• This dataset illustrates how local carbonate chemistry can vary widely along short lengths of coastline due to local drivers, particularly bedrock geology.
• Results highlight which season is most/least favourable for calcifying species and how this relates to their lifecycle.
• The dataset identified a number of key issues when addressing indicators of ecosystem vulnerability (calcium in omega calculations and SIR-).
• Results illustrate that we must understand both regional and local conditions in order to estimate future ocean acidification conditions and potential impacts on local ecosystems and shellfish aquaculture.
Four contrasting coastal systems in Ireland, each with shellfish production activities, were studied to provide a first evaluation of the spatial and seasonal influences on the local carbonate system. The study sites included; (1) a coastal system with sandstone bedrock and minimal freshwater sources, (2) an estuarine system with a catchment limestone bedrock, (3) an estuarine system with a catchment granite bedrock, and (4) a karst groundwater-fed estuary. The type of bedrock was the dominant control on regional carbonate chemistry, where the calcium carbonate catchment bedrock was a strong source of both dissolved inorganic carbon and total alkalinity input in the two limestone regions, which are supersaturated with respect to atmospheric CO2 throughout the year. Primary production played an important role in the non-limestone regions, where both systems were CO2-undersaturated during productive months. Minimum aragonite saturation () was observed at all sites during winter when productivity is lowest; surface winter is 2 in the inner estuary. The substrate-to-inhibitor ratio (SIR), an alternative indicator of ecosystem vulnerability to acidification, was positively correlated to in all systems, however with more variability in the two limestone regions. Results highlight challenges of assessing local ecosystem vulnerability to future acidification and the importance of understanding the local spatio-temporal biogeochemistry.
McGrath T., McGovern E., Gregory C. & Cave R. R., in press. Local drivers of the seasonal carbonate cycle across four contrasting coastal systems. Regional Studies in Marine Science. Article (subscription required).