Climate change driven seaweed range shifts

There is a really neat new paper on species range shifts in response to global warming in Current Biology (Wernberg et al 2011).  The authors used an exquisite online database of >20,000 herbarium records of macroalgae collected in Australia since the 1940s to assess changes in the northern range limits of seaweed. On both Australia’s west and east coasts, a far greater proportion of species experienced poleward range shifts – what you’d expect if species were responding to a warming environment.  Moving enables populations to stay in an optimum thermal environment when climate is changing.  Such movement generally isn’t planned or conscious, but rather the result of differential survival and population growth rates across a latitudinal thermal gradient.

The records the authors worked with can be seen here. Each record includes a pressed and dried specimen and collection notes about the location, dates, etc. The study highlights the value of such collections as natural history and ecological repositories that become more valuable the older they are.  Below is an example of Claudea elegans, a red alga collected in western Oz.

One of the neat – if depressing – aspects of the paper is that the authors estimated how many species ranges would be “shifted” right off the Australian continent if regional warming continued at it’s present rate through 2070: 100-350 species or as much as 25% of seaweed species in the region.  And remember, south of Australia is, well nothing until you get to Antarctica. These species would be migrating to oblivion, not to the next island down the line.

Ironically, Anthony Watts covered this study long before we did in a post cleverly titled Kelp! Kelp! It’s warming! It seems Anthony, like many coral reef scientists, don’t care for seaweed or take their conservation seriously!  The comments were – as is usually the case on WUWT – telling and entertaining;

Rob Starkey says:  The article seems meaningless. If there was data that overall plant growth was being harmed it would be meaningful, but who cares what individual types of plants do well?

Martin Brumby says: Seaweed. More scuba diving “scientists” on the taxpayer’s dollar.

yeah, so, what’s your point Martin?!

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