Linking Species to Ecosystems: Effects of Spawning Salmon on Aquatic Ecosystem Function

Abstract

Over 20 years of research has highlighted how Pacific salmon (Oncorhynchus spp.) returning from the ocean to natal lakes, rivers, and streams can have profound impacts on inland coastal ecosystems, and salmon are now an archetypal example of biological resource subsidies by migratory animals. A myriad of consumers from bears to insects rely on the annual return of salmon for food. The use of stable isotopes to track nitrogen from salmon tissues has also suggested that marine-derived nutrients delivered by salmon are important for sustaining the long-term productivity of both aquatic and terrestrial ecosystems in salmon areas. I will consider the widely-held notion that salmon provide critical limiting nutrients that stimulate productivity of recipient ecosystems, and present new research which suggests a more nuanced view of this well known example of spatial resource subsidies is appropriate. Along the way, I will also present new analytical and statistical methods for quantifying aquatic ecosystem metabolism in streams.