Friday , January 27 2023

Antarctic winners and losers: how climate change will change the frozen continent – Science News


Antarctic melting has doubled almost in the last five years, according to recent data.

As the ice sheets recede and the seas remain free of ice for more than a year, some animals will benefit from it, while others will suffer from the disappearance of their food and habitat.

Now the scientists have tried to quantify which animals will be the winners and losers as the frozen continent thaws.

In research published today in the Marine Science Borders, scientists calculate the influences of pH, salinity, food availability, ice retention, sea ice loss, human impact and UV growth and wind on Antarctic animals in the near future.

Researchers calculated the net benefit / impact of changes for each species using a simple, non-weighted scoring system.

For example, if the temperature was calculated to benefit an animal, this species received 1 point. If a decrease in food availability is foreseen, this species has lost one point.

Although global diversity will be reduced, some animals may benefit from a new habitat, according to lead author Simon Morley of the British Antarctic Survey (BAS).

"Of course, the big question beyond this is how long this positive feedback will last. That's the real golden question."

Winner: Southern right whales

Southern law baths were pushed to the brink of extinction by whales in the early 1900s when only 300 individuals remained. They have easily recovered to about 3,500 whales, but are still considered to be endangered.

According to this research, they expect to benefit in the short term as sea ice recipe, with a net profit of 4 in general, according to Dr. Morley.

"So with less sea ice, more light in the water, more productivity, you would expect more copepods and therefore the southern right whale would benefit."

Lost: Krill

Sea ice offers an essential habitat for krill in the Antarctic, which in turn is the main source of food for some whales, penguins and marine animals.

Krill is also fed with algae that grow on the bottom of the sea ice, and krill numbers are already declining as sea ice retreats to Western Antarctica, according to researchers.

Last year's research predicted that the number of krill would drop by some 40% in some Antarctic waters due to ice loss at sea and commercial harvesting.

The study today gave a krill an impact score of -2, with sea ice and ocean acidification adversely affecting populations.

Lost: humpback whales

The decline of krill is expected to hit populations of heavy cocks whale.

Humpbacks spend corms in Antarctic waters, building fat stores that can survive their long migration to the north to be grown in southern hemispherical winter.

It was believed they could go up to eight months without eating after the krill fattening.

According to today's research, ocean acidity and food loss will exert pressure on future populations.

Lost: emperor penguins

Enemy penguins have a broad diet that includes krill, fish and squid, but researchers do not predict that the decline in krill will significantly affect their number.

Decreasing sea ice could actually open the penguin feeding area.

However, this benefit is likely to be abolished, as split penguins use ice and ice shelves as reproductive habitats, according to Dr. Morley.

"This is the biggest signal of climate change in the Antarctic Peninsula – losing sea ice, glaciers and ice shelves."

Lost: Adelie and the penguins of the chinstrap

Penguins Adelie and chinstrap were both marked -4.

According to researchers, Adelie and Chinstrap penguins already show signs of disturbance due to ice loss at sea.

Recent studies from several sites in the Western Antarctic Peninsula and Scotland Sea Region have provided strong evidence of changes in the distribution of both Adelie penguin populations and quinstrap, they say in the newspaper.

The loss of krill, acidification of the oceans, snow growth and the sharp decline in sea ice are expected to have negative effects on their populations in the near future.

Winner: King Penguins

Like the southern whales, Dr. Morley predicts that rising ocean productivity could be beneficial to the numbers of King Penguins in the short run.

King of the penguins feed on mycophyses, also known as lanterns, because they are positioned vertically in the water column.

Small fish is also an alternative feed for krill for other animals, such as squid.

King of the penguin has achieved a positive impact of 3 in this study and is expected to benefit from ice reduction at sea, collapse on ice shelves and warmer waters.

Winner: Starfish

Flag and other bottom feeding generics are expected to get more benefits from lowering ice, according to Dr. Morley.

"A new habitat will open for animals living on the seabed and for those who feed on open water, so they are mostly animals that have gone out with their positions," he said.

Fish fish feed on the ocean floor, often shaking the debris that fell from above.

In Antarctica, changing icebergs kills many animals and provides care for the caretaker.

"In the environment, there will be more icebergs in its habitat, so there will be more dead animals killed by icebergs, so predators will benefit from it," said Dr. Morley.

Winner: jellyfish

As ocean temperatures increase, jellyfish numbers grow throughout the world.

According to Dr. Morley, this will probably apply to Antarctic waters.

"Jellyfish are one of these open water feeders," he said.

Jellyfish are able to withstand low oxygen conditions as well as fluctuations in water acidity, while many of their predators are not.

Lost: Seal of fur

Antarctic fur cigars eat mainly krill and, like humpback whales, are expected to suffer as krill drops.

However, populations of fur seals on Macquarie Island in the Southwest Pacific eat fish and squid so they can change their diet.

Acidification of oceans, sea ice loss and temperature are predicted to indirectly affect fur populations in the near future.

"Nothing to worry" about the wrong conclusion

While this research looks at short-term environmental changes from heating, Dr. Morley acknowledges that as heating continues, any potential benefits can be canceled.

"At some point, those shallow water habitats I described as available for these animals will become potentially too hot, too acidic," he said.

"The whole food network will be interrupted. There could be links in the food network that we do not yet understand, which could be affected by these changes, which may neglect some of what we are seeing here."

Zanna Chase of the Institute of Marine and Antarctic Studies at the University of Tasmania (IMAS) said that particular attention is needed in interpreting results based on a simple, non-weighted method.

"I would not say it is final, but at least it has highlighted the problems and the players and gives some indication of what we could expect."

Dr. Morley recognizes the limits of the approach.

"Indeed, this is a great simplification, but at this stage is all we can do," he said.

"It is a fairly complex story and this is one of the messages we are trying to overcome, it is complex. Our goal in this paper is to prioritize future research."

Doctor Chase agreed that research is a good start, but warned people to misinterpret the benefits for certain species.

"People could read this and believe there is nothing to worry about," she said.

So there is a risk of making a risk assessment with this conclusion.

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