Intertidal oysters reach their physiological limit in a future high-CO2 world
Elliot Scanes1,2, Laura M Parker2, Wayne A O'Connor3
1School of Science and Health, Western Sydney University, Penrith, NSW 2750, Australia elliot.scanes@sydney.edu.au.
The Journal of Experimental Biology
|March 3, 2017
Summary
High CO2 levels and tidal emersion negatively impact oyster physiology, reducing their ability to survive in intertidal zones. This suggests future ocean acidification may lower oyster distribution limits.
Area of Science:
- Marine Biology
- Oceanography
- Physiology
Background:
- Intertidal molluscs face internal acidosis during air exposure.
- Molluscs are vulnerable to ocean acidification, yet some show resilience to high CO2.
- Previous studies may underestimate CO2 impacts without tidal simulations.
Purpose of the Study:
- To predict the future intertidal limit of oysters under high CO2 conditions.
- To test if regular acidosis enhances tolerance to elevated PCO2 in high-shore oysters.
- To determine if elevated PCO2 pushes high-shore oysters to their physiological limits.
Main Methods:
- Sydney rock oysters (Saccostrea glomerata) from high-intertidal and subtidal zones were used.
- Oysters were subjected to simulated intertidal or subtidal treatments under ambient or elevated PCO2.
- Physiological variables, including haemolymph pH, PCO2, metabolic rate, condition, and growth, were measured.
Main Results:
- Combined tidal emersion and elevated PCO2 synergistically decreased haemolymph pH (pHe) and increased haemolymph PCO2 (Pe,CO2) and metabolic rate.
- Oysters in the intertidal treatment exhibited lower condition and growth rates.
- Intertidal oysters showed plasticity but were not more resilient than subtidal oysters.
Conclusions:
- Elevated PCO2 and tidal emersion negatively impact oyster physiology.
- Oyster resilience to high CO2 is limited, contrary to some previous findings.
- The upper vertical distribution limit of oysters may decrease in a high-CO2 ocean, with potential underestimation in prior studies lacking tidal simulations.
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