Uptake of salmon‐derived nitrogen by mosses and liverworts in coastal British Columbia

Abstract

Throughout forested watersheds bordering the North Pacific, anadromous salmon (Oncorhynchus spp. ) are transferred into coastal forests by numerous predators and scavengers with remnants providing an important nutrient subsidy to riparian zones. The contribution of these nutrients to mosses and liverworts, which are the dominant ground cover of coastal forests, has not been investigated. We examine here d 15 N isotope signatures and foliar percent N of eight moss and liverwort species, as well as moss and liverwort community structure, in multiple habitat blocks that vary in access to salmon nutrients from two watersheds on the central coast of British Columbia. For the most common moss Rhytidiadelphus loreus, we also examine d 15 N values and foliar percent N among salmon carcass micro-sites and along wildlife trails. Overall, d 15 N signatures ranged from 2 to 7 higher below the falls near the salmon stream than above the small falls that are impassable to salmon, or at the adjacent control watershed that had no salmon. Among micro-sites, d15 N and %N values were highest near bony carcass remnants from transfer during previous years and high adjacent to wildlife trails indicating spatial heterogeneity in the salmon nutrient pools of these forests. Species richness and prevalence of nitrogen-rich soil indicators were also highest in forests adjacent to the salmon stream. These data suggest an important contribution of salmon-derived nutrients to the non-vascular plants of the riparian zone of old-growth forests throughout the Pacific Rim.

Chinook salmon invade southern South America

“…Although ChS cease feeding after entering freshwater (Healey 1991; this study), they can impact aquatic, riverine, and terrestrial ecosystems through the nutrients released on their death (Soto and Campos 1995;Soto et al 2007) as well as parasites from the ocean (the macro-parasite fauna found in our field survey is described in Bravo 2005). Input of marine-derived nutrients may result in increased basal food web production (Zhang et al 2003;Wilkinson et al 2005), and cascade to upper trophic levels (Bilby et al 1998). These are only a few simple examples of how ChS invasion may impact local ecosystems.…”

Nitrogen uptake by plants subsidized by Pacific salmon carcasses: a hierarchical experiment

“…Along with other pathways of salmon nutrient entry into terrestrial food webs, such as flooding and hyporheic water flow, salmon subsidies may ultimately affect riparian plant diversity (Wilkinson et al 2005;Hocking and Reynolds 2011).…”

The ecology of terrestrial invertebrates on Pacific salmon carcasses

“…For example, nutrient release from carcasses can influence plant growth and community structure (Wilkinson et al 2005;Drake and Naiman 2007), while diet shifts to salmon in consumers can alter predator-prey dynamics (Darimont et al 2008) and rates of detrital processing (Zhang et al 2003). Terrestrial insect groups such as blowflies (Calliphoridae) and burying beetles (Silphidae) also increase processes of salmon decomposition and nutrient distribution in forest riparian zones (Jauquet et al 2003;Meehan et al 2005;.…”