Linking Landscapes and Food Webs: Effects of Omnivorous Fish and Watersheds on Reservoir Ecosystems

• Published in: Bioscience Vol. 55; no. 2; pp. 155 - 167
• Main Authors: VANNI, MICHAEL J, AREND, KRISTIN K, BREMIGAN, MARY T, BUNNELL, DAVID B, GARVEY, JAMES E, GONZÁLEZ, MARÍA J, RENWICK, WILLIAM H, SORANNO, PATRICIA A, STEIN, ROY A
• Format: Journal Article
• Language: English
• Published: Circulation, AIBS, 1313 Dolley Madison Blvd., Suite 402, McLean, VA 22101. USA American Institute of Biological Sciences 01-02-2005; University of California Press; Oxford University Press
• Subjects: Adults; Agricultural industry software; Agriculture; Detritus; Ecology; Ecosystems; Fish; Food chains; food web; Food webs; Land; Land use; Landscape ecology; Nutrients; omnivores; OVERVIEW ARTICLES; Phytoplankton; reservoir; Reservoirs; Soil Science; Water column; Water pollution; watershed; Watersheds; Zooplankton; watershed; reservoir; landscape ecology; food web; detritus
• ISSN: 0006-3568; 1525-3244
• DOI: 10.1641/0006-3568(2005)055[0155:LLAFWE]2.0.CO;2

Ecologists increasingly recognize the need to understand how landscapes and food webs interact. Reservoir ecosystems are heavily subsidized by nutrients and detritus from surrounding watersheds, and often contain abundant populations of gizzard shad, an omnivorous fish that consumes plankton and detritus. Gizzard shad link terrestrial landscapes and pelagic reservoir food webs by consuming detritus, translocating nutrients from sediment detritus to the water column, and consuming zooplankton. The abundance of gizzard shad increases with watershed agriculturalization, most likely through a variety of mechanisms operating on larval and adult life stages. Gizzard shad have myriad effects on reservoirs, including impacts on nutrients, phytoplankton, zooplankton, and fish, and many of their effects vary with ecosystem productivity (i.e., watershed land use). Interactive feedbacks among watersheds, gizzard shad populations, and reservoir food webs operate to maintain dominance of gizzard shad in highly productive systems. Thus, effective stewardship of reservoir ecosystems must incorporate both watershed and food-web perspectives.