CHRONIC EXPOSURE OF A FRESHWATER MUSSEL TO ELEVATED pCO2: EFFECTS ON THE CONTROL OF BIOMINERALIZATION AND ION-REGULATORY RESPONSES

Abstract

Freshwater mussels may be exposed to elevations in pCO₂ due to both natural and anthropogenic factors. The goal of the present study was to assess the effects of a 28-d elevation in pCO₂, at 15,000 and 50,000 µatm, on processes associated with biomineralization, ion regulation, and cellular stress in adult Lampsilis siliquoidea (Barnes, 1823). In addition, the capacity for mussels to compensate for acid-base disturbances experienced following exposure to elevated pCO₂ was assessed over a 14-d recovery period. Overall, exposure to 50,000 µatm pCO₂ had more pronounced physiological consequences compared to 15,000 µatm pCO₂. Over the first 7 d of exposure to 50,000 µatm pCO₂, the mRNA abundance of chitin synthase (cs), calmodulin (cam), calmodulin-like protein (calp) were significantly affected, suggesting that shell formation and integrity may be altered during pCO₂ exposure. Following the removal of the pCO₂ treatment, mussels may compensate for the acid-base and ion disturbances experienced during pCO₂ exposure, and transcript levels of some regulators of biomineralization (carbonic anhydrase, ca; cs, cam, calp) as well as ion regulation (na⁺-k⁺-ATPase, nka) were modulated. Effects of elevated pCO₂ on heat shock protein 70 (hsp70) were limited in the present study. Overall, adult L. siliquoidea appeared to regulate factors associated with the control of biomineralization and ion regulation during and/or following the removal of pCO₂ exposure. This article is protected by copyright. All rights reserved

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