Variation in the field metabolic rate of wild living plaice )Pleuronectes platessa) from the North Sea constraining inluences of body size......

The physiological responses of individual organisms drive ecosystem change prompted by
warming sea temperatures. Although critical in predicting population responses to climate change,
the extent to which individuals are able to mitigate temperature effects by modifying behaviour
and metabolic response is unknown. Metabolic scope is the difference between an organism's
standard and maximum metabolic rate. For a given median water temperature, metabolic scope
may be increased behaviourally by reducing total (field) metabolic rate (FMR) by seeking colder
water, by foraging less or by reducing growth. Intra-population metabolic scope may also vary due
to differences in basal metabolic rate. The extent to which populations maintain the capacity to
vary metabolic scope is an unknown but critical concept for predicting species' responses to
climate change. Measuring marine fishes' FMR in natural habitats is a major scientific challenge
currently limiting predictions of fish physiological responses to climate change. Using a new
biogeochemical proxy for FMR based on otolith stable carbon isotope composition, we will explore
the metabolic response of individual fish to decadal temperature change using the Cefas otolith
archive. Focusing initially on plaice, we will for the first time describe spatial and temporal
differences in FMR plasticity across a species thermal range.