Climate change is weakening communities of colorful creatures in the rocky intertidal zone on the Oregon Coast.
Many Oregonians learn about these ecosystems on tidepooling trips to the beach. New research from Oregon State University suggests that the intricate and visually stunning communities of sea stars, anemones, mussels and more are struggling to recover after disturbances to their environment.
The researchers say that as major disruptive events like marine heatwaves or disease epidemics become more frequent with climate change, these ecosystems could eventually reach a “tipping point” where species start to disappear entirely from Oregon’s intertidal zone.
“What we’re taking this as is an early warning sign that things might be changing,” said Sarah Gravem, a research associate at OSU.
The researchers studied six sites in three coastal areas in Oregon: Cape Perpetua, Cape Foulweather and Cape Blanco. Each site had five plots where they mimicked disturbances by clearing creatures big enough to see from the plots each spring. They placed the “disturbed” plots adjacent to control plots that they didn’t touch to see the contrast.
Every year, over the course of nearly a decade, they measured how communities bounced back after the simulated disturbances by looking at what organisms and how many returned to the test plots.
They found that, over time, marine species took longer to recolonize the bare rock on the test plots.
“The speed of recovery was slowing down,” said Bruce Menge, a professor of integrative biology at OSU and the study’s lead author. “Each year, the system got further and further away from what the original system had looked like.”
The creatures that occupy the intertidal zone are not necessarily on the path to extinction, but the research indicates that the effects of climate change could get them there quicker. And if one dominant species is extirpated, it could have cascading effects on the rest of the intertidal zone.
For example, if mussels disappeared from the coastal ecosystem, species that depend on mussels for food or shelter would likely soon follow. Then the species that depend on them would disappear, and so on and so forth.
“This system, it’s not a forest, it’s not a grassland. It’s not something that people typically live in,” Menge said. “But it’s a model system for how these other systems might change.”
Gravem noted that species occupying the intertidal zone are very resilient and that many people are working to find solutions to the climate crisis. In that, she finds hope for preserving these kaleidoscopic coastal ecosystems.
“These systems will come back if we give them the breathing room,” Gravem said. “If we listen to the folks that are at the forefront of climate solutions, it will be fine. We just have to do what they say.”
The study was published online Monday in Proceedings of the National Academy of Sciences.