Something within the water: how kelp helps Maine’s mussels increase

On a glimmering May morning, Tom Briggs pilots a 45feet aluminium barge during the waters of Casco Bay for one of the vital ultimate days of the yearly kelp harvest. Motoring previous Clapboard Island, he issues to a floating wood platform the place mussels had been seeded along ribbons of safe to eat seaweed.

“This is our most productive mussel site,” says Briggs, the farm supervisor for Bangs Island Mussels, a Portland sea farm that grows, harvests and sells masses of 1000’s of kilos of shellfish and seaweed each and every yr. “When we come here, we get the biggest, fastest-growing mussels with the thickest shells and the best quality. To my mind, unscientifically, it’s because of the kelp.”

A rising frame of science helps Briggs’s instinct. The Gulf of Maine is uniquely at risk of ocean acidification, which is able to hinder shell construction in mussels, clams, oysters and lobster, threatening an business that employs masses of other folks and generates $85m to $100m (£63m to £74m) every year.

Atmospheric carbon dioxide from fossil fuels is the principle driving force of declining ocean pH, expanding the acidity of the arena’s oceans via greater than 40% for the reason that preindustrial generation and via greater than 15% since 1985. Add carbon runoff from rising coastal communities, common inflows of chillier, extra acidic water from Canada, and intense thermal rigidity – the Gulf of Maine is warming 3 times quicker than the worldwide reasonable – and also you’re left with a mild marine ecosystem and key financial useful resource below risk.

Enter kelp. The streams of glistening, brownish-green seaweed that Bangs Island seeds on traces below frigid November skies and harvests in past due spring are a herbal solution to ocean acidification as a result of they eat carbon dioxide. Sensors positioned close to kelp traces in Casco Bay over the last decade have proven that rising seaweed adjustments water chemistry sufficient to decrease the degrees of carbon dioxide within the quick neighborhood, nourishing within reach molluscs.

“We know that, in general, for shell builders, ocean acidification is bad, and we know that kelp do better in a high-CO₂ environment,” says Susie Arnold, the senior ocean scientist on the Island Institute, a non-profit local weather and group organisation in Rockland, Maine, and a pioneer of the Bangs Island water experiments.

Working with the Bigelow Laboratory for Ocean Sciences, an unbiased Maine-based analysis organisation, Arnold and others started trying out the water off Chebeague Island in 2015 “to see if we could detect a difference between water chemistry in the middle of all that kelp and far away from it”, she says. “We planted juvenile mussels inside and outside the kelp, and we were able to show that the mussels inside the kelp had a thicker shell. Now you see Bangs Island growing kelp around their mussels because they can make a profit on kelp and also buffer the mussels.”

The CEO and co-owner of Bangs Island Mussels, Matt Moretti, studied marine biology in faculty and grad faculty, helped lift child lobsters on the New England Aquarium, and labored on an oyster farm ahead of purchasing the ocean farm together with his father in 2010. Within a yr, that they had began rising kelp along the mussels in an method referred to as built-in multi-trophic aquaculture.

“Even before we started farming mussels, I was interested in that concept as an environmentally friendly way of farming, and of farming an ecosystem rather than a single species,” Moretti says from his bare-bones upstairs place of job in Bangs Island’s warehouse at the Portland pier.

As the kelp harvest grew, Moretti realised they wanted a technique to stabilise the seaweed, which didn’t closing lengthy after it got here out of the water. For some time they dried it themselves, placing it within the warehouse and at the docks. Now, they promote all of the recent seaweed catch to an area processor, which turns it into fermented meals corresponding to kimchi, amongst different merchandise.

“We always suspected that there was this positive interaction between the mussels and kelp, and we suspected that because kelp photosynthesises, it sucks carbon out of the water, then therefore it must be good for the ocean and good for the mussels,” Moretti says. Bigelow’s water trying out has confirmed that “we’re having a positive impact”.

Nichole Price, the director of Bigelow’s Centre for Seafood Solutions, collaborated with Arnold on the ones early experiments and continues to watch the water round Bangs Island mussel and kelp traces, an effort that has expanded to incorporate water tracking at seaweed farms from Alaska to Norway. In a paper printed this yr within the magazine Nature Climate Change, Price, Arnold, and a bunch of co-authors documented but otherwise by which seaweed farms can give a contribution to the well being of the arena’s oceans: via trapping carbon on the backside of the ocean.

“When you harvest, you’re not pulling up every last bit of seaweed,” Price says. “We’ve been diving under farms during harvest, and you can see the bits and pieces that rain down. Then there’s a culling process, the bits and pieces that get tossed over, and that’s what this paper has measured: the unusable, unsellable parts of the harvest that end up on the sea floor.”