Radiocarbon in ecology: Insights and perspectives from aquatic and terrestrial studies

Abstract

Abstract Carbon is one of the most abundant elements in the biosphere, and a key element for understanding how consumer and resource relationships affect ecosystem functioning. To trace carbon sources, ecologists predominantly rely on stable carbon ratios but variable 13C baselines and diet‐to‐consumer offsets can lead to ambiguous results. To improve source specificity, ecologists are increasingly turning to radiocarbon (14C). Radiocarbon has a much greater dynamic range and specificity than its stable isotope counterpart because its residence time and carbon sources differ widely among the earth's carbon reservoirs. These source‐specific properties make 14C ideally suited for assessing resource use by animals. In ecological research, 14C has been applied successfully (1) to assess allochthonous and autochthonous contributions to food webs, (2) to distinguish between contributions of recent and old resources to aquatic consumers, and (3) to characterize resource use among terrestrial consumers. While these applications show that 14C is a powerful and complementary tool to stable isotopes, great care should be taken in characterizing relevant 14C baselines in the animals’ environments. Such endeavours have traditionally been expensive owing to the high analytical costs of 14C; however, recent methodological advances are gradually making 14C more affordable and accessible for the average user. Advances in another field, Bayesian mixing modelling make it possible to increase the precision of model estimates by integrating multiple sources of information from 14C and stable isotopes to field observations. Given the recent analytical advances, it is now becoming feasible for many ecologists to embrace 14C as an additional source tracer. We suggest that such efforts will be particularly rewarding when combined with compound‐specific stable isotope analyses because the information that can be drawn from both approaches are highly complementary. Moreover, the possibility of determining 14C of individual compounds can solve long‐standing questions with regard to the origins and fate of particular dietary components. Taken together, these advances will expand the possibilities of accurately determine the origins and fate of carbon through food webs.