Ideas and perspectives: When ocean acidification experiments are not the same, repeatability is not tested

Abstract

Abstract. Can experimental studies on the behavioural impacts of ocean acidification be trusted? That question was raised in early 2020 when a high-profile paper failed to corroborate previously observed responses of coral reef fish to high CO2. New information on the methodologies used in the “replicated” studies now provides a plausible explanation: the experimental conditions were substantially different. High sensitivity to test conditions is characteristic of ocean acidification research; such response variability shows that effects are complex, interacting with many other factors. Open-minded assessment of all research results, both negative and positive, remains the best way to develop process-based understanding. As in other fields, replication studies in ocean acidification are most likely to contribute to scientific advancement when carried out in a spirit of collaboration rather than confrontation.

Paths towards greater consensus building in experimental biology

“…More recent studies have cast doubt on the severity and universality of acidification effects on fish behaviour (Clark et al, 2020a), and a decade of work in the field exhibits signs of a 'decline effect', whereby the strong initial effect sizes reported in early studies have all but disappeared over the past 5 years (Clements et al, 2022). The extent and degree to which aquatic acidification affects the behaviour of ectotherms remains a debate in the field (Clark et al, 2020b;Munday et al, 2020;Williamson et al, 2021).…”

“…For example, debates about the OCLTT, GOL and OA-driven behavioural change, among others, have led to stalemates rather than efforts by interested parties to seek consensus (e.g. Clark et al, 2020a;Munday et al, 2014b;Pörtner et al, 2018;Williamson et al, 2021). Various reasons might explain this outcome, and the failure of debates to achieve a constructive and open-minded tone is not unique to these examples, this generation of scientists, or to the natural sciences specifically (e.g.…”

Insight into real-world complexities is required to enable effective response from the aquaculture sector to climate change

“…Behaviour had a 'Potential link' to 1 climate stressor (Ocean acidification). The impact of ocean acidification on fish behaviour is a source of debate amongst researchers [143], and there is a need for further work on salmon.…”

Elevated CO2 does not alter behavioural lateralization in free‐swimming juvenile European sea bass (Dicentrarchus labrax) tested in groups

“…Other work has shown no effect of OA on fish behaviour ( e.g ., Clark et al ., 2020). Differences in species and context studied, and methodology used, may explain these different findings (Munday et al ., 2020; Williamson et al ., 2021).…”