Plasticity and acquisition of the thermal tolerance (upper thermal limit and heat shock response) in the intertidal species Palaemon elegans

The marine species sensitivity to climate change will depend on the ways by which these species can adapt to thermal increase and heterogeneity. Here, we present evidence that the intertidal shrimp Palaemon elegans acclimates its thermal tolerance, in response to environmental water temperature, through a significant shift of its upper thermal limit with no concomittant acclimation of the heat shock response (hsp70 stress gene expression threshold). This species is less thermotolerant than its congener Palaemonetes varians, and would therefore potentially be more sensitive to an increase in environmental temperature, such as imposed by global warming. In P. elegans life cycle, physiological adjustments like the shift of the thermal limit and the acquisition of a significant HSR, occurred during the metamorphosis from larvae to post-larvae. This suggests that this step is a genetically-programmed milestone in the process of thermal tolerance acquisition.