The question of ocean acidification

Unprecedented floods that swamp cars and damage homes; dangerous storm surges that batter coastal roads and smash seawalls. We can already see the dramatic effects of climate change in the Northeast. But even on the clearest and calmest of days, a change is brewing in our world’s oceans that could have worse and more destructive consequences for local industries and livelihoods.

Oceans are warming and acidifying. Warming seawater has already caused economic damages such as periodic closures of Dungeness crab fishing. Ocean acidification is starting to take a toll. And the long-term effects of this change could be ruinous for marine life worldwide, and the people who depend on it for their food and income. Will ocean acidification hurt stocks in the Gulf of Maine, where the fishing industry nets hundreds of millions of dollars annually? If acidifying waters contribute to the decline of marine life in the region, can we slow the decline? Who is responsible for the damages—and can they be made to pay?

What’s Happening Globally
While some emissions from burning fossil fuels are taken up by plants and animals on land, some linger in the atmosphere, contributing to the blanketing “greenhouse” effect that warms the earth. The world’s oceans absorb the rest, nudging its chemistry along the pH scale from basic toward acidic. Ocean surface waters are now, on average, nearly 30 percent more acidic today than they were in 1850. And ocean acidification is now happening at a faster rate than at any point in the last 66 million years. Projections show that if we do not reduce our carbon emissions, average ocean surface waters could be more than twice as acidic in 2100 as they were in 2000.

The consequences of acidification are disastrous to marine life. As carbon dioxide dissolves into the ocean, chemical reactions deprive shell-forming marine organisms such as crabs, corals, and foraminifera of the carbonate ions they need to build their protective shells. Studies done on commercially caught crab species in Alaska have found that crab survival rates drop consistently with more acidic waters. Coral reefs bleached by warming waters are less capable of rebuilding as their environment becomes more acidic. And populations of tiny foraminifera—an important food source for many species—risk a sharp decline, threatening the entire global food chain.

“Within the next decades, we’re fast approaching a threshold where particular organisms can’t form shells and deep-water corals can’t bounce back,” says Brenda Ekwurzel, director of climate science at environmental advocacy nonprofit the Union of Concerned Scientists.

What’s (Not Yet) Happening Locally
The Gulf of Maine is among the fastest-warming regions of the world’s oceans. For now, the drastic warming is associated with changes to ranges of key fisheries species in the region. Experts are monitoring of the potential effects of the accompanying increase in salinity and ocean acidification on shellfish and fisheries yields. According to Joe Salisbury, a research associate professor in earth sciences at the University of New Hampshire, it’s different on the West Coast.

“Oyster hatcheries in the US Northwest were the first to see the effects of ocean acidification on their stocks. They’ve had to take steps to reduce the damage,” Salisbury says. “But the effects of ocean acidification are being somewhat mitigated, or muted, in this region.”

However, he says, so long as emissions continue to increase, the changing pH of the world’s oceans will catch up with Gulf of Maine waters.

“Ocean acidification will prevail in the end,” says Salisbury, who also serves on the steering committee of the Northeast Coastal Acidification Network (NECAN), a group of scientists, resource managers, and marine industry partners who support research into the effects of acidification.

“It might be in 50 years, it might be in 100 years, but it’s not going to go away,” he says. “Fishing communities understand it’s a clear threat, and they want to know how it will affect their bottom line. We’re working on understanding how and when these impacts will be felt.”

Trying to Get Ahead of Acidification

At Mook Sea Farms in Walpole, ME, Head of Research and Development Meredith White is well aware of the impending danger of acidification on the oysters she helps cultivate in the Damariscotta River. While mature oysters are thriving in the warmer waters, she says, larval and juvenile oyster production at the hatchery has already been negatively affected by ocean acidification. As a result, larval and juvenile oysters are now raised in buffered waters in the farm’s hatchery, where they can grow their shells in ideal conditions. And White and company owner Bill Mook are participating in multiple studies with different regional institutions—including NECAN—to help track the effects of ocean acidification on their oysters.

“Understanding how all of this works, and how it will progress as ocean acidification continues, is a big priority for us,” says Mook. “This is why we are conducting our own field-based experiments and urging others to do the same.”

White agrees. “It’s important to have a better understanding of how specifically juvenile and market oysters are affected by ocean acidification. It will be helpful to have field-based scientific research to know how bad the problem will be.”

Pamela Worth, Fishermen’s Voice, August 2019. Article.

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