Salmon Nutrients and Ecosystems

 

When Pacific salmon spawn and die, their carcasses can fertilize streams and forests with nitrogen and phosphorus. I set up one of the largest field programs on salmon in the world to study ecosystem impacts of salmon, encompassing 50 watersheds in a remote part of the Great Bear Rainforest in Heiltsuk traditional territory on BC’s central coast. We showed, for the first time, that nutrients from salmon alter the community composition of riparian plants in a predictable way according to the ability of species to take up organic or inorganic nitrogen (Hocking & Reynolds, 2011, Science).  These results were derived from over 30,000 records that we collected of percent cover of plant species in the 50 watersheds, and measurements of 6,000 trees. We have also shown  impacts of salmon-derived nutrients on community composition of breeding birds across a wide range of watersheds (Field & Reynolds 2011), as well as strong correlates with scavenging birds in estuaries in the fall, mediated by carnivores (Field & Reynolds 2013). Additional impacts include changes to densities of juvenile coho, which is the first demonstration of effects of nutrients from one species of salmon on another (Nelson & Reynolds 2014).  These and other findings have been used to argue that healthy salmon streams can benefit terrestrial protected areas (Darimont et al. 2010).  We are currently using this information to inform more holistic management of salmon and aquatic habitats.

Our discoveries are in our publications.