Meeting Abstract
21.2 Saturday, Jan. 4 13:45 Physiological responses of two intertidal barnacles (Tetraclita japonica and Megabalanus volcano) to heat stress WONG, K.K.W.*; TSANG, L.M.; HUI, J.H.L.; CHAN, B.K.K.; CHU, K.H.; School of Life Sciences, The Chinese University of Hong Kong; Institute of Marine Biology, National Taiwan Ocean University; School of Life Sciences, The Chinese University of Hong Kong; Biodiversity Center, Academia Sinica, Taiwan; School of Life Sciences, The Chinese University of Hong Kong wkwkaren83@yahoo.com.hk
Inhabitants of rocky intertidal zone are subjected to periodic tidal emersions and enormous thermal stress during daytime low tides. Tetraclita japonica and Megabalanus volcano are two common intertidal barnacles found in Hong Kong, with T. japonica occupying mid to high intertidal zone and M. volcano occupying low intertidal to subtidal zone. In this study, body temperature, hemolymph osmolality, and responses to thermal challenge were compared between the two species. 1) Measurement of body temperature in the field revealed contrasting thermal profiles. T. japonica at the upper shore experienced greater thermal stress than T. japonica and M. volcano at low shore. 2) Aerial exposure of barnacles was found to be associated with the increase in hemolymph osmolality. M. volcano with lower body temperature showed a more significant increase than T. japonica at a similar shore level. 3) When the two species were thermally challenged at 40 °C rock temperature for 5 h, T. japonica entered coma state much earlier than M. volcano and 94% T. japonica lose irritability in comparison to only 36% M. volcano did. However, all individuals of T. japonica resumed activity when immersed into water, and M. volcano in coma did not show any activities and died within 24 h. Given these results, we suggested the loss of irritability during the early stage of acute heat stress could be a strategy for T. japonica to cope with thermal stress. Transcriptomic analysis is now being carried out to dissect the differential gene expression of the two species upon heat stress.
