Reference
Byrne, M., Selvakumaraswamy, P., Ho, M.A., Woolsey, E. and Nguyen, H.D. 2011. Sea urchin development in a global change hotspot, potential for southerly migration of thermotolerant propagules. Deep-Sea Research II 58: 712-719.
What was done
To address questions relating to potential future vulnerabilities of the sea urchin Heliocidaris erythrogramma along the southeast coast of Australia, where sea surface temperatures (SSTs) have risen by 2.3°C over the last 60 years, the authors studied the thermotolerance of the urchin's planktonic life phase in experimental treatments ranging from 18 to 26°C, with the latter value representing a 3 to 4°C increase above recent ambient SSTs.
What was learned
Byrne et al. determined that "development success across all stages (gastrula, 24 h; larva, 72 h; juvenile, 120 h) decreased with increasing temperature," and they forthrightly acknowledge that "significant deleterious effects were evident at +3 to 4°C." However -- and this is a very big 'however' -- they report that "larvae that developed through the early bottleneck of normal development at 26°C metamorphosed successfully," and they add that there was a 25% decrease in planktonic larval duration (PLD) of the larvae in the highest of the temperature treatments. In addition, they found that in parallel studies with progeny derived from the northern and southern parts of the coastline they studied, "northern embryos had significantly higher thermotolerance."
What it means
In discussing their findings, the five researchers say that ocean warming may be advantageous to H. erythrogramma larvae "through early settlement and reduction of the vulnerable planktonic period." They also state that the higher thermotolerance of the species' northern embryos "provides the possibility that H. erythrogramma populations might keep up with a warming world through poleward migration of thermotolerant propagules, facilitated by the strong southward flow of the East Australian Current." And thus they conclude that "due to its extensive latitudinal distribution, its potential developmental thermotolerance and independence of its lecithotrophic larvae from exogenous food and the need to make a functional skeleton, H. erythrogramma may be particularly robust to ocean change."