High CO2 Prevents Sharks from Smelling (and eating…)

Written by on November 18, 2015 in Marine Life, Sharks

A recent study from the University of Adelaide found that sharks’ growth and hunting abilities will be “dramatically impacted” by climate change.

Port Jackson shark. Photo credit: Mark Norman, Museum Victoria, CC BY 3.0 via Commons.

Port Jackson shark. Photo credit: Mark Norman, Museum Victoria, CC BY 3.0 via Commons.

The results of a long-term experiment show that warming waters and increasing carbon dioxide levels will make it harder for Port Jackson sharks (Heterodontus portusjacksoni) to meet their high energy demands.

In controlled lab settings, researchers found that while embryonic development was faster under warmer conditions, the combination of high temperatures and high CO2 increased the sharks’ energy requirement, reduced their metabolic efficiency, and diminished their ability to smell food. This nasty combination led to drastic reductions in growth rates.

Study leader, Australian Research Council (ARC) Future Fellow, and Associate Professor Ivan Nagelkerken, explained the problem in a news release: “In warmer water, sharks are hungrier but with increased CO2 they won’t be able to find their food.”

This is particularly true for other bottom-dwelling sharks, like Port Jacksons, that rely on their sense of smell to locate prey in the sandy seafloor. PhD student Jennifer Pistevos explained that sometimes the sharks didn’t even bother to look for food under high CO2 conditions.

“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,” Associate Professor Nagelkerken said.

This study highlights the pressing need for shark conservation efforts, since these top predators are already threatened by overfishing.

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Copyright © 2015 by Marine Science Today, a publication of Marine Science Today LLC.

About the Author

About the Author: Emily Tripp is the Publisher and Editor of MarineScienceToday.com. She holds marine science and biology degrees from the University of Miami's Rosenstiel School of Marine and Atmospheric Science and a Master of Advanced Studies degree in Marine Biodiversity and Conservation from Scripps Institution of Oceanography. When she's not writing about marine science, she's probably running around outside or playing with her dog. .

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