Thermal tolerance of the crab Pachygrapsus marmoratus: intraspecific differences at a physiological (CTMax) and molecular level (Hsp70)

Abstract

Temperature is one of the most important variables influencing organisms, especially in the intertidal zone. This work aimed to test physiological and molecular intraspecific differences in thermal tolerance of the crab Pachygrapsus marmoratus (Fabricius, 1787). The comparisons made focused on sex, size, and habitat (estuary and coast) differences. The physiological parameter was upper thermal limit, tested via the critical thermal maximum (CTMax) and the molecular parameter was total heat shock protein 70 (Hsp70 and Hsp70 plus Hsc70) production, quantified via an enzyme-linked imunosorbent assay. Results showed that CTMax values and Hsp70 production are higher in females probably due to different microhabitat use and potentially due to different hormonal regulation in males and females. Among females, non-reproducing ones showed a higher CTMax value, but no differences were found in Hsp70, even though reproducing females showed higher variability in Hsp70 amounts. As reproduction takes up a lot of energy, its allocation for other activities, including stress responses, is lower. Juveniles also showed higher CTMax and Hsp70 expression because they occur in greater shore heights and ageing leads to alterations in protein synthesis. Comparing estuarine and coastal crabs, no differences were found in CTMax but coastal crabs produce more Hsp70 than estuarine crabs because they occur in drier and hotter areas than estuarine ones, which occur in moister environments. This work shows the importance of addressing intraspecific differences in the stress response at different organizational levels. This study shows that these differences are key factors in stress research, climate research, and environmental monitoring.

Heat shock response of the blue crab Portunus pelagicus: thermal stress and acclimation

“…Increasing acclimation temperatures from [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] °C significantly increased the thermal tolerance, which agreed with many previous studies with decapod crustaceans [22,23,27,36,37] . However, the values calculated for the acclimation response ratio.…”

“…Recently, there are several studies on thermotolerance and heat shock in different crab species [22][23][24][25][26][27][28] .…”

Effect of warming rate on the critical thermal maxima of crabs, shrimp and fish

“…Sample sizes were similar to those used by Mora and Ospina (2001) and Madeira et al (2012aMadeira et al ( , 2012bMadeira et al ( , 2012c.…”

“…Crabs needed to be stimulated with a lab tweezer to force them upside down, and if they were unable to get back upright they would have reached the end-point. This criteria is the same followed by Vinagre et al (2013) and Madeira et al (2012aMadeira et al ( , 2012bMadeira et al ( , 2012cMadeira et al ( , 2014b.…”

“…Different patterns of oxidative stress response and heat shock proteins' expression have been detected in crabs, shrimp and fish that occupy different thermal niches in the intertidal-subtidal gradient (Madeira et al, 2012b(Madeira et al, , 2012c. Species that occupy colder and more stable thermal niches present peaks of cellular stress biomarkers at lower temperatures than species that occupy warmer and more variable thermal niches.…”