Brian Helmuth in News@Northeastern: When a Heatwave Comes, This Scientist Takes a Shellfish’s Perspective | Global Resilience Institute

NAHANT, MASS. — Stepping into the gap between the rocks, it’s easy to understand what Brian Helmuth is talking about.

The summer sun beats down, and the rocky shore surrounding Northeastern’s Marine Science Center is toasty. But in this crevice, the marine biologist is partially shaded from the midday rays, and his feet are submerged in the shallow sea water that remains here when the tide goes out. It’s noticeably cooler and more comfortable.

And so are the creatures that Helmuth studies. Mussels fill the corners of the shallow pool, a crab darts over seaweed, snails cling to the submerged rocks, and barnacles mark a distinct high-water line on the walls of the small coastal canyon. It’s a safe haven for the sea creatures, shaded a bit from the heat of the summer sun and kept cool by the water that collects here.

But when Helmuth steps out of this sanctuary, just a few steps from its entrance, he exclaims, “Everything is dead.”

As severe heat waves are becoming more frequent and more intense in many parts of the world, coastal researchers are increasingly finding the cooked carcasses of creatures that make a living in the part of the shore where the tides cyclically expose and quench the landscape, called the intertidal zone. In fact, during the recent record-setting heat waves in the Pacific Northwest region of the United States and western Canada, millions of shellfish got so hot that they cooked right on the rocks where they’d previously thrived.

That’s what Helmuth thinks happened to the barnacles whose eulogy he proclaimed without ceremony outside the cooler, more lively crevice ecosystem in Massachusetts. They probably cooked during a heat wave in 2020, he says, because a few smaller, likely younger barnacles are still alive among the empty shells of the larger ones.

Helmuth, a professor of marine and environmental sciences at Northeastern, is searching for the places—however small—where the coastal creatures don’t cook in their shells when an unprecedented heat wave sweeps through the region. Those areas of refuge (called refugia by scientists) might be a place where these species can survive through a hotter future.

“We don’t care, per se, that that barnacle lives and that barnacle dies,” Helmuth says, pointing to two individual crustaceans dotting the dark rock. “But what we care about is, ‘Does this site collectively have enough of those refugia that it can still support populations after a heat wave?’”

The idea is that if enough animals make their homes in nooks and crannies that are buffered from intense heat waves, they can reproduce and replenish the populations that don’t survive. If scientists can identify those places, then conservationists can tailor their efforts to protect those places—or even make more such safe havens when building seawalls or other coastal infrastructure.

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