Coping with carbon: the inherited effects of climate change in reef fish

An international team lead by Timothy Ravasi of Saudi Arabia’s King Abdullah University of Science and Technology (KAUST) measured gene expression in the brains of three groups of spiny damselfish. One group had been raised in water with current CO₂ levels and then exposed to predicted end-of-century CO₂ levels for four days; the second and third group were raised in water with end-of-century CO₂ levels, but the parents of the third group had also lived in the same environment. 

In all three groups, elevated CO₂ led to changes in genes linked with glucose metabolism, suggesting that this may be a key pathway for fish to adapt to the predicted changes in their environment. Fish raised in elevated CO₂ concentrations also had changes in the expression of genes involved in epigenetic regulation and the GABA neurotransmitter pathway. However, this was only true if their parents had lived in a normal CO₂ environment, and it also depended on whether the parents had a genetic predisposition to elevated CO₂ tolerance. 

“The environment during development is important, but it seems to a certain extent that previous parental exposure buffers the molecular reaction needed during development,” says Celia Schunter, the study’s lead author. Overall, “things are looking pretty grim for the spiny damselfish,” says Schunter, though she holds out hope that tolerant individuals may enable the species to adapt. 

Next, the team plans to identify the genomic regions behind CO₂ tolerance and to confirm their findings in Papua New Guinea, where fish are naturally exposed to excess CO₂ seeping from volcanic vents.

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