Long-term effects of contrasting pCO levels on the scope for growth in the carnivorous gastropod Concholepas concholepas.

We evaluated the effect of contrasting pCO levels: lower (390 μatm), moderate (700 μatm) and extreme (1000 μatm), on the scope for growth of the keystone snail Concholepas concholepas over an exposure period of 6 months. Juvenile snails were collected from rocky intertidal habitats and acclimated for 5 months to those pCO levels. Subsequently, three groups of snails were randomly taken (n = 7 for each treatment) and reared for an additional 1 month for each of the three pCO levels. Physiological traits related with energy gain and energy expenditure were quantified. The scope for growth index decreased significantly with increases in pCO, yielding negative values throughout the experimental period for the snails exposed to 1000 μatm pCO, probably due to the extra energy required to maintain their metabolic functions in balance. This suggests that future climate change scenarios with elevated pCO levels could threaten the growth and other basic functions of juvenile snails of this species.