Reef Balls, Real Impact: Living Shoreline Project Restores the Thames River

Along the banks of the Thames River in New London, lines of dome-shaped reef balls now shelter schools of fish, stabilize the shoreline, and bring new life to an area once threatened by erosion. What began as a small pilot in 2021 has grown into a thriving example of how science and community partnerships can protect the health of Long Island Sound.

Led by Maria Rosa, Associate Professor of Biology at Connecticut College, the project, supported in part by the Long Island Sound Futures Fund, uses reef balls – concrete domes created by the Reef Ball Foundation that mimic natural reefs – to protect shorelines while creating new habitat for marine life.

Building a Living Shoreline

The Thames River, Connecticut’s third largest river, runs along the edge of Connecticut College’s campus before flowing into Long Island Sound. It’s a busy waterway that supports naval operations, shipbuilding, and commercial traffic and it has been continuously dredged since the 1800s. Combined with sea-level rise and stronger storms, those pressures have left its shorelines, including the College’s waterfront, vulnerable to erosion.

Recognizing the need to protect both the campus shoreline and the river’s natural habitat, Rosa began searching for sustainable solutions. She first considered re-introducing an oyster reef, but after learning the project would not be permittable at this site, she turned to reef balls, a nature-based approach known as a living shoreline. Unlike seawalls or jetties, which block waves but also prevent natural sediment movement, living shorelines work with nature. The reef balls help slow waves, trap sediment, and provide shelter for fish and other marine life, allowing the shoreline to rebuild over time.

The first phase of the project, launched in 2021 with support from Kenny Chesney’s No Shoes Reefs initiative, installed 30 reef balls protecting about 35 linear feet of shoreline. Rosa and her students named the site Camels Reef, after the Connecticut College mascot. With additional funding in 2023, the project expanded to include 350 more reef balls, protecting 200 linear feet of shoreline and more than 1,200 square feet of habitat.

Within the first year, the team saw signs of success that most projects wouldn’t expect for five to ten years: sediment began to accumulate and new species appeared. At the start of the project in 2019, Rosa documented just five species at the site. By 2023, there were more than 30, including larval animals suggesting the reef was serving as a nursery ground. This fall for example, juvenile oyster toadfish and other larval fish were found in the reef for the first time, following records of adults of the same species from the past year.

The sediment has also changed dramatically. Rosa’s team measured an average of three centimeters of new soil, with some areas gaining up to five. “We’re seeing both terrestrial and marine sediment being added to the reef,” she said. “It’s enough to begin planting.”

This fall, Rosa and her students planted 1,000 plugs of smooth cordgrass (Spartina alterniflora), a native marsh plant, and plan to plant another 1,000 in the spring to help jump-start marsh formation. While the reef balls themselves provide habitat and help trap sediment, the true measure of the project’s success will be the growth of healthy marsh. A thriving marsh acts as a natural buffer, diffusing wave energy and reducing erosion, while also supporting greater biodiversity. Next summer they also plan to conduct a comprehensive biodiversity survey to document how species diversity and abundance have changed five years into the project.

Nature Thrives — and So Do Students

Rosa says one of the most exciting aspects of the project has been watching the site come alive. Bald eagles, mink, osprey, seals, blue crabs, and striped bass have all been spotted near the reef. “The difference between our reef site and the downstream control site is striking,” she said. “The sediment, the biodiversity—it’s a whole different environment.”

Students and volunteers have been involved in every step of the process, from building and deploying reef balls (each weighing hundreds of pounds) to planting grasses and conducting monitoring surveys. “Seeing the impact of their work firsthand motivates them to keep coming back,” Rosa said.

A Ripple Effect for Long Island Sound

The Thames River is a major tributary to Long Island Sound, carrying freshwater, sediment, and nutrients downstream. Healthy shoreline habitats here have far-reaching benefits for the Sound’s ecosystem, providing nursery grounds for fish, filtering pollutants, and buffering against erosion.

Projects like Camels Reef directly support the Long Island Sound Partnership’s goals of clean water, thriving habitats and abundant wildlife, resilient communities, and an informed public. As the reef grows, it helps improve water quality, trap excess nutrients, and build resilience to sea-level rise and storm surge – all while serving as a hands-on learning site for students and volunteers.

Lessons Learned and Looking Ahead

Rosa admits the project wasn’t easy to get off the ground. “When I first started, people told me it wouldn’t work,” she said. “But I thought, if you build the habitat, the species will come—and they have.”

From her initial vision of an oyster reef to today’s thriving living shoreline, Rosa sees success not just in the ecological results, but in the engagement the project inspires. “This wouldn’t have been possible without our students and volunteers,” she said. “Their work has made a real difference.”

Looking ahead, Rosa hopes to expand the reef even further, potentially adding another 200 linear feet of reef balls to extend protection toward the mouth of the Thames River. That will require new permits and careful design to match the varying shoreline slopes and habitats along the river, but Rosa is confident in the project’s future.

“This is just the beginning,” she said. “We’re building something that protects our campus, supports wildlife, and strengthens Long Island Sound for years to come.”

Visitors explore the Camels Reef site, where an “Experiment in Progress” sign highlights the ongoing research and monitoring behind this living shoreline project. Photo by Erica Casper/CT Sea Grant.