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

Large food companies are following in the footsteps of fast-food restaurants such as Burger King and KFC by offering meat alternatives. Getty Images

By Elizabeth Pratt

  • Hormel, Kellogg's, and Kroger are among the large companies now planning to offer "fake meat" products at grocery stores.
  • Experts say the trend toward plant-based meats coincides with consumers' desires to eat less meat.
  • However, experts urge consumers to closely check package labels as a product isn't necessarily healthy just because it's described as plant-based.

In grocery stores and fast-food outlets around the U.S., a revolution is taking place.

Read More Show Less
Colombia rainforest. Marcel Oosterwijk / CC BY-SA 2.0

By Torsten Krause

Many of us think of the Amazon as an untouched wilderness, but people have been thriving in these diverse environments for millennia. Due to this long history, the knowledge that Indigenous and forest communities pass between generations about plants, animals and forest ecology is incredibly rich and detailed and easily dwarfs that of any expert.

Read More Show Less
Sponsored
picture-alliance / Newscom / R. Ben Ari

By Wesley Rahn

Plastic byproducts were found in 97 percent of blood and urine samples from 2,500 children tested between 2014 and 2017, according to a study by the German Environment Ministry and the Robert Koch Institute.

Read More Show Less
Pexels

Medically reviewed by Daniel Bubnis, MS, NASM-CPT, NASE Level II-CSS

Written by James Roland

Hot yoga has become a popular exercise in recent years. It offers many of the same benefits as traditional yoga, such as stress reduction, improved strength, and flexibility.

Read More Show Less
Lara Hata / iStock / Getty Images

By SaVanna Shoemaker, MS, RDN, LD

Rice is a staple in many people's diets. It's filling, inexpensive, and a great mild-tasting addition to flavorful dishes.

Read More Show Less
Sponsored
Hinterhaus Productions / DigitalVision / Getty Images

By Lindsay Campbell

From pastries to plant-based—we've got you covered.

Read More Show Less
An image of the trans-alaskan oil pipeline that carries oil from the northern part of Alaska all the way to valdez. This shot is right near the arctic national wildlife refuge. kyletperry / iStock / Getty Images Plus

The Trump administration has initialized the final steps to open up nearly 1.6 million acres of the protected Alaskan National Wildlife Refuge to allow oil and gas drilling.

Read More Show Less
Westend61 / Getty Images

By Elizabeth Streit, MS, RDN, LD

Vegetarianism has become increasingly popular in recent years.

Read More Show Less