Salmon in the Trees: an Assessment of Dendrochemical Techniques for Detecting Marine Derived Nutrients in Tree Rings

Anadromous Pacific salmon spend the majority of their lives feeding and growing at sea.  The stable isotope ¹⁵N is naturally more abundant in marine environments than in terrestrial or freshwater environments, and returning salmon are enriched with ¹⁵N relative to ¹⁴N, the more common N isotope.  As a consequence, salmon returning to spawn in their natal streams are enriched with ¹⁵N and contribute a traceable isotopic signature to surrounding freshwater and riparian systems upon death.  This isotopic signaturemay be evident in annual growth rings of riparian trees proportional to the numbers of salmon spawning in the system.  This study tests the viability of dendrochemical analysis as a technique for detecting past contributions of salmon-borne MDN to riparian trees potentially allowing for the reconstruction of historical trends in salmon distribution and abundance while enhancing our understanding of processes governing nutrient cycling in coastal ecosystems.