Some Like It Hot

Native oysters offer hope in a warming climate

It’s easy to assume that as the climate warms, marine life will suffer. But new research led by the Elkhorn Slough Reserve suggests that some might actually stand to benefit, at least in the short term, and that includes the Olympia oyster, a tough little native of West Coast estuaries. Turns out they like it hot.

Together with more than 100 partners in the Native Olympia Oyster Collaborative (NOOC), Reserve scientists from Elkhorn Slough, Tijuana River, San Francisco Bay, South Slough, and Padilla Bay looked at where Olympia oysters live across their entire range—from British Columbia to Baja California. The goal? Understand how air temperature limits where they thrive in the intertidal zone, where heat and cold hit hardest during low tide.

“By characterizing oyster distributions in hot southern parts of the range, we were able to predict what will happen under future climate change in more northern, cooler parts of the range,” says Kerstin Wasson, research coordinator at Elkhorn Slough Reserve and lead author of the study. “Understanding how climate shapes where oysters can live helps us plan our restoration efforts.”

Funding from the NERRS Science Collaborative initially launched the NOOC community of practice, she notes, and is still paying dividends today.

Wasson and her collaborators expected to find that extreme heat would limit oysters to the lowest part of the intertidal zone. But to their surprise, they found Olympia oysters doing just fine—and living high up in intertidal areas—in the warmer, southern parts of their range.

“We assumed exposure to heat at low tide set their upper limit,” said Wasson. “But what we found was the opposite—cold temperatures limit how high Olympia oysters can go in the northern part of their range. This means that as our summers become hotter, Olympia oysters will do just fine, and as northern winters become milder, Olympia oysters will actually expand their intertidal distribution.”

The study is a reminder that assumptions about climate change effects are sometimes wrong. Some species will actually benefit, even though many will likely be harmed. It’s also a demonstration of the value of consistent sampling across different geographic areas and allowing for lessons to be shared across a community of practice like NOOC and the Reserve System. 

“This is one of the strengths of the Reserve System,” said Rebecca Roth, executive director of the National Estuarine Research Reserve Association. “Reserves represent the full diversity of U.S. estuaries, and when you combine that with a dedication to collaborating with a wide range of partners, you lay the foundation for smart, lasting investments in coastal restoration.”

The findings also highlight that not only are Olympia oysters adaptable in warming conditions, they also appear resilient to other aspects of climate change. They may benefit in areas where sea level rise floods areas that can be occupied by oysters, and they show resilience to ocean acidification—another growing threat for some shellfish.

Once nearly wiped out by overharvesting and habitat loss, Olympia oysters are making a comeback, and as this study shows, they may have a surprising edge when it comes to adapting to the climate challenges ahead.