Scientists at the University of Virginia have investigated how the behavior of Antarctic fish has changed as a result of the warming of the Southern Ocean.

The authors of the new work studied the changes in the behavior of marine animals in the Southern Ocean to understand how they would respond to heat stress caused by the increase in temperature.

At first glance, Antarctica looks unfriendly, but completely different biological species live in the waters of the Southern Ocean – sea ice algae and cyanobacteria, krill, crustaceans and others.

In particular, fish play a vital role in the Southern Ocean food web – there are approximately 9,000 species of them – but they could be threatened by climate change and, consequently, rising ocean temperatures. Climate analysis in 2021 showed that some areas of the Antarctic continental shelf will be at least 1 ° C warmer by 2050.

The authors of the new work described how two species of Antarctic fish react to an increase in water temperature – with and without hemoglobin in their blood. The research team noted that both species reacted to warming with a complex set of behavioral patterns – the fish began to actively flap and spread their fins, often swim to the surface to breathe, and also briefly changed activity to rest.

The authors note that heat stress in fish increases the temperature of the central nervous system and target tissues, such as skeletal and cardiac muscles, and decreases the availability of oxygen. According to the results of the experiment, it turned out that fish with and without hemoglobin can adapt to heat stress, but they do it in different ways, the former begin to actively move in order to increase the ventilation of the gills, and the latter actively fan themselves with their fins.

According to the researchers, the fish’s behavior was frightening, but despite this, they showed that they are able to adapt to changes in temperature.