Lobsters and acidic seas: can shellfish help neutralise one of the greatest threats to the ocean?

For many in the US region of New England, the lobster roll is synonymous with summertime. Loaded into a toasted bun, chunks of the sweet meat are served hot and soaked in butter, or chilled and slathered in mayonnaise with celery and herbs.

The only thing more debated than the recipe is the price: the once-humble roll now routinely fetches $30 (£22), or even $50, in a sign of the changing times – and seas.

A third-generation lobster fisherman, Scott Lord spends his days hauling traps on the Gulf of Maine, which is warming faster than 99% of the world’s oceans. “Whether you agree with who says why it’s happening, it is happening,” he says.

Bycatch that was once plentiful, such as sea urchins, sand dollars or starfish, are increasingly rare. And, most concerning, Lord has noticed the number of inshore lobsters dropping dramatically over the past 15 years, pushing fishers farther and farther offshore.

Motivated to find a remedy, Lord joined a regional shellfish committee. “Why are there not clams where there used to be clams? Why are they not coming back, no matter what we do?” he asks.

Hundreds of miles to the south in Massachusetts, on a sandy crook of land that spins out to form Cape Cod, Adam Subhas, a scientist at the Woods Hole Oceanographic Institution, is trying to find the answers.

• Scott Lord brings in his catch of lobster to the wharf in Tenants Harbor, Maine

• Scott Lord brings in his catch of lobsters from traps off the coast; he has had to go out farther from shore to find the shellfish in recent years. Lobster rolls at the Lobster Trap Restaurant & Fish Market in Bourne, Massachusetts

Subhas heads LOC-NESS (Locking Ocean Carbon in the North-east Shelf and Slope, an initiative researching how to decarbonise the ocean, also known as marine carbon dioxide removal (mCDR). Scientists working in this field are trying to discover whether the ocean, which is estimated to absorb about 31% of atmospheric carbon, could be manipulated to soak up even more.

Proponents say ocean carbon removal could help stop the world from passing the 2C (3.6F) tipping point outlined in the 2016 Paris Agreement, if used in conjunction with the reduction of fossil fuels.

What was once a small-scale idea is rapidly gaining traction. A database newly launched by the Pulitzer Center, Ocean Carbon Removal Watch, which tracks mCDR investments, field trials and research, shows that more than £370m has been invested in the sector over the past five years.

This was initially driven by the private sector but, thanks to a spate of US federal investments in 2023 – totalling at least £44m, according to a Guardian analysis of the database – scientific field trials began to catch up. Until, that is, President Trump announced sweeping cuts to all federally funded ocean sciences.

• Adam Subhas, who is heading the LOC-NESS programme, among lobster larvae at the Woods Hole Oceanographic Institution laboratory in Massachusetts

• Adam Subhas with a tiny lobster at Woods Hole, with food being prepared for the lobsters

“The funding cuts are affecting everyone,” says Subhas.

With federal science backing nearly dried up, LOC-NESS is the last “unicorn” for US ocean carbon removal.

It is testing the technique that has garnered the most support in the past few years: ocean alkalinity enhancement (OAE). Its central tenet is to encourage seawater to absorb more atmospheric carbon by dispersing alkaline materials over a wide area of ocean.

Working 40 miles offshore from Boston in the Gulf of Maine’s Wilkinson basin last summer, Subhas’s team put about 65,000 litres of sodium hydroxide into the sea. The highly alkaline material was mixed with a red dye to make it easier for sensors and satellites to track.

• Subhas, left, and Kate Morkeski prepare to cast a net to pick up plankton off their research vessel during ocean alkalinity enhancement field trials

“The ocean is 70% of the Earth’s surface and, if this is really going to scale [up], we have to understand how this might work in the open ocean, too,” says Subhas, who has a Loch Ness monster soft toy perched on a shelf in his laboratory next to the scientists’ bible, the CRC Handbook of Chemistry and Physics.

The team used a fleet of boats and monitored alkalinity and carbon uptake for four days via autonomous underwater vehicles that provided highly sensitive measurements.

“For a while, there’s been scientific debate around if you could even measure some of these signals,” says Subhas, who presented his findings at this year’s Ocean Sciences Meeting. He believes they can provide a roadmap for how alkalinity enhancement can be measured and modelled in the future.

• Three ships took part in the LOC-NESS Project’s successful OAE trial in the Gulf of Maine, which included observers from the US Environmental Protection Agency, the Massachusetts state fisheries body, the National Oceanic and Atmospheric Administration and the fishing industry

• Adam Subhas, right, and Jennie Rheuban take samples from a CTD probe, which collects samples allowing scientists to measure the temperature, salinity, oxygen and acidity of seawater at different depths. Right, an autonomous glider with sensors to measure the alkalinity of the sea

“We need to be really clear about the need for large-scale emissions reductions, while at the same time figuring out the science behind some of these more novel approaches that might help supplement those large-scale reductions into the future,” says Subhas.

