Past, present, and future of nuclear technique application for ocean acidification research

Sammanfattning

Oceans have absorbed a significant part of the anthropogenic carbon dioxide (CO2), causing rapid changes in the marine environment and a decline in surface water pH. While the effects of Ocean acidification (OA) are well known for certain organisms, many of its impacts remain under-researched. Nuclear techniques can offer a powerful tool for studying the adverse effects of OA on many biological processes yet to be understood. This thesis analyses the implementation of nuclear techniques used to study direct biological responses in 115 scientific articles within the field, to identify its potential and limitations going forward. A semiquantitative overview was achieved by evaluating the quantity and quality of scientific articles, frequency of techniques used, investigated organisms, geographical distribution, and estimated parameters. Despite recognizing a positive trend in nuclear technique application, it still constitutes a small portion of the overall OA research. Eight nuclear techniques (11B, 13C, 14C, 45Ca, 18O, 15N, 3H, and trace elements) were to varying degrees included in the articles, with 13C being the most common. They generally provided sensitive measurements of parameters otherwise difficult to pinpoint, like for example calcification rates, internal pH and carbon acquisition mechanisms. However, three major challenges need to be addressed. First, methodological and analytical disagreements prevail, often due to complex isotopic fractionation processes. Second, studies incorporating nuclear techniques are disproportionately distributed regarding geographical location, focused to a large degree around countries in global north. Third, research is primarily directed towards species of phytoplankton and calcifying organisms. It is evident that OA can have very different effects depending on factors like experimental design, location, and species. Therefore, it is necessary to broaden the scope of research and to continue reviewing the application of nuclear techniques within OA.