Climate change may cause an increase in squid populations
Climate change already appears to be responsible for an overabundance of jellyfish in the world's oceans, but new research indicates that it may also lead to something else – lots and lots of squid. The findings run contrary to what was expected to be the case.
As global warming causes the seas to warm, increased carbon dioxide content in the water causes it to become more acidic. Squids' blood is very sensitive to changes in acidity, so it had been thought that ocean acidification would negatively affect their aerobic performance. As it is, the animals' swimming technique is very energy-intensive, requiring a great deal of oxygen to be absorbed and transported by their cardiovascular system.
To test how well they might fare in the future, scientists at Australia's James Cook University placed multiple two-toned pygmy squid and bigfin reef squid in continuous-flow water tanks, and kept the two species there for a period equivalent to approximately 20 and 36 percent of their lifespans, respectively. The CO2 concentration of the water had been raised to a level that is expected for the world's oceans, by the end of the century.
Surprisingly, even after performing "exhaustive exercise" for sustained periods, the cephalopods' aerobic performance and recovery remained unaffected. This adaptability was thought to be due to better-than-expected blood oxygen binding, and it could not only allow squids to survive climate change, but it may even result in a population boost – some of their key predators have been proven to be negatively affected by acidification.
"We think that squid have a high capacity to adapt to environmental changes due to their short lifespans, fast growth rates, large populations, and high rate of population increase," says lead scientist Dr. Blake Spady. "We are likely to see certain species as being well-suited to succeed in our rapidly changing oceans, and these species of squid may be among them. The thing that is emerging with most certainty is that it's going to be a very different world."
A paper on the research was recently published in the journal Conservation Physiology.