Researchers believe climate change could cause sharks to become "right-handed" and deadlier.

(Mark Norman/Museum Victoria)

At a Glance

A new study suggests that climate change could cause sharks to become "right-handed" and deadlier.As ocean waters warm, sharks' embryonic development could be stunted, affecting brain size.Lateralization in smaller brains could cause sharks to become faster-learning predators.

A new study suggests that climate change could cause sharks to become "right-handed" and deadlier, which could send marine ecosystems into imbalance.

A group of Port Jackson sharks, when incubated in water warmed to projected ocean temperatures at the turn of the century if greenhouse gas emissions continue at their current pace,that impacts marine ecosystems, according to research published in the journal Symmetry.

The "handedness" of sharks is decided by their lateralization — the tendency for functions or processes to be taken care of by one side of the brain or the other.

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By splitting up behaviors to one side of the brain versus the other, humans along with other species of animals are believed to be able to make more brain space available for other responsibilities by automating tasks that can raise survival efficiency.

While sharks are more likely to be affected in a negative fashionby climate change — oceans becoming more acidic and — lateralization could enable surviving sharks to become faster-learning predators.

"Lateralization may enable sharks to process information more efficiently, even if their brains are smaller or less well-developed," saidCatarina Vila Pouca, Macquarie University behavioral ecologist and lead author of the study.

Researchers incubated Port Jackson shark eggsin water 3 degrees Celsius warmer– the high end of ocean temperature projections come 2100 – than that of their natural habitat off the coast of eastern Australia.

Only some 60 percent of the sharks survived the embryo stage in the warmer conditions, but the majority of those whosurvived and hatched chose to turn right on a Y-maze. In a control group incubated in a temperature found currently in their natural habitat, the sharks showed no preference.

Because it takes shark embryos up to 10 months to fully develop, changes in the environment — like higher temperatures — can affect growth. With hotter conditions like that expected at the end of the century, the sharks' metabolism could accelerateand cause them to hatch early.

"Brain tissue is metabolically expensive, so if embryos don’t have enough time to develop properly, this is the first thing that will be affected," said Vila Pouca.

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Researchers hypothesized that because the sharks' brains might be unable to grow to the same size and complexity, their lateralization could have stepped in to help extract the same amount of power out of the smaller brains.

While an increase in lateralization may help the sharks better adjust for rising ocean temperatures, it could also lead them to change the way they catch prey and subsequently overpower marine ecosystems, creating an imbalance along the food chain.

“Looking at lateralization can help us understand brain development and its impact on behavior,” said Vila Pouca. “To build a complete picture, we need to investigate how climate change may affect other behavioral traits such as escape responses and learning abilities.”