Artificial Reef

Concrete reef ball in the Chesapeake Bay provides a breeding ground for oysters and attracts fish, crabs, and other sea life. Photograph by Michael Eversmier

The art and science of shellfish restoration in the Providence River


By Mary Grady


AT INDIA POINT PARK IN PROVIDENCE, DESPITE THE PICTURESQUE views of the bay, boats, and birds, it’s easy to see that nature has taken a pounding from the last few centuries of humanity. The shallow waters along the shore are spiked with the ragged remains of ancient piers and shipwrecks, and the shoreline itself, once carpeted with resilient reeds and grasses, now is hardened with cement walls and piles of jagged rock. These intertidal waters have absorbed centuries worth of detritus and debris from an industrialized urban watershed, from toxic metals to sewage waste to freeway runoff. The fish, oysters, and mussels that once flourished here have been gone since long before the memory of anyone visiting today.

But the park, and the Providence River it overlooks, are on the verge of a new era. Huge infrastructure projects, years in the making, now divert most of the raw sewage that for decades ran into the river from a network of overflow pipes. The water already is noticeably clearer, less murky and stinky, and fish are coming back. And soon, a little cove nestled into the park’s shoreline will become the site of an experimental artificial reef that aims to restore shellfish to the river—not as a market crop or a source of subsistence, but as a mechanism to help purify the water.

Shellfish are filter feeders, pumping up to 50 gallons of water per day through their digestive systems. They feast on the phytoplank- ton that are fed by excess nutrients in the water, such as nitrogen and phosphorus, that seep into the river from lawns, cesspools, and runoff, and rob the river of oxygen.

Finding a way to bring shellfish back to the river at the edge of such a busy urban park has proved to be a challenging task. The effort has brought together artists and scientists from a range of disciplines, and expanded from the academic world into the realm of government regulators, park advocates, and local school kids.

Students working on a project at the Rhode Island School of Design began their study of shellfish several years ago, when Marta Gomez-Chiarri, a professor of fisheries at the University of Rhode Island, spent a semester at RISD as a scientist-in-residence.

“I got involved in various efforts about how to use art and design to communicate science,” Gomez-Chiarri recalls. “There was a studio collaboration between faculty in sculpture, landscape architecture, and myself, in which students looked at issues related to shellfish restoration. As part of that, students came up with a few very interesting projects using sculpture, design, and landscape architecture to create habitat.”

The students experimented in the lab with a variety of forms and materials to see what kind of structures they could build that would be practical and effective in providing habitat for shellfish like oysters and mussels. To figure that out, they first had to understand the biology and lifecycle of the shellfish. They learned that the only time oysters and mussels are in motion and searching for a place to stay is in the larval stage. Once they find a spot, they settle onto it, hold tight, and stay put.

The project evolved into a collaboration involving students and faculty from RISD, URI, Roger Williams University, and Rhode Island College, with support from RI-EPSCoR, the Rhode Island Experimental Program to Stimulate Competitive Research, funded by the National Science Foundation.

The students’ research produced a trio of designs that will be tested in a pilot project. Platters made of crushed concrete and oyster shells are arrayed in a variety of shapes, sizes, and configurations, and affixed to complex structures that mimic the function of natural reefs. Three of each design will be built and anchored in the waters off the park, and local college and grade-school students will observe them on a regular basis to collect data about their effectiveness and their impact on the ecosystem.

The concept of restoring shellfish populations to help clean urban waterways is relatively new in Rhode Island, but it’s already been tried in other places. Peter Malinowski, director of the New York Harbor Foundation’s Billion Oyster Project, working with local school kids, hopes to restore a billion oysters to New York’s coastal waters.

“We’ve put 16 and a half million oysters in the water so far, and we’ve restored over an acre of reef, using metal structures designed and built by students,” Malinowski said in a cellphone call from the field in the fall. “We plan to have 20 acres of reef by 2020, and 200 acres and a billion oysters by 2035. It will still be a tiny little drop in the bucket, compared to what used to be here, when there were hundreds of thousands of acres of oyster reef.”

Malinowski says he has compiled data that show small improvements in the quality of the waters close to the reefs, and dramatic changes in the quality of the habitat. “When you put any kind of structure in the water, you get an immediate increase in the abundance and diversity of life around that structure,” Malinowski says. But he sees another impact from the project that he thinks is just as important as those physical changes.

“In New York, there are very few places where people can walk down to the water’s edge,” he says. “Every time it rains, hundreds of millions of gallons of untreated waste drain into the harbor. But New Yorkers aren’t up in arms about it because they don’t really notice it.” Malinowski believes public engagement is key to seeing water-quality improvements in the future. The oyster project is one way to get people to interact with the coastal waters, and once they get to know the ecosystem and see the impacts of pollution, Malinowski hopes they will be inspired to take action and lobby for change.

At India Point Park, Rhode Islanders have that access to the shore that Malinowski believes is so crucial. The designers of the artificial reef consider public outreach a key aspect of the project, so installing it in a place where a lot of people will see it was an important goal. But public visibility also raises concerns—will park visitors be tempted to try to harvest the shellfish, which aren’t safe to eat? And does the structure itself amount to a sort of visual pollution, a distraction for visitors in search of natural landscapes?

Marjorie Powning, co-chair of Friends of India Point Park, says her group has worked closely with the art and science consortium to ensure the site meets  the project’s needs for public outreach and school participation, while not interfering with the Friends’ goal to maintain a natural and uncluttered space where city residents can connect with nature. “They had a concern that really overlapped with our concerns about water quality and public education,” she says, adding that it was also important to her that the project has a small footprint, and that it’s a temporary installation with a three-year lifespan.

Warnings will be posted to discourage visitors from harvesting the shellfish, and the site has been carefully chosen so that while the reef will be visible from shore, it’s not easy to get to, having a steep rocky shoreline that should discourage casual foragers.

Nobody thinks oyster reefs can solve the bay’s water-quality problems, even if the entire bay was paved with shellfish. The main route to cleaner water is to reduce, and eventually eliminate, the pollutants that now enter the bay from treatment plants and stormwater runoff. But the reefs serve another vital function—besides their contribution to water quality—as the Billion Oyster Project has found in New York, they can provide habitat for other species.

Experiments here in Rhode Island have shown that these benefits can be substantial. John Torgan, director of Ocean and Coastal Conservation at The Nature Conservancy’s Rhode Island office, has been working for several years on a project to restore reefs at sites  in South County’s coastal ponds, using discarded oyster shells from restaurants. The shells are collected into mesh bags, then deployed across the bottoms of the ponds.

So far, the group’s preliminary data analysis has shown that the artificial reefs benefit a wide range  of species, including juvenile fish, mussels, clams, limpets, and shrimp. “It’s not just about producing more shellfish, it’s about advancing the diversity and abundance of native species,” says Torgan. “If the purpose of building artificial reefs is to improve the ecological health and function of polluted areas, it’s worth pursuing.”

 

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