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FISH INVASION RESTRUCTURES STREAM AND FOREST FOOD WEBS BY INTERRUPTING RECIPROCAL PREY SUBSIDIES

FISH INVASION RESTRUCTURES STREAM AND FOREST FOOD WEBS BY INTERRUPTING RECIPROCAL PREY SUBSIDIES Habitat alteration and biotic invasions are the two leading causes of global environmental change and biodiversity loss. Recent innovative experiments have shown that habitat disturbance can have drastic effects that cascade to adjacent ecosystems by altering the flow of resource subsidies from donor systems. Likewise, exotic species invasions could alter subsidies and affect distant food webs, but very few studies have tested this experimentally. Here we report evidence from a large-scale field experiment in northern Japan that invasion of nonnative rainbow trout ( Oncorhynchus mykiss ) interrupted reciprocal flows of invertebrate prey that drove stream and adjacent riparian forest food webs. Rainbow trout usurped terrestrial prey that fell into the stream, causing native Dolly Varden charr ( Salvelinus malma ) to shift their foraging to insects that graze algae from the stream bottom. This indirectly increased algal biomass, but also decreased biomass of adult aquatic insects emerging from the stream to the forest. In turn, this led to a 65%% reduction in the density of riparian-specialist spiders in the forest. Thus, species invasions can interrupt flows of resources between interconnected ecosystems and have effects that propagate across their boundaries, effects that may be difficult to anticipate without in-depth understanding of food web relationships. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ecology Ecological Society of America

FISH INVASION RESTRUCTURES STREAM AND FOREST FOOD WEBS BY INTERRUPTING RECIPROCAL PREY SUBSIDIES

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References (35)

Publisher
Ecological Society of America
Copyright
Copyright © 2004 by the Ecological Society of America
Subject
Regular Article
ISSN
0012-9658
DOI
10.1890/04-138
Publisher site
See Article on Publisher Site

Abstract

Habitat alteration and biotic invasions are the two leading causes of global environmental change and biodiversity loss. Recent innovative experiments have shown that habitat disturbance can have drastic effects that cascade to adjacent ecosystems by altering the flow of resource subsidies from donor systems. Likewise, exotic species invasions could alter subsidies and affect distant food webs, but very few studies have tested this experimentally. Here we report evidence from a large-scale field experiment in northern Japan that invasion of nonnative rainbow trout ( Oncorhynchus mykiss ) interrupted reciprocal flows of invertebrate prey that drove stream and adjacent riparian forest food webs. Rainbow trout usurped terrestrial prey that fell into the stream, causing native Dolly Varden charr ( Salvelinus malma ) to shift their foraging to insects that graze algae from the stream bottom. This indirectly increased algal biomass, but also decreased biomass of adult aquatic insects emerging from the stream to the forest. In turn, this led to a 65%% reduction in the density of riparian-specialist spiders in the forest. Thus, species invasions can interrupt flows of resources between interconnected ecosystems and have effects that propagate across their boundaries, effects that may be difficult to anticipate without in-depth understanding of food web relationships.

Journal

Ecology – Ecological Society of America

Published: Oct 1, 2004

Keywords: food webs ; Hokkaido, Japan ; invasion ecology ; large-scale field experiment ; Oncorhynchus mykiss ; resource subsidies ; riparian ecology ; Salvelinus malma ; stream ecology

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