Numerous species get smaller and smaller as a result

Sep 23, 2011 17:21 GMT  ·  By
Increasing temperatures are forcing cold-blooded animals to decrease in size
   Increasing temperatures are forcing cold-blooded animals to decrease in size

For quite some time now, investigators looking into the effects of global warming on ecosystems have been warning that climate change is causing species to diminish in size. A new investigation, conducted on tiny marine creature known as copepods, provides the first insights into how this happens.

Decades ago, the influence of global warming was minimal, but now the phenomenon is being exacerbated by our unwillingness to do anything about it. As a result, the severity of its effect has been increasingly abruptly, rather than steadily.

In addition to melting glaciers and ice caps, triggering more droughts and floods, threatening low-lying coastal areas and acidifying the world's oceans, the global phenomenon is apparently also causing an unwanted evolutionary response in numerous species, forcing them to decrease in size.

Studies have already demonstrated beyond a shadow of a doubt that cold-blooded species are affected by this change. The more heat there are subjected to in their environments, the more likely they are to drop in body size. The other alternative is to change their habitats.

However, very few species prefer this option, since they evolved for millions of years to fit a certain niche in a very specific ecosystem. Already, they are under tremendous pressure to fight invasive species, which are driven to new territories by changing temperatures.

In the recent study, Queen Mary, University of London (QMUL) expert Andrew Hirst wanted to discover why a 1-degree Celsius increase in temperature leads to a 2.5 percent decrease in body size.

The first thing the expert did was put together a comprehensive database that showed how 15 different species of copepod grew under varied environmental conditions. One of the most important things the team discovered was that higher temperatures forced the organisms to mature faster.

According to Hirst, this may have something to do with the fact that reactions and processes occurring in their tiny bodies – their metabolisms – are accelerated by warmth. Even though they grew in size rapidly, the copepods reached maturity faster, therefore stopped growing faster, New Scientist reports.

“If you start changing the copepods, you could cause all sorts of unpredictable knock-on effects in the ecosystem,” explains Imperial College London (ICL) expert Tim Coulson, who was not a part of the new research.