Outside the Woods Hole laboratories, the thrum of alkaline water being pumped into machines analysing dissolved inorganic carbon plays in the background.

Lobsters and alkalinity

Based on data collected last summer, the team is examining two years of trials to understand how marine creatures respond to different levels of alkalinity. After initial biological studies on species at the base of the food web such as phytoplankton, the team is now focusing on lobsters.

It is a species that generates the second-highest value of any seafood landed in the US, accounting for just under $700m (about £550m) in 2023. Then they will move on to the tautog wrasse, a popular species for sports fishing.

Designing the experiment came with its own challenges. Lobsters are very sensitive during moulting, do not like temperatures above 20C (68F) and “unfortunately, they eat each other, given the opportunity”, says Chris Murray, a marine biologist who built special floating mesh cups to avoid cannibalism.

• Chloe Dean, a researcher, assesses the biological impacts of higher alkalinity. Preliminary lab results showed no increased mortality or behavioural changes after exposure to elevated pH and alkalinity

So far, Murray and his team have not seen any lethal effects with either low or high levels of alkalinity, but they will analyse the lobsters’ RNA, the molecular building block for all cellular functions, at the end of the trials to better understandtheir physiological response and, in particular, their ability to secrete waste.

Describing these studies as the “tip of the iceberg”, Murray says the next step of this experimentation would involve creating a mini-ecosystem featuring many marine species.

“We need to do this research,” he says. “It’s really important to weigh these impacts against what is predicted to occur in the ocean. We know that ocean warming is going to be a major disruptive force to marine food webs.”

Can European funding save the day?

Luckily for the researchers, there is still a glimmer of hope from across the Atlantic. Just as US funding was abruptly stopped, Europe began scaling up its academic grants to study removal of marine carbon dioxide.

According to analysis of the Ocean Carbon Renewal Watch data, the European Union disbursed more than £8.5m in grants in the past two years, which has distributed funds to more than 20 universities across Britain and the rest of Europe.

At the University of Gothenburg, Sam Dupont, a senior lecturer who studies the effects of ocean acidification and warming on marine ecosystems, was buoyed up by this newstream of funding.

Studying alkalinity thresholds of sea urchins, mussels and fish eggs, he is beginning two years of experimentation in Sweden and Iceland, where he is working with the country’s Marine and Freshwater Research Institute to see how alkalinity affects the same species in different bodies of water.

“We want to cover a bunch of different creatures,” he says. “We see that if you go too high in alkalinity, there’s something going wrong in their physiology and they develop abnormally and die.”

• An underwater glider with Amanda Pinson, of the Woods Hole marine chemistry and geochemistry department, and Patrick Deane, an engineer in the physical oceanography department

Dupont is concerned that private industry is starting to attract finance for large-scale experiments by issuing ocean carbon removal credits. Commercial scale is “ready to jump, but we don’t understand how it [OAE] is going to impact biology yet”, he says.

“The equivalent would be: you smoke a cigarette and you go to the doctor the next day and say, ‘There is no effect on cancer’,” says Dupont, who estimates that it will be about a decade before scientists can accurately state what the safe alkalinity thresholds are for marine life.

Back at Woods Hole, a few buildings over from Subhas, Ken Buesseler, a professor emeritus of marine radiochemistry, has experienced the US science funding cliff first-hand. He has spent three decades studying iron fertilisation – which adds iron to the ocean to encourage plankton growth, thereby sequestering carbon. That is, until his US Department of Energy (DoE) grant was stopped halfway through last year with, he says, only about half of the $5m promised being paid out.

Researchers were to hear about a new phase of funding last winter, but “none of those came through”, says Buesseler. “There is no pipeline in DoE for carbon management any more.”

Buesseler also leads an ambitious project called Ex-OIS, which is in the early stages of seeking permission to study iron fertilisation across more than 400 miles offshore of Alaska’s coast. It would be the first venture ever to have gone through national and international regulatory processes.

But with little to no funding opportunities in the US, it is hard to imagine it attracting the $30m needed to launch the experiment in 2028.

“I feel like we are just kicking the can,” says Buesseler, who believes that these geoengineering techniques need to be used in conjunction with fossil fuel reduction.

“The climate crisis isn’t going away because we stop funding research into ocean solutions, so the problem will be with us. It is getting harder and harder to address.”

This story was produced in partnership with the Pulitzer Center and with support from an Alicia Patterson Fellowship