Students in Ed Laine’s Coastal Oceanography course teamed up with the Friends of Casco Bay to collect data on the health of eelgrass in Harpswell Sound and the Fore River in South Portland. The data from their multi-faceted study may help the state Department of Environmental Protection better understand the local marine ecology and draft regulations to protect it.
“Eelgrass is an important indicator of ecosystem health,” said Angela Dubois ’01, a biologist with the DEP’s Division of Environmental Assessment.
Excess nutrients such as nitrogen and phosphorus from human sources can cause phytoplankton blooms, which shade the eelgrass from the sunlight they need.
“But we won’t be able to say that changes in eelgrass are definitely due to nitrogen levels,” Dubois said. “Eelgrass populations fluctuate a lot on their own, so it’s hard to tease out the human effect.”
“I cautioned the students that there wouldn’t be any definitive answers,” Laine said.
The DEP has been following the health of eelgrass for about 10 years, but the state does not have the resources to conduct the type of in-depth water testing that the students did this spring.
The class of mostly sophomores divided into two teams of 12; one focused on Harpswell Sound at the Coastal Studies Center, the other in the Knightsville neighborhood of South Portland, where die-offs of eelgrass have been observed.
The first thing they did at each site was drop a sonde into the water. For the next 24 hours, the instrument measured fluctuations in temperature, salinity, pH, turbidity, dissolved oxygen and chlorophyll levels. After 24 hours, water samples were sent to an EPA-approved lab for analysis. They also submerged a fluorometer, which is a more sensitive chlorophyll-reading device that collects data for 24 hours.
Pairs of students then worked in four-hour shifts, collecting 250-ml water samples every hour. The water was pushed through a filter, and the filters were preserved in acetone, put on ice and sealed in lightproof coolers to halt naturally occurring biological processes. They were later brought back to campus to test for chlorophyll.
The concentration of chlorophyll is important because it gives an indication of biological activity, Laine explained.
Another small group of students slogged through the mud during an outgoing tide to locate beds of eelgrass. They returned later by boat using a viewscope to look into the water for the grass. They used GPS to plot the locations in order to update existing Maine Department of Marine Resources maps. According to those maps, the eelgrass population shrank by 30-50 percent in some areas between 1995 and 2004, but the students discovered an increase in the eelgrass population.
“Doing this kind of service learning project helps them think and organize their minds like scientists,” Laine said. “They are working with real data that has an impact on the real world where the outcomes can be messy.”
Enthusiasm for this course is indicative of a resurgent interest in geology since the department was transformed into the interdisciplinary earth and oceanographic science. In the recent past, there were only 3-11 geology majors in a given year, Laine said. This year, 27 of the students in biogeochemistry became majors.