Antarctic marine life adapted to the cold. Now the ocean is getting warmer

Like other Antarctic animals, spiny scavenger fish may not be able to survive in warming waters.

Lloyd Peck/British Antarctic Survey

Despite the Southern Oceanfreezing temperatures, thousands of marine species live in these Antarctic waters. Over millennia, they have adapted to the extreme environment — but under the veil of a worsening climate crisistheir life-saving adaptations can gradually turn into survival disadvantages.

In the journal Royal Society Open Science on Wednesday, researchers warn that in exchange for adapting to icy seas, Antarctic creatures have lost their ability to grow and thrive healthily in warm waters. Due to global warming, however, hot water is precisely what the future holds for them.

“As ocean temperatures rise with global warming, this is a timely reminder of the differences between species that have evolved to live at very different temperatures,” said Keiron Fraser, a marine biologist at the University of Plymouth and lead author, in a statement. “If Antarctic fish are increasingly exposed to higher temperatures, this will have implications for their survival, as well as effects on many critical physiological processes, including growth.”

The researchers arrived at their conclusions by comparing two types of fish, one native to Antarctica and called the spiny scavenger fish and the other acclimated to warmer regions and called the shanny. They looked at how fish react to the same water temperature of 3 degrees Celsius (37.4 degrees Fahrenheit).

The researchers chose this experimental climate because it is both warmer than Southern Ocean temperatures, which reach lows of minus 2 degrees Celsius (28.4 degrees Fahrenheit), and colder than the original reservoir. shanny subjects located in uk. When the researchers collected the shannies, these animals were in a commercial enclosure heated to around 14 degrees Celsius (57.2 degrees Fahrenheit), the newspaper said.

After the fish were exposed, the team discovered that the spiny plunderer fish consumed 20% less food than the shanny and grew at only half its rate.

According to the study, this observed blockage in growth is due to the fact that the spiny scavenger fish’s cold-water-specific protein metabolism did not perform well in warm water. In other words, his body couldn’t break down proteins efficiently to facilitate growth at the high temperatures he’s not used to. On the other hand, the shanny didn’t seem to struggle much, which also suggests that fish from temperate climates have a better chance than fish from Antarctica of adapting to new climates.

“Antarctic fish are highly thermally constrained and cannot live long-term at temperatures much higher than they currently inhabit,” Fraser said. “In contrast, many temperate species are more tolerant of a wide range of temperatures because they often inhabit wide latitudinal ranges.”

Additionally, the researchers point out that beyond their own study, many cold-water species studied so far have been seen to experience similar issues with protein metabolism. “It appears to be a pervasive constraint to life at low temperatures,” said Lloyd Peck, a physiologist at the British Antarctic Survey who studies animal adaptations in extreme environments, in a statement.

And that’s right on the note of protein metabolic constraints.

According to the researchers, the approximately 20,000 species in the Southern Ocean have developed many other cold-water-specific body modifications that may not bode well in warm climates.

“There are many other unique adaptations in Antarctic marine species, such as 16 species of fish which are the only animals whose spine does not have red blood cells or hemoglobin to carry oxygen around. their bodies, or giant spider crabs thousands of times heavier than the largest in temperate zones,” Peck said.

Many of these adaptations make it easier to live in an environment with constantly low temperatures. But, like the problem of protein metabolism, they could be detrimental to the animal in changing and heating environments. So, given the terrifyingly rapid rate of global warming, Peck calls the outlook “bleak” for many Antarctic marine species.

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