Groundbreaking eelgrass pilot restoration takes root in Casco Bay

A chilly wind sparked waves on Oct. 17 as Glenn Page, global lead of the Collaborative for Bioregional Action Learning and Transformation (COBALT), motored from East End Beach in Portland to Cousins Island on a 30-foot hull. Staring at his restoration “game plan,” his eyes darted from diving brief to horizon — back and forth like the bobbing sailboats anchored nearby. 

Eelgrass, or Zostera marina, is found along the Atlantic coast from Chesapeake Bay to Maine, but its population has declined drastically in recent years.

According to the state Department of Environmental Protection, more than 50% of native eelgrass has receded. Many factors have contributed, from stormwater pollution to invasive green crabs munching on the grass beds. 

“There has been a great loss,” Page said. “But hope remains.” 

Hidden out of sight, the aquatic plant plays a key role in coastal environments and has captured the attention of scientists.

Physically, eelgrass traps sediment, shielding shorelines from erosion. Chemically, it removes nitrogen through respiration, buffering ocean acidification. Ecologically, it provides a habitat for dozens of juvenile species, from striped bass and blue crabs to lobsters, mussels and bay scallops.

Since 2021, COBALT’s Team Zostera has surveyed area meadows to assess remaining eelgrass, identify the species’ reproductive season and determine the optimal time for collection and seed germination. Working with the Casco Bay Estuary Partnership, Friends of Casco Bay, Maine DEP and U.S. Environmental Protection Agency, the team investigated the reasons behind the decline and began exploring solutions, including transplantation. 

“Today is a landmark day,” Page said, addressing the crew. “As we prepare for transplantation, we must remember that it’s a learning-by-doing process. We will likely learn from failure. Even still, resilience assessments will help inspire public involvement and inform future conservation.” 

The first location, Cousins/Littlejohn Island, was selected as one of the two sites for the pilot restoration project, the other being Mackworth Island. The nine underwater plots at both sites aim to test optimal seeding methods: three for hand-cast seeds, three for biodegradable seed-filled tea bags secured with bamboo skewers and three control plots.

Janelle Goeke, a staff scientist with the Casco Bay Estuary Partnership, sat at the bow, fingers wrapped around a warm tumbler of coffee as she anticipated the day ahead.

“Eelgrass is my passion project,” said Goeke, acknowledging the movement at the state level to have the plant listed as a species of concern. “One of the main incentives for pilot-scale restoration is its ability to buffer winter storms. Eelgrass reduces wave energy, thereby minimizing the impact of severe weather events onshore.”

Unlike terrestrial planting, where soil amendments and environmental conditions for optimal growth are well known, researchers are beginning to understand the requirements for aquatic plant germination. 

Other regions in New England have succeeded with large-scale seeding restoration, while previous efforts in Maine have only involved relocating eelgrass shoots. 

This project is the first in the state to focus on harvesting, processing and redistributing of eelgrass seeds.

Transplantation preparation 

Before seeding, Cousins/Littlejohn and Mackworth islands were selected as ideal sites due to their depth (10-12 feet), appropriate sediment and absence of existing eelgrass.

Beneath gray skies on that October day, the team prepared for the demonstration by marking the corners of a 16-by-16-meter site with surface floats labeled T 1-3, C 1-3 and H 1-3. The “T” denotes the cells treated with teabags, “H” indicates the hand-cast treatment and “C” represents the control group.

“There’s always some variability,” Goeke said. “Seed-filled teabags and hand-cast seeding is the same concept, but we have control groups to test the best method.” 

Each biodegradable teabag contained 200 seeds. Inspired by Phil Colaruzzo, a marine biologist at the EPA Region 1, Page chose bamboo skewers because they naturally decompose within two months and provide a protective shell to guard against winter storms.

Beneath the harvest moon

Seeds were scattered after the Hunter Moon, which brought a high lunar tide at 11:11 a.m. — an omen that Page was sure would promise high diving visibility and positive results.

Three Team Zostera divers led the demonstration: Page; Lucy Dutton, Bowdoin College class of 2025; and Allison Fog, a marine science graduate student at the University of Southern Maine. The venture was their 27th project-related plunge.

