NEW BEDFORD — A video posted on social media depicting dozens of dead fish in and around the pond at Buttonwood Park is under investigation, but city officials say its not caused by the recently implemented swan boats, as some have suggested.

A video posted on Facebook and shared in a local group included the caption, "Buttonwood Park pond in New Bedford today. Hundreds of dead and dying fish, ducks and geese soon to follow. Chemicals added to "clean the pond and make it healthier" in reality only to allow better operation of swan boats ?????? horrible and so cruel."

According to Jonathan Carvalho, public information officer for the City of New Bedford, the City's Environmental Stewardship Department and Health Department, along with the Massachusetts Division of Fisheries and Wildlife, are currently testing water quality to determine the cause.

He says as of now, tests indicate a low dissolved oxygen level in the pond, which could be caused by algae buildup in the pond.

"A bystander in the video suggests the swan boats may have been the cause of this," Carvalho said. "The swan boat company uses no chemicals to operate or clean the boats, only water. The swan boats have been in Buttonwood Pond for nearly three months, (and) this is the first report of dead fish at the pond."