Quantcast
Environmental News for a Healthier Planet and Life

Marine Heat Waves Could Threaten Dolphin Survival, Study Suggests

Popular
Marine Heat Waves Could Threaten Dolphin Survival, Study Suggests
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.

Reindeers at their winter location in northern Sweden on Feb. 4, 2020, near Ornskoldsvik. JONATHAN NACKSTRAND / AFP via Getty Images

Sweden's reindeer have a problem. In winter, they feed on lichens buried beneath the snow. But the climate crisis is making this difficult. Warmer temperatures mean moisture sometimes falls as rain instead of snow. When the air refreezes, a layer of ice forms between the reindeer and their meal, forcing them to wander further in search of ideal conditions. And sometimes, this means crossing busy roads.

Read More Show Less

EcoWatch Daily Newsletter

The Great Lakes, including Lake Michigan, experienced some of their warmest temperatures on record in the summer of 2020. Ken Ilio / Moment / Getty Images

Heatwaves are not just distinct to the land. A recent study found lakes are susceptible to temperature rise too, causing "lake heatwaves," The Independent reported.

Read More Show Less

Trending

Starfish might appear simple creatures, but the way these animals' distinctive biology evolved was, until recently, unknown. FangXiaNuo / Getty Images

By Aaron W Hunter

A chance discovery of a beautifully preserved fossil in the desert landscape of Morocco has solved one of the great mysteries of biology and paleontology: how starfish evolved their arms.

Read More Show Less
U.S. President Joe Biden sits in the Oval Office as he signs a series of orders at the White House in Washington, D.C. on January 20, 2021. Jim Watson / AFP / Getty Images

President Joe Biden officially took office Wednesday, and immediately set to work reversing some of former President Donald Trump's environmental policies.

Read More Show Less
Erik McGregor / LightRocket / Getty Images

In many schools, the study of climate change is limited to the science. But at the University of Minnesota, Twin Cities, students in one class also learn how to take climate action.

Read More Show Less