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Climate change makes sharks ‘right-handed’

Climate change makes sharks ‘right-handed’: rising sea temperatures influence the direction in which they choose to swim, study finds

  • Australian scientists have incubated eggs at a temperature predicted for 2100
  • They found that half died within a month, and those who survived became “right-handed” and preferred swimming to the right

Warming oceans are changing the way sharks swim – and they make them right-handed, researchers have discovered.

Australian scientists incubated eggs in heated tanks to simulate temperature changes at the end of the century.

They discovered that half died within a month, and those who survived became “right-handed” and chose to swim to the right, a process known as lateralisation.

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Australian scientists discovered that sharks incubated in tanks simulating temperatures in 2100 became “right-handed” and chose to swim to the right, a process known as lateralization

The researchers discovered that rising temperatures developed the property much faster than they had expected.

“We have incubated and bred Port Jackson sharks at current and projected temperatures at the end of the century and measured preferential detour reactions left or right,” the researchers wrote in a study published in the journal Symmetry.

To test whether the sharks had developed lateralization, the team placed them in a long tank with a Y-shaped partition at one end.

Behind the partition was a food reward; sharks simply had to decide whether to swim to the right or left of the Y to reach their snack.

‘Sharks incubated at elevated temperature showed stronger absolute laterality and were considerably biased towards the right compared to sharks raised at the current temperature.

The researchers say that the changes show that climate change can have a much greater and faster effect on marine brains than expected.

“Climate change is heating the oceans at an unprecedented rate,” they wrote.

‘Under predicted temperatures at the end of the century, many disappointers show disturbed development and changed critical behavior, including lateralization of behavior.

“Because laterality is an expression of brain-functional asymmetries, changes in the strength and direction of lateralisation suggest that rapid climate warming can affect brain development and function.”

Researchers collected a clutch of Port Jackson shark eggs from the waters of Eastern Australia.

They incubated 12 eggs in a tank warmed up to the current ambient temperature of the bay (about 70 degrees Fahrenheit, or 20.6 degrees Celsius) and 12 others in a tank that was gradually warmed up to 74.5 degrees F (23.6 degrees C ) to simulate the predicted values. end of the century sea temperatures.

Five sharks incubated in the elevated temperatures died within a month of hatching.

DO SHARKS HAVE BEST FRIENDS?

For the first time, researchers have shown that sharks over the years display very strong preferences for certain individuals in their social networks, and prefer to hang out with others of the same gender and size.

The study, which included tagging Port Jackson sharks (Heterodontus portus jacksoni), was conducted at Jervis Bay in New South Wales, Australia.

The bay was chosen because there are large seasonal pairings of Port Jackson sharks, a bottom-living species that is endemic to Australia, where both males and females migrate annually from their foraging area in South Australia to return to the same reef in Jervis Bay to breed.

Locations of acoustic receivers deployed in Jervis Bay (NSW, Australia); each circle represents a receiver

Locations of acoustic receivers deployed in Jervis Bay (NSW, Australia); each circle represents a receiver

Locations of acoustic receivers deployed in Jervis Bay (NSW, Australia); each circle represents a receiver

Proximity lumberjacks were attached in 2012 to seven separate sharks and acoustic receivers, attached to the seabed or to lake lines in the middle of the water, allowing sea life in three dimensions to be monitored remotely, were deployed in 2012 and 2013.

The researchers discovered that when the sharks return to their breeding reefs, they do so with incredible accuracy.

The Fish Lab at Macquarie University studies these social interactions between sharks using acoustic tags that identify individual animals when they are within the reach of a recipient.

By analyzing the time stamps of these receivers, the researchers can see with whom and for how long.

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