Algae Blooms Throughout Three Bays Estuary Threaten Fin Fish and Raise Questions about Ecosystem Health

Tuesday, August 16, 2016

Media Contact:  Lindsey B. Counsell, Exec. Dir.

(Osterville, Mass.) – This past weekend, the talk around boatyards, private piers and public docks throughout the 1,251 acre Three Bays estuary was about those large patches of unsightly and scary-looking algae blooms that most likely resulted in a small batch of dead fish by the Bay Street Landing.

“Algae blooms deplete the water of oxygen and the result is fish die,” said Lindsey B. Counsell, executive director of Three Bays Preservation Inc. “We have been monitoring oxygen levels in the bays and they are trending below what is needed for sea life to survive in the deeper basins and shallow coves,” he added.

Algae blooms and the resulting fish kills, however, are merely the symptom of the most critical problem that has ever faced the Three Bays estuary. 

“Excessive growth of algae in a coastal bay is often an indication of excessive nitrogen loading; this is a common occurrence in many Cape Cod coastal bays and ponds,” according to Hauke Kite-Powell, Ph.D., a Research Specialist at the Marine Policy Center of the Woods Hole Oceanographic Institution (WHOI) and a Lecturer in the Ocean Engineering Department at Massachusetts Institute of Technology (MIT.) In fact, the Massachusetts Estuaries Project reports that the Three Bays system that includes West, North and Cotuit Bays, exceeds a critical threshold for nitrogen, which is harmful to water quality, human health, and toxic for wildlife including fish and shellfish, and plant life.

“August is known as a happy time for all algae because the water is nice and hot,” explained Karen Malkus, the Coastal Health Resource Coordinator at the Health Division in the Town of Barnstable. And has it been hot this summer:  those high temperatures play an adverse role in the lives of fin fish.

Worsening the problem is the higher than average number of people who summer on the Cape, resulting in an increased use of septic systems and road runoff, from lawn fertilizers to detergent from folks washing their vehicles, all of which eventually flow into the marine environment. Algae consume those nutrients.

"We at Three Bays Preservation have been warning the community this would happen. Excess nitrogen pollution from septic systems, combined with hot temperatures have resulted in excess algae blooms which in turn deplete oxygen from the water,” replied Michael J. Egan, president of Three Bays Preservation. “We now witness fish kills from oxygen depletion in North Bay. Shellfish will die next. The eelgrass is already dead. This is the worst I have seen it in my 20 years of living here. We need to improve our wastewater management to prevent nitrogen from septic systems from entering the estuary," he added.

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Three Bays Preservation Inc. is dedicated to restoring and protecting West, North and Cotuit Bays, and the coves, ponds, rivers and streams that form our watershed and ecosystems. Since 1996, Three Bays Preservation Inc. has continued stewardship efforts through applied science, educational programs, and ecosystem-based management practices. To learn more, visit Three Bays Preservation online at


Theresa M. Barbo
Communications Consultant


Co-Principal/Marketing Advisor
The Mitchell Jones Agency