Save the squid: CO2 increases threaten key species in marine food chain

Man-made CO2 changes the ocean’s acidity, as it dissolves into carbonic acid and alters the pH of the waters. This higher acidity appears to have clear, detrimental effects on squid hatched and raised in it; they are smaller, and many show mutations of the crystal formations that allow them to orientate themselves whilst swimming and to detect movement. Threats to the survival of the Altantic longfin squid, which eats or is eaten by many of the ocean’s animals, have immense implications up and down the ocean food chain. It is an economically valuable species, bringing in $100 million for US fishermen in 2011; it is also food for species such as tuna and hake, other commercially important species.

Marine reserves and catch limits are possible measures that could help species survive, but the CO2-driven change in ocean acidity has bigger implications. In evolutionary terms, 100 years is a very short window. If ocean chemistry changes this significantly, this rapidly, the creatures who depend on it will struggle to adapt and it is difficult to predict what the net result will be.