Why herbivores can help protect ecosystems from climate change

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Plant eating animals have been shown to help their fellow critters survive sharp changes in temperature, offering some hope for defending sea creatures against climate change.

Herbivores might even be the key ingredient in helping ecosystems survive global warming, research from the University of British Columbia has found.

“The herbivores created space for other plants and animals to move in and we saw much more diversity and variety in these ecosystems,” the study’s lead author Rebecca Kordas said. “We want variety because we found it helps protect the ecosystem when you add a stressor like heat.”

Salt Sea Island, British Columbia
The researchers created a mini ecosystem on Salt Sea Island (jeu/Getty Images)

Numerous species occupy the intertidal zone, the area of the shore between the low and high tide, and the animals have to cope with a huge change in temperature every day – sometimes as much as 20 to 25 degrees Celsius.

The starfish, anemones, mussels, barnacles and seaweed that live in the zone are “already living at their physiological limits, so a two-degree change – a conservative prediction of the warming expected over the next 80 years or so – can make a big difference,” Kordas said.

When heatwaves happen in British Columbia or the Pacific Northwest, mass deaths of numerous intertidal species have been observed.

In looking for solutions for the at-risk creatures, Kordas and her team created mini-marine ecosystems on the shore of Ruckle Park on British Columbia’s Salt Spring Island.

Limpets are like snails, but with a cone-shaped shell (Rebecca Kordas)
Limpets are like snails, but with a cone-shaped shell (Rebecca Kordas)

The hard plastic plates the ecosystems lived on allowed the researchers to control the temperature, with some allowing limpets – which are voracious herbivores – in, and some keeping them out.

Researchers found that when temperatures were at their highest, during the summer months, the communities could continue to thrive even if they were heated – but only when the limpets were present.

Christopher Harley, a professor of zoology at UBC and senior author on the study, said that consumer species like limpets, sea otters and starfish are important to maintaining biodiversity, and can make ecosystems more resilient.

“We should be thinking of ways to reduce our negative effects on the natural environment and these results show that if we do basic conservation and management, it can make a big difference in terms of how ecosystems will weather climate change,” he said.