Meeting Abstract

70.6  Saturday, Jan. 5  The effect of exposure to multiple environmental challenges on multiple physiological responses: an inter-individual approach CALOSI, P*; TURNER, LM; HAWKINS, M; NIGHTINGALE, G; BERTOLINI, C; TRUEBANO-GARCIA, M; FORD, A; SPICER, JI; Plymouth University; Plymouth University; Plymouth University; Plymouth University; Plymouth University; Plymouth University; University of Portsmouth; Plymouth University piero.calosi@plymouth.ac.uk

Continuing increase in atmospheric CO₂ anthropogenic emissions will lead to an increase in ocean-surface temperature of 3-5&degC, and a decrease in pH of 0.3-0.4 units by 2100. Whilst marine intertidal organisms already experience periodical environmental fluctuations that exceed these values, and are believed to be adapted to these conditions, actual data on how they respond to chronic exposure is limited. Moreover, investigations to date have typically employed independent sample analysis (ITSA), which is a powerful tool for the detection of significant alterations of biological responses. However, ITSA does not take into account inter-individual variation and relationships between traits. Here, we investigated individuals’ metabolic rate (MR), gill Na⁺ / K⁺-ATPase activity and upper thermal tolerance (UTT) in adults of the amphipod Gammarus marinus exposed for 15 days to combined elevated temperature and CO₂. Briefly, ITSA detected significant up-regulation in gill Na⁺/K⁺-ATPase activity in individuals exposed to elevated temperature and CO2 and a significant decrease in upper thermal tolerance (UTT) in the high-CO₂ treatment. ITSA revealed that UTT responses are largely but weakly MR-dependent, and that sUTT response to CO₂ and temperature exposure depended also on individuals’ MR. We will discuss the advantages and disadvantages of integrating ITSA and ILSA when interpreting organisms’ biological responses within the context of global change.