Abstract
Different combinations of behavioural and physiological responses may play a crucial role in the ecological success of species, notably in the context of biological invasions. The invasive mussel Xenostrobus securis has successfully colonised the inner part of the Galician Rias Baixas (NW Spain), where it co-occurs with the commercially-important mussel Mytilus galloprovincialis. This study investigated the effect of a heatwave on the physiological and behavioural responses in monospecific or mixed aggregations of these species. In a mesocosm experiment, mussels were exposed to simulated tidal cycles and similar temperature conditions to those experienced in the field during a heat-wave that occurred in the summer of 2013, when field robo-mussels registered temperatures up to 44.5°C at low tide. The overall responses to stress differed markedly between the two species. In monospecific aggregations M. galloprovincialis was more vulnerable than X. securis to heat exposure during emersion. However, in mixed aggregations, the presence of the invader was associated with lower mortality in M. galloprovincialis. The greater sensitivity of M. galloprovincialis to heat exposure was reflected in a higher mortality level, greater induction of Hsp70 protein and higher rates of respiration and gaping activity, which were accompanied by a lower heart rate (bradycardia). The findings show that the invader enhanced the physiological performance of M. galloprovincialis, highlighting the importance of species interactions in regulating responses to environmental stress. Understanding the complex interactions between ecological factors and physiological and behavioural responses of closely-related species is essential for predicting the impacts of invasions in the context of future climate change.
Highlights
Climate change is likely to alter community composition in many terrestrial and marine systems through range shifts, differential responses to thermal stress, and changes in interactions between species [1,2]
Organisms inhabiting the rocky intertidal zone are especially vulnerable to climate change because they are exposed to both marine and terrestrial conditions, and some species are sometimes exposed to conditions close to their physiological limits for stress [3]
Mortality was higher in individuals exposed to heatwave conditions
Summary
Climate change is likely to alter community composition in many terrestrial and marine systems through range shifts, differential responses to thermal stress, and changes in interactions between species [1,2]. Organisms inhabiting the rocky intertidal zone are especially vulnerable to climate change because they are exposed to both marine and terrestrial conditions, and some species are sometimes exposed to conditions close to their physiological limits for stress [3]. In this zone, abiotic conditions may shift even more dramatically over scales of just a few metres. Various studies have documented the consequences of the intertidal stress gradient on invertebrates (e.g. [14,19,22,23,24]), the sub-lethal effects of stress on the ecology and physiology of these organisms have been less well studied
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