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Led by researchers from Acadia University and Academia Sinica, this preliminary study shows that a simple drop in pH?in line with projections for 2100?could reduce the brain size of these cephalopods, which are known for their intelligence, by nearly half.
A brain reduced by 49% under simulated conditions
To simulate future ocean conditions, scientists raised squid (Sepioteuthis lessoniana) from the moment they hatched in two distinct environments: one tank with the current pH (8.2) and a second with a pH of 7.8, corresponding to climate projections for the end of the century.
After 90 days, imaging studies revealed a striking result: individuals exposed to acidified water had brains that were 49% smaller than those of the control group. However, their physical growth remained similar, ruling out a simple developmental delay.
A pH difference of just 0.4 is therefore enough to cause a major change in the brain?a finding that surprised even the researchers themselves.
Vision on the Front Lines
Not all areas of the brain are affected in the same way. The regions associated with vision appear to be particularly vulnerable:
- The optic lobes lose up to 52% of their volume.
- The optic tracts, which are essential for the transmission of visual information, are reduced by 62 percent.
However, these structures play a key role in detecting and capturing prey. Such damage could therefore significantly compromise the squid's hunting efficiency.
A Major Environmental Challenge
These findings raise serious concerns. Squid are among the most intelligent marine invertebrates, with a neuron density comparable to that of certain vertebrates, such as dogs.
A decline in their sensory and cognitive abilities could have a ripple effect on marine food chains, where they play a central role as both predators and prey.
While this research has yet to be confirmed, it provides concrete evidence of the potentially profound effects of ocean acidification on the behavior and survival of marine species.
Yet another warning sign for marine ecosystems, which are already vulnerable due to climate change.
