Acidifying oceans may endanger the development of the squid. According to a study by the American Woods Hole Oceanograpic Institution (WHOI). Because the species is ecologically and commercially important, this may have major consequences for the environment of the ocean and the economy on the coast.
“Squid are central to the ocean's ecosystem. Almost all animals eat or are eaten by this squid. If something happens to this animal species, it has consequences for the entire food chain, ”says T. Aran Mooney, one of the researchers.
For the past 150 years, the world's oceans have been steadily souring. This is due to the rising amount of carbon dioxide in our atmosphere. Seawater absorbs part of this carbon dioxide and turns it into carbonic acid and other chemical by-products that lower the pH of the water and thereby make it more acidic. As the carbon dioxide in the atmosphere continues to rise, scientists think that the oceans will become even more acidic and that more animals are at risk.
One of those species is the squid, the research now shows. In the summer of 2011 the team collected both male and female squids and placed them in a tank. Then we had to wait for the mating of the animals, which can lay 200 to 300 fertile eggs. The eggs were then placed in two different tanks. One had to represent the ocean today and the other the more soured ocean in the future. The researchers then watched as the eggs hatched and developed into squids. They measured the duration of the hatching eggs, the height of the body and other values.
Remarkably, the team noted changes in all measured values. Cuttlefish in the tank that was to represent the ocean of the future took longer to develop. And this is not a good sign according to Mooney. "In the real ocean every fish could come by and eat the eggs." In addition, the squids in the even more acidic water turned out to be five percent smaller than average. But what can really jeopardize the squid is the greater chance of a malformed statocyst: an organ that helps the animal orient. Earlier research shows that squid with this abnormality often swim in circles or poorly, this increases the risk of death because they cannot escape their hunters or catch their prey.
The results suggest that the species is vulnerable to acid conditions due to high carbon dioxide levels, and now that the oceans are becoming more acidic, there is an even greater challenge to survive. If development continues, this has direct consequences for both the ecosystem and the economy. Cuttlefish are the food source for many species of commercially important fish such as tuna. The species of squid itself is also prey for humans: in 2011, American fishermen caught more than 300 million pounds of squid with a value of more than 100 million dollars.
The team is now planning further investigations. The scientists also want to investigate the consequences of global warming for squid.