Resource translocation drives δ(13) C fractionation during recovery from disturbance in giant kelp, Macrocystis pyrifera.

Resource allocation and translocation are fundamental physiological functions for autotrophs. The mobilization and use of resources drive population dynamics by regulating growth and recovery of individuals, but also influences ecosystem-level processes such as primary productivity and carbon cycling. This study provides the first observation of translocation-driven gradients of δ(13) C in macroalgae, a critically important phenomenon recognized in vascular plants for decades. A ~10‰ δ(13) C increase in new giant kelp (Macrocystis pyrifera) fronds relative to mature canopy blades was produced after 5 weeks following a biomass removal experiment, more than twice the variation typical for macroalgae. The observed δ(13) C patterns are consistent with tissue enrichment following resource translocation in vascular plants. The analogous source-sink relationships and consistent translocation patterns in Macrocystis and vascular plants suggest that translocation of stored resources is critical for structuring productivity and recovery from disturbance in important, habitat-forming macroalgae such as kelps and fucoids.