the two bodies of water are usually dominated by different HABs — microcystis in western Lake Erie and planktothrix in Grand Lake St. Marys — they produce the same toxin, microcystin.

That toxin is the one of primary interest to the U.S. Centers for Disease Control and Prevention because of its capability of killing humans. Some 75 patients at a kidney dialysis center in Brazil died from exposure to it in the mid-1990s when a treatment system malfunctioned.

"We sort of predicted the animals would have higher stress levels and worse immune systems," Ms. Refsnider said. "Three of the four did have higher stress levels. We didn't see that with turtles. They don't ever seem to show the same stress levels. They seem very robust and exhibit the stress they're under in different ways."

Of course, there's more to be learned not only about other species but what might happen if fighting off toxin-induced stress becomes more chronic.

"The problem is if you're exposed to stress for a long time, your immune system is down," Ms. Refsnider said. "You can't necessarily predict what the impact is going to be on all species."

She said the research is important because scientists need to know more about both the human health effects and the wildlife effects of exposure to algal toxins.

"While harmful algal blooms aren't directly causing exposed wildlife to die, the research suggests they are causing reptiles and birds to have generally worse health, putting their system at a disadvantage," Ms. Refsnider said. "The reptiles and birds are ramping up their response, which can be harmful if you have a constantly elevated stress level in your body."

Co-authors included some UT undergraduate students who collected blood samples.

One was Brittany Holliker, a 2020 UT graduate who has since gone on to do field work in at least a couple of different states.

"It is incredible that my undergraduate research is now part of a published study that can be used for wildlife conservation," Ms. Holliker said in a statement issued by UT, adding that her experience at UT "definitely helped me launch my career in wildlife biology."

First Published August 9, 2021, 9:00am