Honey, we shrank the copepods
29 September 2011
Honey, we shrank the copepods. These tiny marine animals offer a clue to why a warming climate makes animals smaller.
It is well established that cold-blooded species get smaller as the climate heats up, says Dr Andrew Hirst from School of Biological and Chemical Sciences at Queen Mary, University of London. Experiments show that, on average, 1°C of warming reduces their adult body mass by 2.5 per cent. The mystery is why.
To find out, Hirst pulled together data on 15 species of copepod that swim in the open sea, focusing on how they grew at different temperatures. As temperatures rose, the copepods got heavier faster, probably, Hirst thinks, because physiological reactions accelerate at warmer temperatures. However, they also matured faster, so their rapid growth ground to a halt at a young age. The overall effect is that the warmer copepods end up smaller.
This story has been reported in New Scientist.