On January 24, 2017, Research Associate Mike Doan stood before an audience of volunteers and supporters at Friends of Casco Bay’s Annual Members Meeting. He reminded them, “A year ago at this volunteer celebration, we proposed the idea of Nabbing Nitrogen, to get people involved in water quality monitoring on one day, at one moment in time. If we’d recruited 50 volunteers, we would have considered it a success. More than 170 people signed up to volunteer to sample for nitrogen!”
Our Nabbing Nitrogen event became a flash mob, where volunteers scooped up jars of seawater at precisely 10:10 a.m. on July 10, 2016. The weather was awful, so we had to cancel plans for boaters to sample out on the water. Though limited to land-based sites, volunteers would not be deterred. They lined the shoreline of Portland and South Portland on both sides of the Fore River. Mike championed, “It was the volunteers and their enthusiasm and energy, despite the rain, that made the event such a success.”
On that particular morning, we experienced a heavy rain that followed a long dry spell. This made for ideal conditions for collecting data on a storm event. We collected and analyzed 90 samples, which Mike used to construct a map of nitrogen levels around Portland Harbor at this one point in time. He wasn’t surprised to find that nitrogen levels were higher than normal.
Why do we worry about too much nitrogen in Casco Bay?
Nitrogen is an essential plant nutrient, critical for growing. In the ocean, nitrogen nurtures plant growth, from single-celled phytoplankton to large seaweeds. But too much nitrogen triggers excessive algae growth that can turn the Bay green. When the plants die, decomposing bacteria remove the oxygen from the water and release carbon dioxide, making the water more acidic.
Over the last 100 years, the amount of nitrogen available for plant growth has more than doubled, thanks to the invention of commercial fertilizers and the increase in the burning of fossil fuels. Human sewage, air pollution, and rainwater washing fertilizers and animal wastes off yards and farms add excess nitrogen to our coastal waters.
Mike said, “Do you remember last summer, when we saw large mats of green algae in Back Cove in Portland and Mill Cove in South Portland? Those carpets of ‘green slime’ smothered anything trying to live underneath them. In South Portland, we also found that the mud beneath the algal mats was highly acidic.”
Too much nitrogen in the water can impact the nursery of the sea. “Phytoplankton and seaweeds can make the water murky, limiting sunlight to eelgrass,” explained Mike. “We are fortunate that Casco Bay has a lot of eelgrass. Eelgrass is our ‘rain forest.’ It serves a number of purposes: it holds sediments in place, helping to prevent erosion, dampens wave action, which protects the shoreline, and most importantly, provides hiding places for juvenile marine animals.”
Photo credit: Dave Dostie
We will meet with sewage treatment plant operators and stormwater managers to discuss what all the data means.
Already, with the help of our volunteers and great media coverage of our event, people know that there is a lot we each can do to reduce the flow of nitrogen into the Bay. Casco Baykeeper Ivy Frignoca told the audience at our Annual Meeting that they can help by:
- Not using fertilizer on their yards and practicing BayScaping to minimize the need for lawn chemicals
- Keep rainwater from running off our driveways and yards
- Replacing lawns with rain gardens or permeable pavement
- Support efforts by local municipalities to reduce nitrogen-laden sewage overflows into the Bay
- Support our work with the Maine Department of Environmental Protection to set responsible limits on nitrogen discharges into coastal waters
Photo credit: Dave Dostie
WMTW Meteorologist Sarah Long was one of the many volunteers that participated in this sampling event. You can see her coverage of the event here: http://www.wmtw.com/article/citizen-scientists-help-keep-casco-bay-healthy/8972719.
