How Giant Kelp May Respond to Climate Change

from UC Davis Science & Climate

In a changing ocean, giant kelp’s reproductive success depends on where it’s from.

Hollarsmith’s study, published in the Journal of Experimental Marine Biology and Ecology, examines how giant kelp may respond to increased ocean warming and acidification. The authors investigated the reproductive success of giant kelp populations in Northern California, Southern California and Chile by exposing them in a laboratory to a range of temperatures and pH levels.

Like someone from Minnesota being dropped into an Arizona heat wave, giant kelp living in cooler, high-latitude waters were more vulnerable to excessive heat than kelp already living in warmer, Southern California waters. The high-latitude kelp completely failed to reproduce when stressed by the heat.

“Just because giant kelp grows in Baja doesn’t mean populations in Northern California or Alaska will be resistant to these heat wave events,” said Hollarsmith, currently a postdoctoral fellow at Simon Fraser University. “They are the same species, but each population might be distinct, which has consequences for how giant kelp will respond to changes in climate and upwelling patterns.”

“This study gave me some hope,” Hollarsmith said. “The fact that ocean acidification was not negatively affecting them, and that some populations still completed their life cycles in warm, 68-degree temperatures, shows that at least some populations are quite resistant. That knowledge can help move us forward.”

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