Effects of Fish in River Food Webs

• Published in: Science (American Association for the Advancement of Science) Vol. 250; no. 4982; pp. 811 - 814
• Main Author: Power, Mary E.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 09.11.1990; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Algae; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Cockroaches; Diatoms; Environmental aspects; Fish; Fishes, Fresh-water; Food chains; Food chains (Ecology); Food supply; Food webs; Fresh water ecosystems; Freshwater; Freshwater fishes; Fundamental and applied biological sciences. Psychology; Herbivores; Herbivorous fishes; Pisces; Predators; Rivers; Stream ecology; Synecology; Trophic levels; Young animals; USA, California, Eel R; USA, California; Freshwater environment; Trophic chain; Vertebrata; Primary productivity; Pisces; Trophic relation; Stream
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.250.4982.811

Experimental manipulations of fish in a Northern California river during summer base flow reveal that they have large effects on predators, herbivores, and plants in river food webs. California roach and juvenile steelhead consume predatory insects and fish fry, which feed on algivorous chironomid larvae. In the presence of fish, filamentous green algae are reduced to low, prostrate webs, infested with chironomids. When the absence of large fish releases smaller predators that suppress chironomids, algal biomass is higher, and tall upright algal turfs become covered with diatoms and cyanobacteria. These manipulations provide evidence that the Hairston, Smith, Slobodkin-Fretwell theory of trophic control, which predicts that plants will be alternately limited by resources or herbivores in food webs with odd and even numbers of trophic levels, has application to river communities.