Climate Change Is Likely Impacting Marine Life More Than Previously Thought, Study Finds

Redfin needlefish hiding under the sea surface near Curaçao. Study co-author Juliette Jacquemont / University of Washington Seattle

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The impacts of climate change on marine life, from rising sea surface temperatures to ocean acidification, have long been studied, but new research is shedding light on the extent of these effects both currently and in the future.

Scientists developed a method that fully considers the consequences of warming oceans and acidification on fish and invertebrate animals, without canceling out certain other impacts, such as when one species begins eating more and another eats less.

“To gain a better understanding of the overall worldwide impact of climate change, marine biologists calculate its effects on all fish or all invertebrate species lumped together,” Katharina Alter, of the Royal Netherlands Institute for Sea Research (NIOZ) and lead author of the study, explained in a statement. “Yet, effects determined in different individual studies can cancel each other out: for example if invertebrate animals such as snails profit from a certain environmental change and other invertebrates, such as sea urchins, suffer from it, the overall effect for invertebrates is concluded to be zero, although both animal groups are affected.”

Previously, scientists determined three main ways that climate change can affect marine life, including reduced chances of survival, increased metabolism and weakened skeletons of invertebrates. By using the new method to evaluate the effects of climate change on marine life, researchers found negative impacts on behavior, physiology, reproduction and physical development for fish and invertebrates.

According to Alter, these findings, which were published in the journal Nature Communications, showed that the negative consequences on marine life are likely greater than previously thought.

The researchers also estimated how acidification, which happens as increasing amounts of carbon dioxide in the air dissolve into the ocean, could continue to impact marine life in the future, both with and without intervention.

“Our new approach suggests that if ocean warming and acidification continue on the current trajectory, up to 100% of the biological processes in fish and invertebrate species will be affected, while previous research methods found changes in only about 20 and 25% of all processes, respectively,” Alter said.

Even in a lower carbon emissions scenario, the researchers determined that acidification will impact about 50% of biological processes in invertebrates and 30% of biological processes in fish, still higher than previous estimates.

In addition to calculating negative impacts of climate change on fish and invertebrates, the researchers considered any potential beneficial outcomes for species for a more comprehensive look at all “hidden impacts” that ocean warming and acidification have on marine life.

“The new calculation method weighs the significant deviation from the current state irrespective of its direction — be it beneficial or detrimental — and counts it as impact of warming and acidifying seawater,” Alter said. “With our new approach, you can include the broadest range of measured responses and detect impacts that were hidden in the traditional approach.”

The study authors noted that more research is needed to determine links between the changes to biological processes, both positive and negative, in marine life and how these could affect ecosystems at large.

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