Efforts to reduce the impact of increased ocean acidification are being examined for the waterways around Long Island and New York City as increases in carbon dioxide change the chemical makeup of bays, coves and creeks and threaten rebounding shellfish populations.
New York’s Ocean Acidification Task Force held one of its regularly scheduled meetings at Stony Brook University last week as the 14-member commission works to finalize a report that will outline ways to address the problem for New York.
Oceans absorb around 30 percent of the carbon dioxide that enters the atmosphere from all sources, according to the National Oceanic and Atmospheric Administration. But as CO2 levels rise globally from man-made sources, more is entering waterways than ever before. Chemical reactions triggered by the increased carbon cause seawater to become more acidic. At the same time carbonate ions, which are crucial to the calcification process for shellfish and corals and plankton, become more scarce.
For Long Island, which has a thriving shellfish industry, acidification poses a bigger threat to bays, coves and creeks than to the ocean, where it can interfere with mollusks shell production and may also impact finfish, scientists say.
“It’s more a problem in our localized waterways, in our creeks and coves, where you have the combination of high temperatures and acidification,” said Chris Pickerell, marine program director of the Cornell Cooperative Extension and a task force member. The cascading impact to local bays is something “we’re more concerned about,” because it’s “more drastic and more dramatic than what we’re seeing in the ocean itself.”
Pickerell said documented impacts of acidification’s effect locally are just beginning to the recorded.
“We think we had ocean acidification issues causing die-off of young clams,” he said. “We were able to move our source of water to the bay rather than the creek and get around that. But it’s something we have to think about.”
Larger-scale measures to counteract acidification are already being examined by the task force. In January, Frank Roethel, an adjunct professor at Stony Brook University’s School of Marine and Atmospheric Sciences, told the group of techniques already in use to lower acid level in lakes, including the introduction of chemical lime, that could translate to marine ecosystems, though not much has been published to specifically address those larger, less static waterways, according to his presentation.
Highly alkaline solids or liquids could be introduced into sewer treatment facilities or saltwater-cooled power plants, which send large amounts of water back into the ocean, bays and the Long Island Sound.
Addressing carbon production is another mitigating measure. Using recycled glass in the production of cement, which contributes to around 7% of the world’s CO2 emissions, could help alleviate two problems at once. New York uses 3 million tons of Portland Cement annually, and each ton produces a ton of C02 emissions, Roethel reported.
Ground-up clam, oyster and scallop shells could be a cost-effective way to reduce acidity in a method that has “no adverse effects,” according to his presentation.
Then there’s sea grass.
Brad Peterson, an ecologist and associate professor of Marine and Atmospheric Sciences at Stony Brook University, said his studies of seagrass in waterways from Long Island Sound to Shinnecock Bay have already shown favorable changes in the pH of the water as oxygen levels increase.
Large patches of seagrass in waterways can create “sanctuaries from ocean acidification,” Peterson said. Local seagrasses such as eel grass are rooted, produce seeds and completely submerged. Their high photosynthetic levels make them good candidates for drawing CO2 out of the ocean. They are also “really important habitats for juvenile shellfish,” which can be affected more than other species by ocean acidification.
Researchers are not directly attributing increased acidification to the catastrophic die-off of adult Peconic Bay scallops this fall, a phenomenon Pickerell and Peterson believe was the result of high water temperatures in July at the height of the spawning season. But fellow researcher Christopher Gobler, professor at the Stony Brook School of Marine and Atmospheric Sciences, said at a conference on Friday that scallops are "much more sensitive" to increased CO2 levels and increased acidification than other mollusks, though specific pH data isn't available for this year to show a direct link.
That’s not to say that increases in acidification won’t eventually impact scallops and other shellfish.
“It’s not to that point yet, here, what we’re seeing it on the West Coast, but it can happen in a short period of time,” he said. “In the next decade, the next couple of decades, we can have meaningful impacts to the shellfish population and, potentially, recruitment of any of the shellfish species.”