Old before your time: Ancient carbon incorporation in contemporary aquatic foodwebs

Abstract

The current paradigm in trophic dynamic theory is that organisms will gain more energy from fresh, “young” organic materials because they contain the essential elements and chemical characteristics for enhancing growth, unlike more aged and thus conceptually degraded resources. However, a growing body of recent literature is raising exceptions to this resource-age paradigm and highlights that organisms present in diverse aquatic settings in fact incorporate old organic carbon into their biomass. This shift in resource utilization has the potential to alter foodweb stability, structure, and dynamics, but has yet to be integrated into ecological studies and conceptual frameworks. In this review, we first outline a number of recent studies providing direct evidence of the transport and incorporation of old organic carbon in aquatic food webs, and then discuss the ecological implications of this changing view in resource utilization. We ultimately highlight future research avenues that will provide new insights into the response of aquatic foodwebs to the increased mobilization and delivery of old organic carbon to aquatic settings following anthropogenic perturbations and ongoing climatic change.