Effect of detritus quality on growth and survival of gizzard shad (Dorosoma cepedianum): potential importance to benthic-pelagic coupling

• Published in: Canadian journal of fisheries and aquatic sciences 2007-12, Vol.64 (12), p.1805-1815
• Main Authors: Kim, Gene W, Wintzer, Alpa P, Menker, Trisha K, Stein, Roy A, Dettmers, John M, Wright, Russell A, DeVries, Dennis R
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal populations; Animal, plant and microbial ecology; Applied ecology; Benthos; Biological and medical sciences; Detritus; Dorosoma cepedianum; Exploitation and management of natural biological resources (hunting, fishing and exploited populations survey, etc.); Fish; Food chains; Food webs; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Lake sediments; Lakes; Marine ecology; Population characteristics; Predation; Predators; Synecology; Trophic levels; Zooplankton
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/f07-143

Gizzard shad (Dorosoma cepedianum) population characteristics vary with lake productivity, competing with and providing prey for sport fishes. Because age-0 gizzard shad (>30 mm total length) are facultative detritivores, they can link benthic energy, carbon, and nutrients to pelagic food webs. To determine how age-0 gizzard shad success varies along a detritus-quality gradient, we completed a 15-day laboratory experiment in which age-0 gizzard shad fed lake sediment and starved gizzard shad both suffered high mortality, whereas fish fed zooplankton grew and survived well. This suggested that detritus alone is insufficient to ensure gizzard shad growth and survival. When sediment quality was high in outdoor mesocosms, density-dependent factors led to rapid growth only at low fish density and high-quality sediments; however, survival generally increased with sediment quality, regardless of gizzard shad density. In four small reservoirs, annual growth of gizzard shad increased with sediment quality. Collectively, our findings suggest that detritus quality ultimately can contribute to regulation of community and ecosystem productivity, mediated by its influence on gizzard shad biomass available for trophic transfer to gape-limited predators (i.e., piscivorous fish). This role of gizzard shad can link higher trophic levels in aquatic food webs to allochthonous detritus subsidies from the surrounding watershed.