قالب وردپرس درنا توس
Home / World / This year, sharks have killed seven people in Australia, the most since 1934. Climate change can be a factor

This year, sharks have killed seven people in Australia, the most since 1934. Climate change can be a factor



The search days revealed a surfboard, but his body was never found. This year, he was named the seventh victim of a shark attack in Australia – an alarming jump that has not been observed in the country for 86 years.

“It’s a bit of a failure in Australia (this year),” said Coole Brown, a professor of biological sciences at Macquarie University in Sydney. “And in fact the long-term average is one to one fatal situation a year. So seven is a lot more, no doubt.”

On average, one death per year has remained stable for the past 50 years, a Taronga spokesman said.

This is not because shark attacks have risen sharply in Australia as a whole ̵

1; there have been 21 shark incidents this year, which is normal and in line with previous years. The difference is in the mortality rate.

The climate crisis in Australia has been mounting for years, but no one has listened

There are a number of possible explanations – several experts have noted that the figures always fluctuate from year to year, and this may be just a misfortune. But there is another possible culprit: the climate crisis.

As the oceans heat up, entire ecosystems are destroyed and forced to adapt. Fish migrate to places they have never been before. The behavior of species is changing. And as the marine world transforms, sharks follow their prey and approach popular shores.

Australia is a hot spot for global warming

On land, the climate crisis in Australia has led to violent fires in the bushes, extreme heat and one of the worst droughts ever recorded.

But it has also caused the oceans to acidify and rise in temperature, which could wreak havoc on entire ecosystems. In particular, the south-eastern region of Australia is at the forefront of the climate crisis – near-surface water warming there is about four times the global value.

The Great Barrier Reef, a vital marine ecosystem along the east coast, has undergone such large-scale multiple bleaching that more than half of the coral on the reef is dead. Over the past decade, massive areas of mangrove forests have also perished.

“These two ecosystems are themselves responsible for the huge diversity of marine ecosystems – so you see huge ecosystems disappearing and / or moving,” Brown said.

This all means that the animals migrate further south than usual in search of a suitable environment. Species such as the yellow-tailed kingfisher, which can usually be seen in northern tropical waters, appear in flocks near the southern island state of Tasmania. The common Sydney octopus has moved from the northeastern state of Queensland to Tasmania. Even plankton and plant plants, such as algae, are moving south.

These types of “sea tropical tramps” often travel along the coast, Brown said, riding on the East Australian Current, famously portrayed in the film “Finding Nemo.” But now climate change means that the winter is warm enough for these fish to survive the season – so some species have decided to stay permanently in southern waters.

“I spend a lot of time on boats off the coast, and this year I don’t remember a year when I saw so many bait units so close to the coast,” Brown said. Researchers are still not sure exactly what drives the movement of many of these species – but Brown added: “There is no doubt that sharks simply react to where the luring fish is.”

Sharks monitor water temperature

The ocean is by no means a stagnant mass; Intense currents mean that there are areas with hot and cold water. The East Australian Current is a major player in this dynamic – it has also intensified much in recent decades, meaning it is pumping more warm tropical water down the coast.

But because the current is more intense, it also pushes cold nutrient-rich water to some eastern shores.

These dynamic, changing water temperatures may also be the reason that sharks begin to move into human spaces. Some species, such as bull sharks, love warm water, so they spend more time in warm southern waters, said Robert Harcourt, a shark ecology researcher and director of the Macquarie Marine Predator Research Group.

Meanwhile, species such as large whites, which prefer lower temperatures, are approaching the shores, where pockets of cold water also contain large prey. Tiger sharks are usually found north, but they went to Sydney, which is probably also affected by the current.

Bull shark photographed in Queensland, Australia.

These three species – the bull, the great white and the tiger shark – are responsible for most shark attacks in Australia.

“I predict that many of these species will have more movement, more geographic range,” Harcourt said. “This is because the dynamics of climate change mean that their respective habitats in terms of water temperature and distribution of prey are also changing. And these animals are large, distant predators at the top.”

“They have the potential to have more contact with people, and at the same time the use of people by the ocean is constantly increasing,” he added.

There are other possible factors

Modern technology, improved health care and faster emergency response times mean that the death rate from shark attacks has dropped significantly over the past decade – which is why this year’s jump is a “real anomaly,” Harcourt said.

But there may be other factors in the direction of climate change. Luck is paramount: there have been several close calls in recent years when the victim was rescued because a medical worker was nearby at the time, Brown said.

“Over the last couple of years, we have managed to save several people, only due to the fact that someone is qualified on the spot to deal with the injury immediately, and this significantly changes the situation,” he added.

The number of shark attacks is increasing, but the risk is low, research shows

It also depends on where the victim was bitten. “One centimeter to the left if you are bitten on the leg and you can die in at least seconds or minutes,” Garcourt said. “You know, one inch to the right you get a terrible scar and severe pain, but if you don’t go into shock, you have a great chance of surviving.”

There is also a chance that this year people will simply spend more time in the water due to working conditions at home during the Covid-19 pandemic or because it has been particularly hot in Australia recently, Harcourt said – thus increasing the chances they could encounter shark.

We are in a new era of unpredictability

Brown and Harcourt warned that the death rate from shark attacks in 2020 is based on only one-year data; Given that sharks can fluctuate from year to year, it is difficult to say whether climate change is directly causing the jump this year. It may just be a matter of misfortune; we simply cannot know for several years when there will be enough data to determine whether this is a trend or a deviation.

But both experts agreed on one thing: the ocean is changing, and sharks are changing with it. Climate change has destroyed the natural environment in the world and upset everything, disrupting the way of life, movement and potential interaction of marine ecosystems with humans.

“You can’t draw any conclusions about anything based on (just one year), but there’s no doubt that we’re actually moving into a period of uncertainty,” Brown said.

“All the old distributions of species and how we interact with them, you can throw it out the window. Whatever happens in the future will be new.”


Source link