The updated ocean acidification indicator shows there has been a decrease in the pH of Aotearoa New Zealand’s subantarctic surface waters as they have become more acidic, Stats NZ said today.
Between 1998 and 2020, ocean acidity in Aotearoa New Zealand’s subantarctic surface waters increased 8.6 percent corresponding to a pH decrease from 8.092 to 8.057. Because the pH scale is logarithmic, small changes in pH represent large changes in acidity. Changes in pH in the open ocean are primarily influenced by absorption of atmospheric carbon dioxide by seawater.
Acidification of the seawater reduces the shell- or skeleton-building ability of many marine organisms such as plankton, coastal algae, crustaceans, echinoderms, and molluscs such as pāua and kuku (green-lipped mussel). This may affect the survival, growth, and reproduction of these species. As many of these species form the base of the marine food chain, ocean acidification may cause widespread harm to ecosystems in our coastal waters and oceans.
More information, along with data from Aotearoa New Zealand’s subantarctic waters and coastal sites, can be found on the Ocean acidification indicator page.
