![]() Įvery year in the Pacific Northwest anadromous salmon ( Oncorhynchus spp.) transport marine-derived nutrients from the North Pacific Ocean into coastal ecosystems. It is generally recognized that downstream transport of terrestrial nutrients into marine estuaries produces one of the world's most productive habitats, but recent investigations suggest that the reverse flow, from marine to terrestrial habitats, may also be exceptionally important in structuring highly diverse coastal ecosystems. Nutrient cycling between geographically distinctive ecosystems can produce zones of major productivity and biodiversity. Salmon nutrient subsidies to terrestrial habitats may result in shifts in invertebrate community structure, with subsequent implications for higher vertebrate consumers, particularly the passerines. ConclusionsĮnrichment of δ 15N in the invertebrate community below the falls in conjunction with the absence of δ 13C enrichment suggests that enrichment in δ 15N occurs primarily through salmon-derived nitrogen subsidies to litter, soil and vegetation N pools rather than from direct consumption of salmon tissue or salmon tissue consumers. From 19.4 to 71.5% of invertebrate total nitrogen was originally derived from salmon depending on taxa, watershed, and degree of fractionation from the source. Invertebrates varied in δ 13C but did not always vary predictably with trophic level or habitat. We observed increasing δ 15N levels in our invertebrate groups with increasing consumption of dietary protein. Invertebrates varied predictably in δ 15N with enrichment of 3–8‰ below the falls compared with above the falls in all trophic groups on both watersheds. We use a dual isotope approach of δ 15N and δ 13C to test for the contribution of salmon nutrients to multiple trophic levels of litter-based terrestrial invertebrates below and above waterfalls that act as a barrier to salmon migration on two watersheds in coastal British Columbia. On the Pacific coast of North America, anadromous salmon ( Oncorhynchus spp.) constitute a dominant nutrient subsidy to aquatic habitats and riparian vegetation, although the contribution to terrestrial habitats is not well established. ![]() Bi-directional flow of nutrients between marine and terrestrial ecosystems can provide essential resources that structure communities in transitional habitats. ![]()
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