Scientists warn shrinking fish could be an early sign of something worse

What makes a new global study on marine life particularly significant is that it demonstrates, for the first time on a truly global scale, that ocean warming leaves a distinct fingerprint on marine animals, one that is both stronger and more erratic than the effects of other environmental crises, and one that has held steady across hundreds of millions of years of Earth’s history.

Researchers built one of the largest collections of marine body size data ever assembled, drawing on almost 9,000 recorded changes and over 1.6 million measurements from fossils, historical records and living animals. Sea creatures shrank far more sharply during periods of intense global warming compared to crises caused by cooling or falling oxygen levels, a pattern paleontologists call the ‘Lilliput effect.’

Paulina S Nätscher, the paleobiologist who led the study at Friedrich Alexander Universität Erlangen Nürnberg in Germany, found that warming-linked crises produced shrinking effects roughly twice as strong as other kinds of disasters. The bigger the temperature jump, the steeper the drop in body size tended to be.

Researchers suggest animals will likely keep shrinking as ocean temperatures continue climbing, until warming eventually stops merely stunting growth and starts pushing species toward extinction altogether. The findings have been published in the Proceedings of the National Academy of Sciences.

Image: Wikimedia Commons/by Xplore Dive