Shark's Hunting Ability Impaired With Climate Change

Increasing levels of carbon dioxide and warmer waters due to climate change may impede a shark's ability to successfully hunt, according to researchers from the University of Adelaide. In a recent study, researchers looked at the long-term implications of climate change and found that sharks may soon be unable to meet their energy demands and this could have a cascading effect throughout entire ecosystems, according to a news release.

Specifically, researchers studied Port Jackson sharks in a series of laboratory experiments. The sharks were placed in large tanks that simulated their natural habitat and they were provided with natural prey. Then researchers adjusted the living conditions. Elevated temperatures resulted in faster embryonic development but pairing warmer water with higher levels of carbon dioxide resulted in reduced metabolic efficiency that alters a sharks sense of smell. Ultimately, this impacted their ability to hunt and resulted in smaller sharks.

"In warmer water, sharks are hungrier but with increased CO2 they won't be able to find their food," Ivan Nagelkerken, lead researcher and an associate professor from the University of Adelaide, said in the release. "With a reduced ability to hunt, sharks will no longer be able to exert the same top-down control over the marine food webs, which is essential for maintaining healthy ocean ecosystems."

Port Jackson sharks are blunt-headed fish that primarily feed on bottom-dwelling organisms. Generally, the animals can be seen throughout Australian oceans, where they rely on their sense of smell to hunt. All of that represents a double whammy for the sharks, notes Professor Sean Connell, a University of Adelaide marine ecologist, adding, "One-third of shark and ray species are already threatened worldwide because of overfishing. Climate change and ocean acidification are going to add another layer of stress and accelerate extinction rates."

The study was recently published in the journal Scientific Reports.

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