PloS ONE 6, e29657 (2011)

Credit: © JOÃO CANNING-CLODE

The poleward expansion of plants and animals is a widely observed response to climate change. However, despite a tendency towards warmer and milder conditions, climate change is not expected to eliminate periodic cold events, yet their effect on species range expansion is rarely considered.

João Canning-Clode, from the University of the Azores, and co-authors investigated the effect of cold events on the green porcelain crab, which is one of the Caribbean 'invaders' that are now found on the southern and mid-Atlantic coasts of the United States — a phenomenon known as 'Caribbean creep'.

They found that the crabs could not tolerate exposure to temperatures that mimic unusual and severe cold spells on the southern and mid-Atlantic US coasts. As a result the authors suggest that occasional cold winters may be a critical reset mechanism that will limit the range expansion of other 'Caribbean creep' species.