Blue-green algal bloom occupies several kilometres of Thames River near Chatham, Ont.

Researchers are waiting on the results of samples taken from blue-green algae currently dominating portions of the Thames River near Chatham, Ont. in an attempt to better understand the nature of the algal bloom. 

One of the goals is to determine whether the cyanobacteria responsible for the bloom — currently thought to be bacteria from the genus Aphanizomenon — is producing toxins that could potentially harm humans. 

Mike McKay, executive director of the University of Windsor's Great Lakes Institute for Environmental Research (GLIER) said he was "really surprised" when he learned about the bloom. 

"Most of the focus this summer has been on the algal blooms in Lake Erie," he said, referring to a large bloom that at one point reached Colchester Harbour. 

"We've been sampling that Thames monthly, bi-monthly since May and really haven't seen anything of note."

McKay said this latest bloom "sort of came out of the blue."

GLIER researchers learned about the bloom on Monday, after researchers from the Lower Thames Valley Conservation Authority (LTVCA) sent word that water in the river near Chatham was green. 

"We rallied our troops and responded," said McKay. 

Jason Wintermute, the LTVCA's manager of watershed and information services, said the algal bloom is reminiscent of a similar bloom that spread through the Thames River in 2017.

That bloom didn't produce any toxins, but there's no guarantee that this latest bloom is harmless. 

"We hope that this one doesn't get as bad as that," Wintermute said, in reference to bloom's overall size. "We hope no toxins get produced from this algal bloom either."

Wintermute explained that some of the cyanobacteria sometimes responsible for the development of algal blooms are capable of producing neurotoxins that are harmful to humans and other animals. 

Anyone who comes across an algal bloom should keep their distance until researchers have a better understanding of the bloom's toxicity. 

"We've had a lot of cases this year of pets dying, because the pet's been playing close to a riverbank or a reservoir or a lake bank and there's been an algal bloom," he said. "When you have water this green, and if it's producing toxin, it doesn't take much for the pet to have an acute dose of the toxin and succumb to it."

McKay added that residents of Chatham shouldn't be concerned about harmful effects to their water supply, as the city's drinking water isn't derived from the Thames River. 

"Even if the drinking water intake was in the Thames, it's likely that the water treatment plants, as we see along Lake Erie [and] along Lake St. Clair, have adequate processes to remove any potential toxins that could be harmful to humans."

McKay also said the bloom may not spread very far. 

"It may just stay concentrated in this area for days," he said. "I think there's weather coming up in the next days, so that actually will probably be helpful in breaking up the bloom."

Researchers from Canada and the U.S. teamed up earlier this summer for the second annual 'HABs Grab,' to collect water samples from 200 locations to map a harmful algal bloom (HAB) on Lake Erie.