Background
The authors write that "several studies have provided evidence that thermal stress affects the growth, survival and physiology of tropical and temperate macro-invertebrate species." But they note that "few studies have focused on sub-tidal temperate species and the potential differential thermal tolerances of populations dwelling under contrasting temperature conditions."

What was done
Hoping to help fill this data void by focusing their attention on gorgonians (sessile colonial cnidarians found throughout the oceans of the world), Linares et al. assessed "the role that environmental history plays in the response of the temperate gorgonian Eunicella singularis to thermal stress," comparing populations dwelling in the coldest and warmest areas of the NW Mediterranean Sea.

What was learned
The four researchers report that "E. singularis populations from both areas exhibited a high resistance to thermal stress." However, they found that "populations from warmer areas had an increased tolerance to thermal stress," such that "the upper thermal limits found for cold and warm populations were 28 and 29°C, respectively."

What it means
Linares et al. conclude their study by noting that their results "agree with results for other Mediterranean anthozoans (Rodolfo-Metalpa et al. 2006; Torrents et al., 2008) and tropical corals (Middlebrook et al., 2008), demonstrating thereby that shallow populations (acclimated to warm temperature conditions) have a higher tolerance to thermal stress than deep populations."

References
Middlebrook, R., Hoegh-Guldberg, O. and Leggat, W. 2008. The effect of thermal history on the susceptibility of reef- building corals to thermal stress. Journal of Experimental Biology 211: 1050-1056.

Rodolfo-Metalpa, R., Richard, C., Allemand, D. and Ferrier-Pages, C. 2006. Growth and photosynthesis of two Mediterranean corals, Cladocora caespitosa and Oculina patagonica, under normal and elevated temperatures. Journal of Experimental Biology 2009: 4546-4556.

Torrents, O., Tambutte, E., Caminiti, N. and Garrabou, J. 2008. Upper thermal thresholds of shallow vs. deep populations of the precious Mediterranean red coral Corallium rubrum (L.): assessing the potential effects of warming in the NW Mediterranean. Journal of Experimental Marine Biology and Ecology 357: 7-19.