Extensive algae bloom threatens marine life in Casco Bay

A large algae bloom that can create low-oxygen dead zones in ocean water is being monitored by state authorities in Casco Bay.

Karenia mikimotoi, the phytoplankton causing the widespread bloom, is not hazardous to humans, but fish kills and have been reported during blooms of the species in Asian and European countries, according to the Department of Marine Resources.

The toxicity of the algae is not fully understood, but it is believed that die-offs are caused by the creation of a low-oxygen environment created by the bloom itself and a toxin carried by the phytoplankton. Shellfish like mussels, clams and oysters, fin fish and crustaceans like lobsters could be affected by the bloom.

There are preliminary reports of softshell clam die-offs in Harpswell, Freeport and Brunswick, and is trying to determine the cause, the department said in a news release Tuesday. The bloom is believed to cover most of the bay.

“We are not able to predict if a low-oxygen event will occur or if the toxins it is known to produce will impact fish or shellfish,” said Kohl Kanwit, director of the department’s public health bureau in a statement.

The department on Tuesday notified seafood dealers, shellfish harvesters and aquaculture lease holders in Casco Bay of the problem. Testing in the bay will continue for dissolved oxygen levels and the presence of Karenia mikimotoi.

The department is asking anyone who observes a die-off of marine organisms in the Casco Bay region to report it to the marine patrol.

This story will be updated.

Source: Portland pressExtensive algae bloom threatens marine life in Casco Bay