Shoals class experiment analyzes seaweed harvested for cosmetics and cattle food

Media Contact

John Carberry

As part of a year-long experiment on Appledore Island, six miles off the southern Maine coast, students and instructors cut rockweed, a brown seaweed (Ascophyllum nodosum) that anchors to the rocks where the ocean meets the island. Some strands were shorn at their holdfasts on the rocks, others were cut at 16 inches, and yet others were left to grow as controls.

The experiment is part of a class, Introduction to Marine Conservation Biology, running July 19-Aug. 2 at Shoals Marine Lab, an undergraduate teaching facility on Appledore Island administered by Cornell and the University of New Hampshire. The experiment has real-world implications, as controversy rages elsewhere in Maine over the impacts of removing commercial quantities (nearly 12 million pounds in 2008) of rockweed for processing into cosmetics, color enhancement in red meat, dog biscuits and sheep and cattle feed. This seaweed harvest is expanding throughout the coast of Maine, perhaps eventually threatening shores at the Isles of Shoals.

The thick rockweed, used in small amounts for traditional New England clambakes, blankets the coastal rocks in New England and serves as an essential intertidal habitat for more than 60 species, including crabs, mussels, snails, amphipods (small crustaceans consumed by ducks), juvenile pollock and other fishes.

After measuring the seaweed, the instructors will use the results to assess how long it might take a rockweed community to restore itself after a cutting and how one might define sustainable harvesting.

"We have never seen a seaweed harvester out here, but over the last decade the global demand has gone up and up," said Robin Hadlock Seeley, senior research associate and an assistant director at the Shoals lab, who teaches the course with Hal Weeks, assistant director for island and coastal programs at the lab, and Willy Bemis, Shoals Marine Lab director and professor.

Seeley helped expand regulations for rockweed harvesting in Cobscook Bay, at the other end of the Maine coast, where companies have been cutting rockweed since 2007. Now, companies are restricted to taking less than 17 percent of rockweed biomass in Cobscook Bay, because bycatch (unintended harvesting of other species with the seaweed) is also a problem in the harvest. Still, there are no regulations on how much rockweed can be taken by harvesters outside of Cobscook Bay, which is a concern since "[harvest companies] plan to expand the harvest down the rest of the Maine coast," she said.

Rockweed grows about 8 inches every two and a half to three years and has a main stem with side branches coming off of it. Initial measurements of the cut rockweed this summer revealed that when strands were cut close to the holdfast against the rock, the plant did not grow back. When cut to 16 inches -- which is the regulation height for rockweed cut in Maine -- the main shoot did not grow beyond the cut, but the uncut side shoots continued to grow. However, "harvesters don't always cut to the regulations," Seeley said.

"Resource managers and conservationists are always debating whether a natural resource harvest is sustainable or not," she said. "Is this rockweed harvest sustainable?" she asked her students. "How would you define 'sustainable harvest' in a species that also serves as habitat for 60 other species?"

The four-credit course, which includes 11 students this summer, seeks to integrate principles of marine biology and ecology with case studies of successes and failures in resource harvest management, address science behind conservation practices, and consider changes in marine governance that may hold promise for progress toward sustainability.


Story Contacts

Krishna Ramanujan