Climate change destabilizing ecosystems along Oregon coast

(CN) — Researchers from Oregon State University found the intertidal ecosystems along the Oregon coast are being destabilized by climate change.

In an article published Monday in the journal Proceedings of the National Academy of Sciences, the researchers outline the results of a multi-year experiment, which show that the tide pools at six sites across the Oregon coast are not recovering from disturbances as well as they once did. They point to climate change as the culprit for the increasingly precarious state of the ecosystems.

Postdoctoral researcher and co-author Sarah Gravem explained in an interview that they monitored how the intertidal ecosystems at all the sites responded to disturbances. Some tide pools were left undisturbed, while once a year, others were intentionally cleared of all the visible life forms, like mussels, sea anemones, snails and crabs. After the pools were cleared, they were monitored over time to see how steadily they recovered.

“What we are seeing is that the recovery is slowing down,” said Bruce Menge, a professor of integrative biology who has studied the coast for four decades.

Gravem said scraping of the rocks at the sites each spring is meant to model climate change-related events, like marine heat waves or extreme wave events that disturb the ecosystems.

“We’re mimicking the types of things that climate change does and tracking how fast [the system] responds, and what we’re finding is the system’s getting less good at recovering,” Gravem said. “That is an early warning signal that things aren’t as healthy as they once were.”

Both said tracking recovery of the intertidal zone across years was necessary to understand the consequential yet often gradual effects of climate change.

“The only way to really figure out how quickly the changes are occurring and whether there are trends is to follow particular patches of real estate on the rocks to see the kinds of changes that occur in unmanipulated places and how well the manipulated ones are able to rebound to their previous state,” Menge said.

The intertidal zone proved to be the optimal place to examine the effects of climate change on ecosystems over time. Waves and tides make the intertidal environment highly dynamic. The lifespans of the organisms in the ecosystem are shorter, so they reproduce and develop quickly. The tide pools and spaces between high tides and low tides are relatively compact. All of this allows researchers to measure and track changes across the whole ecosystem over a relatively short amount of time.

“The entire ecosystem is collapsed into something where you can walk from one end of the range to the other,” Gravem said. She noted that, unlike other ecosystems, scientists can add and remove entire elements from the system and monitor the effects. “It really lends itself well to understanding change and how systems work. And then we can translate that to systems that are a lot harder to study.”

The study is funded by the National Science Foundation for the next five years, and Menge said it could go on indefinitely. Both said they are now looking to see whether the increased instability of the ecosystem will reach a tipping point where the whole system drastically changes.

“We tend to think of climate change as this slow march because we don’t often see things changing right in front of our eyes,” Gravem said. She noted that effects of climate change can start out almost undetectable before building to a tipping point like a forest fire, drought or disease from which the diminished ecosystem cannot recover. Menge pointed to the vanishing of sea stars due to climate change as an example of how ecosystems can struggle to rebound.

Both said reversing the effects of climate change is crucial to avoiding an irreversible breakdown of the current intertidal ecosystem. Gravem said they worry such a breakdown could be coming, which is why continued research is important.

“We want to catch [that tipping point] so that we can show how drastic and urgent the need is to change our behavior as humans,” Gravem said.

“The only way we’re going to really address climate change is through immediate and drastic attention to reducing carbon emissions. That’s really the only thing that’s going to stop this,” Menge said.

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