Global Warming Could Cause Animals to Shrink

A new study by researchers from Queen Mary’s School of Biological and Chemical Sciences has explored the possibility that many of the world’s organisms may shrink in size as a result of continued global warming.

Calanus propinquus, one of the organisms investigated in this study

This study relates to the ‘temperature-size rule’ which describes how individuals of cold-blooded organisms reach a smaller adult size when they are born and raised in a warmer climate.

The study was published in the journal The American Naturalist and authored by Dr. Andrew Hirst and colleagues from Queen Mary’s School of Biological and Chemical Sciences, thanks to funding provided by the Natural Environment Research Council.

The study was carried out using data collected over 40 years on marine planktonic copepods, tiny crustaceans that are the main animal plankton in our planet’s oceans. These little animals themselves graze on smaller plankton and are a food source for larger fish, birds and marine mammals.

The results showed that the rate at which these crustaceans grew – how fast they acquired mass – and the rate at which they developed – how fast an individual animal passes through the various stages of life – are consistently decoupled across a whole range of species, “with development being more sensitive to temperature than growth.”

“We’ve shown that growth and development increase at different rates as temperatures warm,” explains Hirst. “The consequences are that at warmer temperatures a species grows faster but matures even faster still, resulting in them achieving a smaller adult size.”

“Decoupling of these rates could have important consequences for individual species and ecosystems.”

The findings suggest that fundamental similarities between organisms such as mortality, reproduction and feeding may not change in sync with one another in a world which is continually warming. Such a change could have “profound implications for understanding how organisms work” and could eventually impact the entire food web and the planet’s ecosystems.

Source: Queen Mary University of London
Image Source: Pete Lens, British Antarctic Survey

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