Acidification varies across space and time, which is why MACAN is developing a tool for coastal stakeholders to interpret the vulnerability to acidification at a given location. This project will create a map layer to display ocean and coastal acidification indicators on the Mid-Atlantic Regional Council on the Oceans (MARCO) Ocean Data Portal. This layer will allow viewers to see where acidification may be occurring, and which species are likely to be impacted over time. Stakeholders who want to anticipate, plan for, and adapt to acidification will find this information particularly useful.

At risk locations are locations where carbonate chemistry conditions, including pH, CO2, and saturation state of aragonite or calcite needed by shell-building organisms, are severe enough to impact marine life. We provide publicly available monitoring data, including data from research cruises, moored sensors, and shore-based sampling, to analyze trends in acidification over time and identify locations where conditions surpass the sensitivity levels of local species. As we compile acidification research on sensitivity of Mid-Atlantic estuarine and oceanic species, we are also finding out which species are most important to stakeholders. This has led us to particularly focus on commercially harvested species, plants and animals that create structured habitats, and key species for ecosystem health when defining at risk location.

Review of experimental research on species responses to acidification has highlighted the differences between estuaries and the open ocean. Estuaries have greater fluctuations than the ocean in acidity and other stressors on daily to seasonal time scales. There is a greater influence of freshwater input, growth of calcifying organisms, and respiration on the carbonate chemistry parameters in estuaries. As a result, estuarine species experience greater fluctuations but may also tolerate more extreme acidification levels than oceanic species. We have also noted the importance of life stage in determining how sensitive a species is and what carbonate chemistry conditions they will be likely to experience.

To account for these factors, we will use location-specific definitions of hotspots and map hotspots on a seasonal and annual basis. The Ocean Data Portal map can accommodate this by displaying multiple categories of data at once. When users click on a hotspot, they will be able to view what data sources were used, what sensitive species the hotspot is based on, and more. This will give users a flexible experience in accessing the information that is important to them, while also being transparent as to the location-specific hotspot definitions.