New England Without Clam Chowder?

Dr. Hauke Kite-Powell, Woods Hole Oceanographic Institution

It’s hard to envision, standing by the shore, but the chemistry and temperature of the ocean is changing in fundamental ways — and the shellfish we love to eat are at risk. If we don’t begin to take action, our fishermen soon may have a much harder time harvesting clams, oysters, scallops, mussels, and lobsters.

Last month, coastlines throughout New England were closed to shellfish harvesting because of a marine phytoplankton bloom that produced dangerous levels of a toxin that accumulates in shellfish and is harmful to humans. At the same time, high levels of another organism — a virus that can cause severe gastroenteritis in humans — closed oyster beds on Cape Cod.

There is growing concern that incidents like these will become more frequent around the globe as human activity disrupts the delicate balance of seawater conditions supporting ocean life. Among these changes are rising temperatures in the atmosphere and ocean and falling seawater pH, or “ocean acidification.”

Ocean acidification has two main causes: First, the ocean absorbs about one-third of the carbon dioxide generated by burning fossil fuels. That carbon dioxide combines with seawater to produce an acid, lowering the pH of seawater and making it difficult for shellfish to build their shells and grow.

Second, coastal development is flushing more nutrients from septic tanks and lawns into near-shore waters, fertilizing blooms of marine plant life. When those plants die and decompose, they deplete the seawater of oxygen and produce even more carbon dioxide that further lowers the pH of coastal waters.

This isn’t a Chicken-Little scenario. In 2005, naturally occurring upwelling along the Pacific Northwest lowered the pH of coastal waters and led to massive die-offs of oyster larvae in Puget Sound hatcheries. This and forced the region’s multimillion-dollar shellfish industry to shut down and modify or relocate operations — an indication of what could be in store for us if human activity causes similar changes in coastal ocean water conditions to become the norm.

We’re probably not going to find a magic-bullet solution to neutralize these problems instantly. So we need to unravel the factors that will determine future changes in seawater chemistry and the potential impacts on marine organisms throughout the marine food web — and use that information to find ways to adapt to the changes.

We should pay attention to the signs we’ve already glimpsed and get ahead of these changes before they cause trouble for public health and seafood industries.

Dr. Hauke Kite-Powell’s research at the Woods Hole Oceanographic Institution focuses on public and private sector management issues for marine resources and the economic activities that depend on them.