Edition 5, June 2010
East Australian Current Bolsters Tasmania's Invading Sea Urchin Numbers
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June 18th, 2010
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| East Australian Current. Image source |
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Native sea urchin (Centrostephanus rodgersii) populations invading Tasmanian waters are being continuously replenished and spread by the southward expansion of the warming East Australian Current under climate change.
Unlike non-native species, which often go through a genetic bottleneck when they reach somewhere new, genetic and population analysis by Sam Banks and colleagues shows the urchins have high connectivity between the source and new populations.
This is because the larvae keep floating south from the mainland on journeys that can last up to four months.
Tasmania was apparently too cold for the urchin before the 1960s. But the seas there have been warming at more than double the global average from a strengthening of the warm southward-flowing East Australian Current.
According to the researchers, opportunistic species like the urchin that respond early to climate change “may be considered invasive, and negatively impact on ‘naive’ ecosystems”.
When the urchin colonises rocky reefs, it forms barrens devoid of algae and associated fauna. Because Tasmanian rocky reef communities do not have any suitable habitat further south, “the ecological impacts of invasion by warmer water species such as C. rodgersii may constitute a major threat to the persistence of such ecosystems”.
References
Banks SC, Ling SD, Johnson CR, Piggott MP, Williamson JE and Beheregaray LB. 2010. Genetic structure of a recent climate change-driven range extension. Molecular Ecology 19(10): 2011-2024.