Elevated CO2 affects shell dissolution rate but not calcification rate in a marine snail

Area of Science:

• Marine Biology
• Oceanography
• Chemical Oceanography

Background:

• Atmospheric carbon dioxide (CO2) levels are rising, leading to increased CO2 absorption by oceans.
• Ocean acidification, characterized by lower pH and reduced calcium carbonate saturation, can affect marine calcifying organisms.
• The differential impact of elevated CO2 on shell deposition versus dissolution rates is not well understood for many marine species.

Purpose of the Study:

• To investigate the effects of projected future carbon dioxide (CO2) levels on shell deposition and dissolution rates.
• To determine the relative impact of ocean acidification on shell formation and degradation in a marine snail.

Main Methods:

• Experimental manipulation of CO2 levels to simulate future ocean conditions (100 and 200 years).
• Measurement of daily shell weight gain in live Nucella lamellosa snails.
• Measurement of daily shell weight loss in empty Nucella lamellosa shells.

Main Results:

• Shell weight gain per day in live snails showed a linear decrease with increasing CO2 levels.
• Simultaneously, empty shells exhibited a parallel increase in daily weight loss with rising CO2.
• This suggests that increased shell dissolution, not reduced deposition, is the primary driver of net shell weight changes.

Conclusions:

• Ocean acidification may disproportionately affect shell dissolution rates compared to deposition rates in marine molluscs.
• The findings highlight a significant vulnerability of shell integrity in species like Nucella lamellosa to future ocean conditions.
• Temperate marine molluscs may experience greater negative impacts from shell dissolution due to ocean acidification.