Latitudinal variability of physiological responses to heat stress of the intertidal limpet Cellana toreuma along the Asian coast

Abstract

Potential future distribution shifts of intertidal invertebrates along the Asian coast in the face of global change remain unclear. Integrative study that comprise environmental temperature monitoring and comparative physiological study of thermal adaptation among different geographical populations of species are important to identify population-related differences in thermal ecology that could affect the persistence of species in their present distribution ranges. In the present study, in situ operative temperatures were recorded continuously for 5 mo from August 2011 to January 2012, and measurements of lethal temperature, cardiac performance and gene expression were carried out in 3 geographical populations of the limpet Cellana toreuma (tropical shore: Sichang Island, Thailand; subtropical shore: Nanding Island, Zhangzhou, China; temperate shore: Dagong Island, Qingdao, China). Compared to limpets on the tropical shore in Sichang Island with high mean temperature (28.28°C) and narrow thermal range (19.13 to 46.56°C), limpets on the subtropical shore in Nanding Island have to cope with a thermal environment characterized by a wider temperature range (6.42 to 44.98°C). The absence of differences in lethal temperature (LT50) of limpets from all the locations indicates that limpets currently suffer from intensive heat stress across their biogeographic range. Although the populations lacked differences in upper thermal limit, variations were noted among populations in transcriptional responses in genes linked to energy metabolism. Limpets on the subtropical shore in Nanding Island live closer to their upper thermal limits and thus will be very sensitive to future temperature increases.