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SALT LAKE CITY — Toxic algae might be to blame for the deaths of about 30 wild ducks at a popular Salt Lake City park earlier this month.
Wildlife biologists, state environmental experts and Salt Lake City officials are now urging visitors to keep their children and dogs away from algae mats, because they are considered the most at-risk of illness as a result of the algae's toxins.
"Pets, particularly dogs, tend to be the most vulnerable to harmful algal blooms largely because a dog is much more likely to directly ingest or eat this harmful algae, whether that be through drinking water, swimming or playing in the water," said Hannah Bonner, an environmental scientist for the Utah Division of Water Quality.
The ducks were found dead near the Liberty Park pond between July 8 and July 9, according to Utah Division of Wildlife Resources spokeswoman Faith Heaton Jolley. She said three of the carcasses were submitted to a lab for testing on July 12 and preliminary tests ruled out avian influenza, though it did not indicate a specific cause of death.
The division's wildlife veterinarian suspects either botulism or another toxin caused the birds to die, but additional test results are still pending, Jolley said.
"Samples of algal material" were collected from the pond's southern shoreline — an area where the pond had overflowed this spring and has since receded, Jolley said. Test results on that material revealed cyanobacteria with some hepatotoxin, chemicals found in harmful algal blooms. Signs have since been posted around the pond warning visitors of the discovery.
Bonner explains that harmful algal blooms, which can grow in lakes, rivers and ponds, are a species of algae that produce these types of toxins as a part of their natural lifecycle. Algal blooms tend to thrive on warm and sunny days and they also need nutrients like nitrogen and phosphorus, which often enter the ecosystem through "human nutrient pollution," she said.
These typically look like various shades of green or blue, but can also be red, pink, white, gray or purple, according to the Utah Division of Water Quality. The agency says the algal blooms often look like "spilled paint, green globules, surface scum, foam, floating mats or grass clippings," too.
The division has active algal bloom advisories issued in a handful of places across the state, including Utah Lake and Otter Creek Reservoir. Ponds and other shallow bodies of water are considered more prone to algal blooms, especially if they are located by human activity.
While algal blooms may cause skin irritation through direct contact, they can also cause abdominal pain, headaches, vomiting, diarrhea, kidney or liver damage and neurological symptoms in people and animals. It can lead to permanent organ damage and be fatal.
Dogs can be particularly vulnerable because some of the toxic algal species produce scents that attract dogs to eat them, Bonner said. Pet owners should watch for excessive drooling, vomiting or diarrhea, stumbling or muscle tremors, loss of appetite, excessive scratching, rashes or hives, difficulty breathing or weakness, seizures and paralysis, as these are typical signs of exposure to cyanobacteria.
"These aren't a joke," she said. "There are severe health effects to both humans and dogs from harmful algal blooms."
Contributing: Adam Small
