Researchers Find Reslient Algae May Help Abalone During Ocean Acidification

New research from Cal Poly and California Sea Grant sounds a hopeful note for the resilience of California abalone in the face of ocean acidification. The study, conducted by Cal Poly biologist Jennifer O’Leary, focuses on crustose coralline algae and their effects on abalone’s ability to reproduce. 

“This research is novel in that it shows that some critical interactions between species can be maintained, even for sensitive species,” O’Leary said. “This is good news for California abalone, as loss of the algae would mean catastrophic declines in abalone replenishment.” 

Pink crustose coralline algae grow on rocks near shore and, like coral, produce a skeleton made of calcium carbonate. California abalone larvae are more likely to settle an area where coralline algae are present because coralline has a scent that abalone use to find the right habitat. Previous studies have shown that coralline algae are sensitive to ocean acidification.  

O’Leary and her fellow researchers wanted to know whether coralline would still provide the right scent for abalone after ocean acidification, which is a result of climate change. 

When carbon dioxide is absorbed by seawater, chemical reactions occur that increase the acidity of the water. Scientists refer to these chemical reactions as ocean acidification. Since the beginning of the Industrial Revolution, ocean waters have experienced a 30 percent increase in acidity, according to the National Oceanic and Atmospheric Administration. 

“Ocean acidification is one of the biggest issues facing marine communities,” O’Leary said. “It’s critical to understand the impacts of this threat and evaluate where and when organisms and communities are able to withstand acidification.” 

After a group of algae were exposed to ocean acidification for four months, researchers tested whether the algae still attracted abalone settlement. The results were encouraging. 

Though ocean acidification reduced algal growth, more than half of the abalone produced larvae when the algae were present, compared with fewer than one in 10 when the algae were not. The researchers concluded that some species interactions may continue despite acidification, which will increase the species’ resilience. 

One possible explanation for these results is that some organisms in California may be better able to withstand ocean acidification because they live in highly variable physical conditions naturally. This explanation needs to be tested before it can be confirmed, O’Leary said.