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Journal of Experimental Biology



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Biologging, Body temperature, Bivalve, Inter-individual variation, Tidal rhythm, Valve gaping


Biology | Marine Biology


In complex habitats, environmental variation over small spatial scales can equal or exceed larger-scale gradients. This small-scale variation may allow motile organisms to mitigate stressful conditions by choosing benign microhabitats, whereas sessile organisms may rely on other behaviors to cope with environmental stresses in these variable environments. We developed a monitoring system to track body temperature, valve gaping behavior and posture of individual mussels (Mytilus californianus) in field conditions in the rocky intertidal zone. Neighboring mussels' body temperatures varied by up to 14°C during low tides. Valve gaping during low tide and postural adjustments, which could theoretically lower body temperature, were not commonly observed. Rather, gaping behavior followed a tidal rhythm at a warm, high intertidal site; this rhythm shifted to a circadian period at a low intertidal site and for mussels continuously submerged in a tidepool. However, individuals within a site varied considerably in time spent gaping when submerged. This behavioral variation could be attributed in part to persistent effects of the mussels' developmental environment. Mussels originating from a wave-protected, warm site gaped more widely, and remained open for longer periods during high tide than mussels from a wave-exposed, cool site. Variation in behavior was modulated further by recent wave heights and body temperatures during the preceding low tide. These large ranges in body temperatures and durations of valve closure events – which coincide with anaerobic metabolism – support the conclusion that individuals experience ‘homogeneous’ aggregations such as mussel beds in dramatically different fashion, ultimately contributing to physiological variation among neighbor


This article was originally published in the Journal of Experimental Biology volume 220, issue 22 by the Company of Biologists on November 15, 2017. The article can also be found online at this link.