2001 - 2001 Centre for Environment, Fisheries & Aquaculture Science (Cefas) Environmental correlates of large-scale spatial variation in the Delta13C of marine animals

Carbon stable isotopes can be used to trace the sources of energy supporting food chains and to estimate the contribution of different sources to a consumer's diet. However, the δ13C signature of a consumer is not sufficient to infer source without an appropriate isotopic baseline, because there is no way to determine if differences in consumer δ13C reflect source changes or baseline variation. Describing isotopic baselines is a considerable challenge when applying stable isotope techniques at large spatial scales and/or to interconnected food chains in open marine environments. One approach is to use filter-feeding consumers to integrate the high frequency and small-scale variation in the isotopic signature of phytoplankton and provide a surrogate baseline, but it can be difficult to sample a single consumer species at large spatial scales owing to rarity and/or discontinuous distribution. Here, we use the isotopic signature of a widely distributed filter-feeder the queen scallop ( *Aequipecten opercularis* ) in the north-eastern Atlantic to develop a model linking base δ13C to environmental variables. Data includes catch data, isotope analysis data, environmental data and associated positional data.