Squids occupy a preponderant place in our imagination. These are the original marine monsters, immortalized in Jules Verne's classic novel Twenty thousand leagues under sea and in Scandinavian folklore, in which a cephalopod creature emerges from the sea to wreak havoc as a kraken.
The new science shows that no one should write them in the real world. They will probably be there much longer than humans, even if the planet is undergoing significant climate change.
Some marine biologists have assumed that the squid population would be affected by high concentrations of carbon dioxide. And that makes sense: squid blood is very sensitive to changes in acidity, and scientists say that creatures already live on the edge of their oxygen limits in the environment because their swimming technique consumes a lot of energy.
Now, it may be that they can actually thrive, even though other animals, including humans, are struggling to cope with global warming. This is revealed by a new study from James Cook University in Queensland, Australia.
An ocean of climate problems
Atmospheric concentrations of carbon dioxide are undeniably on the rise. Before the industrial revolution, it reached 280 parts per million (ppm). Today, that number has climbed to 400 ppm and is expected to reach more than 900 ppm by the end of the century, unless emissions are reduced. Rapid change is expected to have a profound effect on ocean ecosystems.
The carbon dioxide dissolved in the water eventually forms carbonic acid. This increased acidity could result in a damaging chain reaction to most animals. In 2017, Chinese scientists discovered that it had a negative impact on tiny cyanobacteria. These tiny creatures play a crucial role in ocean ecosystems as they perform a process called nitrogen fixation, which turns nitrogen gas into ammonia and other molecules that many organisms need.
James Cook's researchers have decided to experiment with the hope that the new policies will prevent carbon dioxide concentrations from reaching 900 ppm.
Squid takes to a new level
They picked two species of tropical calamari – two-tone pygmy squid and big-nosed reef squid – and caught them with dip nets. Back in their laboratory, the researchers separated them in different tanks with varying concentrations of carbon dioxide.
"We found that the aerobic performance and recovery of these two tropical squid species were unaffected by the highest CO2 levels predicted for the end of the century," said lead researcher Blake Spady.
The scientists speculated that the results could not only indicate that the squid would behave well in the altered ecosystem. If their predators and their typical prey are affected, it will make it easier for squid when looking for food.
"We are likely to consider that some species are well suited to succeed in our rapidly changing oceans, and these squid species can be part of it," added Spady. "The thing that emerges with the most certainty is that the world will be very different."