A Better World - Volume 6

[ ] 68 A Bet ter Wor ld Monitoring of the ocean acidification crisis, and intervention to combat climate change through adaptation of coral reefs Dr. Nobuko Nakamura, Research Fellow; Dr. Atsushi Watanabe, Senior Research Fellow, The Ocean Policy Research Institute of the Sasakawa Peace Foundation D ubbed by some researchers as the evil twin of climate change, ocean acidification (OA) is expected to have an unfavourable impact on calcifying organ- isms such as molluscs and reef-building corals. Coral reefs are seriously threatened by climate change, especially by warming, such that recovery intervention options should be pursued in tandem with mitigation measures. Such chal- lenges are prevalent around Japan and the Pacific islands. Ocean acidification is a result of increasing CO 2 in the atmosphere, and is most pronounced where temperatures are lowest, such as in the polar regions, or where CO 2 -rich water is brought to the ocean surface by upwelling. 1 Acidification can also be influenced by the presence of effluent from natural or disturbed coastal land use 2 , plankton blooms 3 , and the atmospheric deposition of acidic materials 4 . These sources may not be directly attributable to climate change, but they may amplify the impacts of ocean acidification. 5 Ocean acidification due to increased CO 2 has resulted in a 0.1 pH unit (hydrogen ion exponent) decrease since the pre-industrial period, representing a change unprecedented in the last 65 million years. At present, marine ecosystems, especially coral reefs and polar ecosystems, are at risk from acidification. Highly calcified molluscs, echinoderms and reef-building corals are more sensitive to environmental change than are crustaceans and fish. From the IPCC AR5 future prediction, the impacts on individual species and the number of species affected in species groups increase from RCP4.5 to RCP8.5. 6 Ocean acidification acts together with other global changes, for instance warming and progressively lower oxygen levels, and with local changes such as pollu- tion and eutrophication, leading to interactive, complex and amplified impacts on species and ecosystems. 6 Among measures to address these problems, the establish- ment and cooperation of international monitoring networks are being promoted. Also, in each country, integrated coastal management (ICM) and the mitigation of greenhouse gas emissions are being called for. At the same time, promotion of public awareness about ocean acidification is important. The Japanese case As a member of The North Pacific Marine Science Organ- ization (PICES), Japan is contributing to summarizing information on the present status of pH measurement among Pacific countries, including methods of measurement and calibration that vary with each monitoring environment, making comparison difficult. In Japan several investigators have voluntarily convened a Japan Ocean Acidification Network (JOAN) as a platform for information exchange and collaboration in measure- ment and analysis. Information from 10 coastal monitoring sites is currently reported to PICES, with several stations having been incorporated into the global Ocean Acidification Observing Network (GOA-ON). 7 Using water quality data collected at 289 monitoring sites in Japan between 1978 and 2009 as part of the Water Pollution Control Programme, the long-term trends of in-situ pH in the coastal seawater were evaluated at ambient temperature. It was found that the annual maximum in-situ pH had decreased at 75 per cent of the sites but increased at the remaining 25 per cent. Nevertheless, it is thought that the ICM concerning anthropogenic eutrophication around the coastal landscape has high potential to regulate coastal acidification. 8 However, ocean acidification cannot be evaluated simply by pH value as shown by the carbonate equilibrium in the ocean. Another parameter of carbonate chemistry concern- International network for ocean acidification monitoring IAEA Ocean Acidification International Coordination Center (OA-ICC) The International Ocean Carbon Coordination Project (IOCCP) European Project on Ocean Acidification (EPOCA) IOC-UNESCO Global Ocean Observing System (GOOS) Global Ocean Acidification Observation Network (GOA-ON) (Around Pacific Region) The North Pacific Marine Science Organization (PICES) IOC-UNESCO Sub-Commission for the Western Pacific (WESTPAC) Pacific Islands & Territories Ocean Acidification(PI-TOA) Network New Zealand Ocean Acidification Observing Network (NZOA-ON)