Meta-analysis reveals an extreme “decline effect” in the impacts of ocean acidification on fish behavior

Rising ocean acidity unlikely to affect fish behaviour

28 July 2022

Despite the predictions of early studies, fish behaviour is unlikely to be affected by the rising acidity of the oceans.

Seawater is becoming more acidic due to increasing carbon dioxide levels in the atmosphere. Studies that simulated ocean acidification in the lab and that were published in prestigious journals in 2009 and 2010 sounded alarm bells that this would greatly affect fish behaviour. But subsequent studies have failed to reproduce their results.

Now, four researchers, including one from Deakin University in Australia, have reviewed 91 studies of empirical tests of ocean acidification on fish behaviour and found that it will have negligible direct impact.

They contend that it is a textbook case of the ‘decline effect’ in which later studies expose that early studies have often grossly overestimate a phenomenon. First described in the 1930s, this effect is driven by the bias to publish ground-breaking studies. Also, initial studies tend to have lower sample sizes.

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References

1. PLoS Biology 20, e3001511 (2022). doi: 10.1371/journal.pbio.3001511