The increasing absorption of carbon dioxide from the oceans has profound consequences. A study presented at the Society for Experimental Biology reveals a previously unknown neurological impact on cephalopods.
According to preliminary results, prolonged exposure to CO levels2 expected for 2100 would cause massive brain atrophy in squid.
How was this experiment carried out?
To measure the impact of future acidification, researchers raised bigfin reef squid (Sepioteuthis lessoniana) from hatching in two distinct environments.
The first simulated current ocean conditions, while the second reproduced a scenario predicted for 2100, with a pH lowered to 7.8 due to CO levels2 higher.
After 90 days, magnetic resonance imaging analysis revealed major physiological changes.
What are the consequences for the squid?
The study demonstrated an average reduction in 49% brain volume in squid exposed to the conditions of 2100, without any change in the overall size of their body.
The most affected areas are the optic lobes and optic tracts, essential for processing visual information, which decreased by 52% and 62% respectively.
This neurological atrophy has direct repercussions on their behavior, for example a reduction in their hunting activities. Reluctance to feed could be linked to decreased visual acuity.
What future for these intelligent invertebrates?
Cephalopods, which include squid, cuttlefish and octopuses, are considered the most intelligent invertebrates, with a number of neurons comparable to that of a dog.
Their brain atrophy due to CO2 constitutes a serious threat to their survivalby altering an essential ability: sight, which they use to track and capture their prey.
The exact mechanisms of this brain shrinkage are still being studied. Researchers suggest avenues such as oxidative damage.
