Using a Food Web Model to Explore the Ecosystem Response to Pacific Lamprey

Resource subsides can have significant ecosystem scale effects to donor communities, particularly when resource conditions are constrained and temporally variable. Streams in the Pacific Northwest, in particular, are seasonally dynamic and nutrient limited. These ecosystems receive much of their energy from terrestrial and marine resource subsidies, which vary seasonally with stream flows, riparian inputs, and anadromous fish runs. To date, most marine subsides studies focused on contributions in autumn from spawning salmonids, a time of deciduous litterfall and declining biological activity that may limit community response to marine nutrients. Currently, no studies have analytically considered the impact of marine subsides from Pacific Lamprey spawning in late spring.  Here, we explore the role of marine subsides from lampreys using a mechanism-based model of periphyton production. Model scenarios assess the relative effect of lamprey and salmon on periphyton across environmental conditions typical of the region. Outcomes from the lamprey-periphyton model expand our understanding of the ecological effects of Pacific Lamprey within their spawning range to inform nutrient enrichment programs throughout the region.