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Report details rapid warming in Casco Bay

Murray Carpenter
Maine Public
Upper Casco Bay, near the mouth of the Presumpscot River.

Friends of Casco Bay released a report Wednesday showing that the waters of the bay are warming at roughly one degree per decade, which the group says will have significant ecological impacts.

Casco Baykeeper Ivy Frignoca says the rate of temperature change is alarming. In some recent winters, the bay hasn't dipped below 32 degrees, which creates a comfortable environment for invasive green crabs.

And in summer, the nearshore waters can be as warm as 80 degrees. Frignoca says the warmer water — which holds less dissolved oxygen — combined with algae blooms, can cause problems like the die off of softshell clams in Maquoit Bay over the summer.

And she says warming waters can also harm eelgrass, which is critical habitat for many species in the bay.

"The trends we are observing are causing concern, and confirming that Casco Bay is changing, and changing quickly, in response to excess greenhouse gas emissions," Frignoca says.

The temperature data also show that the Bay's three warmest years on record have occurred in the past five years.

Murray Carpenter is Maine Public’s climate reporter, covering climate change and other environmental news.