Table_1_Toward a Mechanistic Understanding of Marine Invertebrate Behavior at Elevated CO2.DOCX

Elevated carbon dioxide (CO₂) levels can alter ecologically important behaviors in a range of marine invertebrate taxa; however, a clear mechanistic understanding of these behavioral changes is lacking. The majority of mechanistic research on the behavioral effects of elevated CO₂ has been done in fish, focusing on disrupted functioning of the GABA_A receptor (a ligand-gated ion channel, LGIC). Yet, elevated CO₂ could induce behavioral alterations through a range of mechanisms that disturb different components of the neurobiological pathway that produces behavior, including disrupted sensation, altered behavioral choices and disturbed LGIC-mediated neurotransmission. Here, we review the potential mechanisms by which elevated CO₂ may affect marine invertebrate behaviors. Marine invertebrate acid–base physiology and pharmacology is discussed in relation to altered GABA_A receptor functioning. Alternative mechanisms for behavioral change at elevated CO₂ are considered and important topics for future research have been identified. A mechanistic understanding will be important to determine why there is variability in elevated CO₂-induced behavioral alterations across marine invertebrate taxa, why some, but not other, behaviors are affected within a species and to identify which marine invertebrates will be most vulnerable to rising CO₂ levels.