Chemical aspects of ocean acidification monitoring in the ICES marine area

• Main Authors: Borges, Alberto, Borges C, Greenwood N, Hartman SE, Hydes DJ, Kivimae C, McGovern E, Nagel K, Olafsdottir S, Pearce D, Sahlsten E, Rodriguez C, Walsham P, Webster L
• Other Authors: FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
• Format: Report
• Language: English
• Published: International Council for the Exploration of the Sea 2013
• Subjects: Life sciences; Aquatic sciences & oceanology; Sciences du vivant; Sciences aquatiques & océanologie; Northeast Atlantic; Ocean acidification
• Online Access: https://orbi.uliege.be/handle/2268/295724; https://orbi.uliege.be/bitstream/2268/295724/1/CRR319.pdf

It is estimated that oceans absorb approximately a quarter of the total anthropogenic releases of carbon dioxide to the atmosphere each year. This is leading to acidification of the oceans, which has already been observed through direct measurements. These changes in the ocean carbon system are a cause for concern for the future health of marine ecosystems. A coordinated ocean acidification (OA) monitoring programme is needed that integrates physical, biogeochemical, and biological measurements to concurrently observe the variability and trends in ocean carbon chemistry and evaluate species and ecosystems response to these changes. This report arises from an OSPAR request to ICES for advice on this matter. It considers the approach and tools available to achieve coordinated monitoring of changes in the carbon system in the ICES marine area, i.e. the Northeast Atlantic and Baltic Sea. An objective is to measure long-term changes in pH, carbonate parameters, and saturation states (Ωaragonite and Ωcalcite) in support of assessment of risks to and impacts on marine ecosystems. Painstaking and sensitive methods are necessary to measure changes in the ocean carbonate system over a long period of time (decades) against a background of high natural variability. Information on this variability is detailed in this report. Monitoring needs to start with a research phase, which assesses the scale of short-term variability in different regions. Measurements need to cover a range of waters from estuaries and coastal waters, shelf seas and ocean-mode waters, and abyssal waters where sensitive ecosystems may be present. Emphasis should be placed on key areas at risk, for example high latitudes where ocean acidification will be most rapid, and areas identified as containing ecosystems and habitats that may be vulnerable, e.g. cold-water corals. In nearshore environments, increased production resulting from eutrophication has probably driven larger changes in acidity than CO2 uptake. Although the cause is different, data are ...