Previous dives at Fort Gorges, Long Island, Chebeague, Sturdivant Island, Haskell, Cliff Island and Upper Flag were essential for documenting eelgrass reproductive seasons. Spathes were stored at the Schiller Coastal Studies Center in aerated tanks, maintained at a comfortable temperature of 77 degrees Fahrenheit, with a drain at the bottom to allow seawater to flow continuously. 

During this year’s COBALT Bioregional Learning Journey, participants visited Orr’s Island to assist with seed processing.

Page initially predicted 20,000 seeds would be processed from the 1,100 shoots collected. However, the actual number was an impressive 53,000.

Dutton will use some of these seeds to test germination rates for her honors thesis. The rest were allocated to the pilot transplantation, with each site receiving 20,000 seeds.

Restoration: a ‘social and ecological challenge’

Reflecting on the recent learning journey and its connection to restoration, Page underscored that coastal resilience “begins with a deeper understanding of each other and our home.” 

As Team Zostera prepares for long-term eelgrass conservation, it considers the regulatory aspects associated with ongoing stewardship. With a potential “seed” of transportation, the group is dedicated to mapping and monitoring, necessitating community engagement.

“Restoration is a social challenge,” Page said. “Success in regenerating pilot-scale beds must be accompanied by greater public awareness and a deep appreciation for the species and its significance for the economy and the environment.” 

In other words, restoration is possible, but it requires long-term support and political will. 

Another complicating factor is that eelgrass meadows vary significantly from year to year and across different locations — factors such as temperature, light, depth and sediment characteristics all influence site variability.

There is no silver bullet solution, as eelgrass decline differs case by case. However, the prevailing theory is that green crabs are to blame. As they search for food, they damage eelgrass beds, further complicating the ecosystem’s health.

Northern Casco Bay, particularly Maquoit Bay, is known for its mud flats that become exposed at low tide. Such areas, sheltered from wave energy and home to abundant prey, create ideal habitats for green crabs. As a result, they have witnessed significant loss of eelgrass.

“In Massachusetts, scientists have chalked up eelgrass decline to water quality issues,” Goeke said. “It’s not as easy to stake that claim here in Maine.” 

If green crabs are such a nuisance, what can be done about them? 

Goeke noted that the Maine Sea Grant is researching ways to utilize green crabs, including the best time to harvest them for a soft-shell fishery. This spring, trucks filled with critters were delivered to Cambodian immigrants at the Khmer Festival, where green crabs were served as a cultural delicacy.

Composting green crabs is another possibility, but no one has invested in this opportunity.

‘Now, we wait’

With seeds cast, the DEP will take the helm and sporadically monitor growth. The goal is to detect early germination in the spring, but it’s a slow process, so Team Zostera doesn’t anticipate being able to call the project a “success” until October 2025. 

“Fingers crossed for no crazy winter storms,” Goeke said. “Now, we wait.” 

Understanding how an eelgrass shoot grows over a year and which method — staked teabags or hand-casting — yields greater results will inform the group’s next steps. 

“Establishing even a small patch requires significant effort,” Bogg said after surfacing from her 48-minute dive. Underwater she saw hermit, flounder and pesky green crabs near the restoration site. “Hopefully, we gather valuable data from this experience so that we can expand our efforts.” 

As the decline of eelgrass becomes a more pressing issue, Goeke aims to organize a summit with project partners and other scientists to consolidate findings and better understand future trends. 

“The focus of this year’s summit is to gather insights from summer projects and contextualize the work being done at large in the field,” Goeke said. “Next year, we hope to hold a more public-facing summit with local community members.” 

In the meantime, as the seeds mature, Dutton will lead subsequent germination studies. She will test the viability of eelgrass under various conditions using a tetrazolium assay, crush test, fall test and direct testing by manipulating temperature and salinity in Petri dishes.

“If there is a takeaway, may it be in the approach,” Goeke said. “Community-engaged projects tend to be more successful. People must recognize the significance of this work. This species is disappearing and its protection demands teamwork.”

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