A number of invertebrate species have made some of the coldest waters on Earth their perfect home, adapting to fulfill every neighborhood need. These creatures—including sea spiders, isopods, and an array of corals—recycle nutrients, provide food for larger animals, like penguins and seals, and provide habitat.
Warming waters threaten to make these communities unlivable for some animals, destabilizing their finely tuned habitats.
The waters surrounding Antarctica, known as the Southern Ocean, are expected to warm by an average of 0.7˚ F by 2099. Researchers from the British Antarctic Survey investigated how the distributions of nearly 1,000 marine bottom-dwelling invertebrates will react to ocean warming over the next century. Their findings were published in a paper in Nature Climate Change last month.
You probably wouldn’t notice a 0.7˚ change in air temperature, but these organisms are perfectly adapted to tolerate a very specific temperature range. For them, this small change will have significant impacts.
Surprisingly, researchers found there was no one unifying trend in how bottom-dwelling invertebrates will react to the increase in temperature.
While they found that 54% of animals surveyed (963 species) were expected to lose habitat, they also found that significant extinctions are unlikely to result from warming on its own. In fact, 46% of species are likely to gain habitat. An area too hot for one animal may be just right for another.
Antarctic creatures gaining habitat may seem like good news, but the actual impacts aren’t so cut and dry.
“Shrinking is almost always a bad thing, but expanding their ranges isn’t always a good thing,” said Huw Griffiths, a biogeographer at the British Antarctic Survey and leader of the study.
Species that had been separated by temperature barriers for millions of years will be suddenly competing for the same resources. When resources are limited, one species will outcompete the other, leading to local extinctions.
“You could completely change the entire ecosystem,” Griffiths said.
Most concerning for Griffiths, the effects of warming are likely to combine with other factors resulting in potentially devastating consequences. “These combined threats are probably the biggest issue,” Griffiths said.
The chemistry of the ocean is directly impacted by its temperature. As waters warm, they tend to become more acidic. Acidic waters make it harder for animals to build skeletons and shells, leaving them vulnerable and unable to develop.
While animals may be able to deal with temperature changes, “if you throw in ten other things for them to cope with at the same time, then you may push some of them over the edge even though our temperature model may not say that’s going to make them go extinct locally or globally,” Griffiths said.
Though the Antarctic is distant from human civilization, its physical and biological functions are vitally important to people and animals globally.
“The Southern Ocean really is the lungs of the planet,” said Andrew Meijers, a physical oceanographer at the British Antarctic Survey. “It regulates how much carbon stays in the atmosphere. It regulates how much heat gets put into the ocean.”
Cold water is able to absorb more carbon, so as the Antarctic gets warmer, its ability to absorb carbon and heat will be reduced. This means that huge inputs of energy that were mitigated by this exchange will remain in the atmosphere, resulting in higher global temperatures and more carbon air pollution.
These changes could mean humans miss out on important scientific data. “If [the Antarctic environment] rapidly changes over the next 50 or 100 years, there’s large chunks of it we won’t get to see or understand,” Meijers said.
This could mean losing information on the important physical functions of Antarctica as well as missing medical opportunities. Antarctic animals’ unique chemical defenses are currently being investigated as a promising new area of antibiotic and other medical research.
As climate models become more precise and more biological information becomes available, the researchers hope to expand their analysis to determine exactly how these secondary threats will impact Antarctic invertebrate distribution.
“We’ve only just kind of opened the door on this one a little bit and just tried one thing,” Griffiths said. “One of the fundamentals of science is: it’s never done.”