The oceans absorb about 25% of human-produced CO₂ each year, driving ocean acidification by altering seawater chemistry. Since the industrial revolution, ocean acidity has increased by ~30% and is expected to rise further, with possible acceleration under continued emissions. Coastal processes such as riverine alkalinity inputs and nutrient enrichment can modulate local acidification, sometimes intensifying seasonal fluctuations.
Ocean acidification, alongside ocean warming, poses a major threat to marine ecosystems. Shell-forming organisms, including commercially important shellfish, are particularly at risk because reduced carbonate availability can impair calcification, weaken shells, and increase dissolution. These impacts can raise physiological stress by increasing the energy needed for growth and regulation. Early life stages are especially sensitive, affecting survival and population stability, which creates concerns for shellfish aquaculture.
This project will use high-resolution microCT scanning (Zeiss Xradia Versa 620) to analyse shell structure in key bivalve species across Irish waters, including Mytilus edulis, Ostrea edulis, Magallana gigas, and Ruditapes philippinarum. Specimens will be collected from environments representing a range of carbonate conditions. Advanced image analysis will enable detailed 3D modelling of shell structure, allowing quantification of density and integrity to assess organism health.
The study will also examine shell growth patterns to compare populations across different fisheries. Where available, archived shell material will be analysed alongside contemporary samples to investigate long-term changes, taking advantage of the non-destructive nature of microCT imaging. Together, these analyses aim to improve understanding of how ocean acidification and related stressors influence shell formation and the resilience of marine shellfish populations.
- Marine molluscs are keystone species in Irish coastal waters and of high commercial value. With reports of reduced recruitment and condition for some mollusc species, it is critical to understand the current and future impacts of climate change and ocean acidification. This study will provide a key baseline study to evaluate how shell structure may respond to acidification, as an early warning.
- Ocean Acidification has been identified as a substantial risk mid-century in the National Climate Change Risk Assessment (EPA 2025) and the risk has also been flagged in the Agriculture, Forest and Seafood Climate Change Sectoral Adaptation Plan. Ultimately these impact assessments will contribute to risk assessment and adaptation planning.
This project runs from 2025 to 2028
The project objectives are to deliver:
- Technical Note, detailing the application, and workflow to assess mussel fitness using the Zeiss Xradia Versa 620.
- A novel baseline dataset on shell morphology and image library
- A report describing the key finding of analysis of the images, considering species, life cycle stage and linked to information on local carbonate system conditions as available
- Any recommendations for incorporation of microCT scanning of shell structure in future monitoring as a potential impact indicator of Ocean acidification