Warm sea can pull sharks to Antarctica: Potentially serious consequences

It's been 40 million years since the sea water in Antarctica was warm enough to sustain sharks and most fish, but that could be repeated in this century as a result of global warming. . According to scientists at Rhode Island University, if that happens, the impact on the Antarctic ecosystem will be very serious.

Cheryl Wilga and Brad Seibel, URI biology professors, have studied the adaptation and metabolism of sharks and warm marine predators that conclude that the increase is only a few degrees Celsius. can lead some species to the Antarctic waters.

Wilga said: 'Only a few species eat mollusks in Antarctica. Therefore, the Antarctic seabed is dominated by soft-bodied and slow-moving invertebrates. This also happened with the ancient ocean before the crustaceans grew '.

Barely shark sharks in experimental tanks.(Photo: Anabela Maia)

She stressed that many moving sharks have a high level of metabolism because they have to swim continuously to push oxygen into the gills, and they use a large amount of energy just to move. The icy sea water in Antarctica may slow down the metabolic process so that they can survive.

Bottom sharks - sharks that live in the seabed and move very little - have lower metabolic rates and can live in seawater from 7 to 10 degrees Celsius, but most of them are found in places where shallow water has a climate from temperate to tropical. Since they cannot swim large distances and do not produce larvae that are widely dispersed, it is unlikely that these sharks can reach the South Pole themselves.

According to Seibel, sharks accumulate trimethylamine oxide (TMAO) as a normal function of the body, and this demand is even greater in low temperature and high pressure conditions, such as in deep trenches in Antarctica.'It is possible that the amount of TMAO needed to reach a large limit prevents sharks from reaching Antarctica,' he said. 'Interestingly, sharks cannot be found at depths of more than 3,000 meters in Antarctica and globally. '. The seawater surrounding the Antarctic peninsula remains the same for several degrees above freezing temperature, but in the past 50 years the temperature has increased from 1 to 2 degrees Celsius, about two to three times the level of increase. average of the globe.

' Seawater only needs to stay above freezing to allow some shark species to survive, and at the current rate, this could happen in this century. Once there, they will completely change the ecology of the Antarctic seabed community . '

Rough shark shark (Photo: Elasmodiver.com)

Although it does not agree that the presence of sharks and other crustacean fish species will lead to extinction of a number of species on a large scale, Wilga and Seibel think it can create profound changes. about the quantity and proportion of species. Shrimp, some marine species and starfish are most likely to be affected.

' Ice fish - the only vertebrate fish in Antarctica due to its anti-freezing system - will also face a new threat,' Wilga added: 'They are already making food for seals and penguins. . Adding sharks and other vertebrate fish will greatly affect them. '

Crab , another carnivore that has not existed in Antarctic waters for millions of years, is also likely to return. Antarctic sea water in Antarctica reduces the ability to push magnesium out of their blood, leading to coma and death. But the warming of the sea has led some crabs to move closer to Antarctica. The study of 'Physiological restraints on Antarctic carnivores' was presented on February 15 in Boston during the annual meeting of the American Association for the Advancement of Science.

Some pictures of sharks.