Study Reveals Marine Animals Are Shrinking Due to Climate Change

Climate change is not only raising ocean temperatures but also triggering a shrinkage in the body size of marine animals. The finding comes from research that analysed changes in the size of marine organisms over approximately 450 million years and shows the phenomenon becomes more extreme during periods of global warming. The study, conducted by Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), the University of Warsaw, and the University of Lille, found that various marine animals, such as shellfish, crustaceans, and fish, tend to shrink when facing environmental crises. The phenomenon, known as the Lilliput effect, is considered one of the biological responses to environmental pressure. The research team analysed nearly 9,000 data points on changes in marine animal body size derived from fossil records, historical records, and modern observations. The results, published in the journal Proceedings of the National Academy of Sciences, show that global warming is a factor that intensifies the shrinkage of marine organism body size. “Our data show that body size decline is a common response of marine animals to environmental crises. We observed this phenomenon across a wide variety of animal groups, from dwarfism in specific species to the dominance of small-sized species across entire ecosystem communities. Body size shrinkage is a strong signal that an ecosystem is under severe stress,” said lead author Paulina Nätscher, as quoted from Phys.org. Kenneth De Baets, a researcher from the University of Warsaw, explained that body size shrinkage occurs in almost all environmental crises. However, the impact becomes much greater when the crisis is triggered by rising global temperatures. “In all environmental crises, whether triggered by warming temperatures or not, body size shrinkage definitely occurs within biological communities,” Kenneth said. According to him, extreme global warming triggers greater changes in body size at the species level. “However, what is most striking is that crises with extreme global warming trigger much stronger and more varied changes directly within the species themselves, or in other words, trigger real dwarfism. On average, the impact of this shrinkage is twice as severe during warming phases compared to other environmental crises,” he said. Wolfgang Kießling, Head of the Palaeoenvironmental Analysis Unit at FAU, said the link between rising temperatures and the shrinking body size of marine animals is very clear in the Earth’s historical record. “The higher the Earth’s temperature rises, the more extreme the shrinkage of marine animal body size. Earth’s history thus provides a stark warning for the future of our oceans,” Wolfgang said. The study concludes that the trend of shrinking fish and marine invertebrates now being observed in various regions is not merely a temporary phenomenon, but part of a pattern that has repeated throughout Earth’s geological history. If global warming continues, smaller body sizes of marine organisms are expected to become an increasingly common condition and could potentially affect marine food chains and global fisheries productivity.