Climate Change on marine Ecosystems monitored by radioisotopes: The REMO/ClimOcean project at SPES/LNL RIB facility

Abstract

Almost one quarter of human-caused carbon dioxide (CO 2 ) emissions are absorbed by oceans, resulting in ocean acidification, i.e. a decrease in the ocean water pH. The large amount of CO 2 molecules was released to the atmosphere during industrial revolution, starting from 170-280 parts per million in the XIX century up to 418 parts per million in 2023. Oceans absorbed about 22% of this anthropogenic CO 2 between 2008-2017. Carbon dioxide reacts with water producing carbonic acid (H 2 CO 3 ), which lowers the pH, producing ocean acidification. The latter, combined with global warming, has a vast anthropogenic effect on marine ecosystems, influencing negatively the physiology and ecology of marine ecosystems. Coral communities are particularly affected by rapid changes in the ocean conditions. As coral, echinoderms and bivalve mollusks build their exoskeletons and shells respectively through the production of calcium carbonate (CaCO 3 ), the influence of seawater acidification on the Calcium uptake of these organisms can be significant. The REMO/ClimOcean project, granted within the Next Generation EU program, focuses on the study of marine species heavily impacted by acidification. Calcification rates are determined using stable and radioactive isotopes (radiotracers) for different species of corals, sea urchins and bivalves, comparing animals grown at present and projected pH values. Measurements have been performed at the Oceanografic and IFIC-CSIC Valencia, Spain, at the Hydro-biological station in Chioggia, Italy and at the island of Ischia, Italy.