On March 3rd, Casco Baykeeper Ivy Frignoca strolled the South Portland shoreline near our office. She was shocked to see green algae growing at the base of the Spring Point seawall. In the past, we have not begun to see widespread nuisance algal blooms until late May or early June. Community Engagement Coordinator Sarah Lyman issued an alert to our observing network. Soon, our volunteer Water Reporters were posting images of green algal blooms in coves around the Bay.
What could be fueling these algal blooms so early in the year? Staff Scientist Mike Doan searched for answers by looking at our water quality data. At our Continuous Monitoring Station, the bright green growth did not correspond to a spike in chlorophyll levels, normally associated with a phytoplankton bloom. Our data did show that we have had an extremely warm winter. Heavy rains may have flushed nutrient-laden meltwater into coastal waters weeks earlier than in past years. In fact, just a few days prior to Ivy’s sighting in South Portland, we had an intense rain event. Lengthening daylight and warming temperatures also likely contributed to the emergence of these blooms.
Sarah encourages more people to volunteer as Water Reporters to track these early indicators of excess nitrogen. “Each volunteer can adopt a specific location around the Bay to observe weekly, ideally at low tide, any time between an hour before and after. Images of algae from ‘good’ amounts to ‘concerning’ amounts are helpful because we can’t predict where and when a small patch of algae may become a nuisance algal bloom.”
The blooms we have seen this month are small, but excess nitrogen can stimulate algal growth beyond healthy amounts for the ecosystem. Nuisance algal blooms can cover tidal flats with a thick carpet of “green slime,” smothering animals below the mat and preventing juvenile clams from settling into the mud.
If you are interested in joining our effort to track these blooms, learn more at cascobay.org/water-reporter or call Sarah at (207) 370-7553.