Climate-driven range changes in Tasmanian intertidal fauna

The south-eastern coast of Australia is recognised as a climate-change hotspot; warming over the past 50 years has exceeded the global average. The marine fauna in the region is responding to this warming with several subtidal species showing a pole-ward range expansion. We provide the first evidence for a similar response in intertidal invertebrates, on the basis of surveys from the eastern coast of Tasmania in 2007-2008 that replicated a set from the 1950s. Of 29 species used in the analysis, 55% were detected further south than in the 1950s. The average minimum movement of the southern (pole-ward) range edges was 116 km (range 20-250 km), representing a rate of ~29 km per decade for a warming rate of 0.228C per decade. Barnacles and gastropods showed the greatest range extensions, with one species absent from Tasmania in the 1950s, the giant rock barnacle, Austromegabalanus nigrescens, now recorded widely along the eastern coast of Tasmania. The distance that the southern (pole-ward) range limit moved south for each species was not related to a qualitative dispersal potential index. Local extinction of some species in north-eastern Tasmania may also occur in the coming decades.