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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13851

Contrasting offspring responses to variation in salinity and temperature among coastal populations: a maladaptive ecological surprise?

Zoran Šargač, Luis Giménez, Steffen Harzsch, Jakob Krieger, Kasper Fjordside, Gabriela Torres*

*Corresponding author:

ABSTRACT: Current understanding of species capacities to respond to climate change is limited by the amount of information available about intraspecific variation in the responses. Therefore, we quantified between- and within- population variation in larval performance (survival, development, and growth to metamorphosis) of the shore crab Carcinus maenas in response to key environmental drivers (temperature, salinity) in two populations from regions with contrasting salinities (32-33PSU: Helgoland-North Sea; 16-20 PSU: Kerteminde-Baltic Sea). We also accounted for the effects of salinity experienced during embryogenesis, which differs between populations. We found contrasting patterns between populations and embryonic salinity conditions. In the Helgoland population, we observed a strong Thermal Mitigation of Low Salinity stress (TMLS) for all performance indicators, when embryos were kept in seawater. The negative effects of low salinity on survival were mitigated at increased temperatures; only at high temperatures, larvae exposed to low salinity were able to sustain high growth rates and reduced developmental time, thereby metamorphosing with comparable levels of carbon and nitrogen to those reared in seawater. By contrast, larvae from the Kerteminde population showed a detrimental effect of low salinity, consistent with a maladaptive response and a weak TMLS. Low salinity experienced during embryogenesis pre-empted the development of TMLS in both populations, and reduced survival for the Kerteminde population, which is a maladaptive response. Our study emphasises the importance of evaluating species responses to variation in temperature and salinity across populations; the existence of maladaptive responses and the importance of the maternal habitat should not be underestimated.