Quantcast

Marine Heat Waves Could Threaten Dolphin Survival, Study Suggests

Popular
The survival rates of Indo Pacific bottlenose dolphins like this one were reduced following a marine heat wave in Australia. Graeme Snow

Climate change could have a deadly impact on dolphins and other marine mammals.


That's the saddening implication of a study published in Current Biology Monday. Researchers looked at what happened when a marine heat wave scorched waters off the coast of Western Australia in 2011. What they found was that the survival rate of dolphins in the area declined by 12 percent and that female dolphins gave birth to a smaller number of calves. The effects lasted up until 2017.

"The extent of the negative influence of the heat wave surprised us," lead study author and University of Leeds PhD student Sonja Wild in a statement reported by USA Today. "It is particularly unusual that the reproductive success of females appears to have not returned to normal levels, even after six years."

The researchers had been studying dolphins in an area known as Shark Bay, a World Heritage Site home to Indo-Pacific bottlenose dolphins. The 2011 heat wave, which raised ocean temperatures in the area as much as four degrees Celsius above average, killed off seagrass and fish in the iconic bay, a University of Bristol press release explained.

The researchers wanted to know if the seagrass die-off had impacted larger animals.

"It was serendipity really. We have been working in that part of Shark Bay since 2007, now as part of a large study," study author and Department of Anthropology at the University of Zurich Director Michael Krützen told CNN in an email.

The researchers reviewed more than 5,000 dolphin encounters between 2007 and 2017 and found that the heat wave had indeed had a lasting impact, according to the press release. Researchers thought that the loss of food and habitat meant that fish in the area could not recover quickly. This forced dolphins to spend more time hunting, making them less aware. This in turn increased the chances that sharks would prey on calves. In addition, the researchers thought that the lack of nutrition might have made it harder for both mothers and young dolphins to get enough to eat, leading to more calf deaths.

For the researchers, the findings were yet another example of the threat climate change poses to the oceans. A study published in March for example, found that the number of ocean heat wave days per year had increased by 50 percent between 1987 and 2016 and that they had the same destructive impact on marine ecosystems as wildfires on land.

"Given that marine heatwaves are occurring more often in association with climate change this raises serious concerns over the long-term prospects for the dolphin population, commercial fisheries and the ecosystem as a whole," senior study author and senior research associate at Bristol's School of Biological Sciences Dr. Simon Allen said in the press release.

The one silver lining from the study was that dolphins that used sponges to hunt were not as impacted as those who did not, but the researchers did not know if that advantage would hold for an extended period of time, CNN reported.

"It seems that extreme weather events appear to threaten marine mammal populations in their existence. If we want to conserve these populations, we have to think how the frequency of such events can be kept at a minimum," Krützen told CNN.

EcoWatch Daily Newsletter

By Joe Vukovich

Under the guise of responding to consumer complaints that today's energy- and water-efficient dishwashers take too long, the Department of Energy has proposed creating a new class of dishwashers that wouldn't be subject to any water or energy efficiency standards at all. The move would not only undermine three decades of progress for consumers and the environment, it is based on serious distortions of fact regarding today's dishwashers.

Read More Show Less

By Emily Moran

If you have oak trees in your neighborhood, perhaps you've noticed that some years the ground is carpeted with their acorns, and some years there are hardly any. Biologists call this pattern, in which all the oak trees for miles around make either lots of acorns or almost none, "masting."

Read More Show Less
Sponsored

By Catherine Davidson

Tashi Yudon peeks out from behind a net curtain at the rooftops below and lets out a sigh, her breath frosting on the windowpane in front of her.

Some 700 kilometers away in the capital city Delhi, temperatures have yet to dip below 25 degrees Celsius, but in Spiti there is already an atmosphere of impatient expectation as winter settles over the valley.

Read More Show Less

The Dog Aging Project at the University of Washington is looking to recruit 10,000 dogs to study for the next 10 years to see if they can improve the life expectancy of man's best friend and their quality of life, as CNN reported.

Read More Show Less
Warragamba Dam on Oct. 23 in Sydney, Australia. Sydney's dams have been less than 50 percent full as drought conditions continue across New South Wales. Brook Mitchell / Getty Images

While Sydney faced "catastrophic fire danger" for the first time earlier this week, and nearly 130 wildfires continue to burn in New South Wales and Queensland, Sydney now faces another problem; it's running out of water.

Read More Show Less
Sponsored
The European Investment Bank will stop lending for fossil fuel projects. ForgeMind Archimedia / CC BY 2.0

By Eoin Higgins

Climate activists celebrated Thursday the decision of the European Investment Bank to stop funding most oil and coal projects by 2021, part of a bid to be the world's first "climate bank."

Read More Show Less
Campaigners from Friends of the Earth Scotland gather to demand clean air in August 2015. MAVERICK PHOTO AGENCY / Flickr / CC BY 2.0

Air pollution particles from motor vehicle exhaust have been linked to brain cancer for the first time, researchers at McGill University in Montreal say.

Read More Show Less
A measure that would fine parents who refuse to vaccinate their children passed Germany's parliament Thursday. Self Magazine / CC BY 2.0

A measure that would fine parents who refuse to vaccinate their children for measles close to $2,800 passed Germany's parliament Thursday, the Associated Press reported.

Read More Show Less