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MEPS prepress abstract   -  DOI:

Thermal tolerance differs between co-occurring congener beetle species in marine supratidal rockpools

J. M. Mirón-Gatón*, M. Botella-Cruz, A. J. García-Meseguer, A. Millán, J. Velasco

*Corresponding author:

ABSTRACT: In the context of global change, it is important to know species’ physiological limits and behavioural responses to environmental changes, especially for those living in extreme environments like supratidal rockpools. Our main study objective was to determine the thermal tolerance of three beetle species (Ochthebius quadricollis, O. subinteger, O. lejolisii) co-occurring on the western Mediterranean coast through physiological and behavioural thermoregulatory responses to predict their sensitivity to climate change. To this end we: (1) compared the heat coma (HC) among species and populations; (2) in O. quadricollis and O. lejolisii explored the effect of salinity on HC in adults and larvae; and (3) determined the temperature thresholds for avoidance responses (water emersion and flight) of adult stages against heat and salinity stressors. We found significant interspecific and interpopulation differences in HC. O. quadricollis larvae and adults were the most heat-tolerant, showing similar HC values under different salinity conditions. In O. lejolisii, high salinity (90 g l-1) conferred greater thermal tolerance in larvae but lower tolerance in adults. The temperature thresholds for avoidance responses were generally lower than 40ºC, but interspecific variation followed their obtained HC patterns. In both these species, salinity affected the sublethal temperature thresholds on water emersion. An additive effect of temperature and salinity was observed for the frequency of emergence and flight in both species. Our results provide relevant information for estimating thermal-safety margins and developing mechanistic predictive models for these species’ survival when faced with current and future climate change scenarios.