Planktivores and Plankton Dynamics: Effects of Fish Biomass and Planktivore Type
Keywords:fish biomass effects
planktivore type effects
filter-feeding gizzard shad
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Citation:Lazzaro, Xavier; Drenner, Ray W.; Stein, Roy A.; Smith, J. Durward "Planktivores and Plankton Dynamics: Effects of Fish Biomass and Planktivore Type," Canadian Journal of Fisheries and Aquatic Sciences, v. 49, no. 7, 1992, pp. 1466-1473.
We quantified the effects of planktivore biomass and planktivore type in an experimental mesocosm study of factorial design in which five levels of fish biomass (0-75 g/m3) were cross-classified with two planktivore types: filter-feeding gizzard shad (Dorosoma cepedianum) and visual-feeding bluegill (Lepomis macrochirus). As fish biomass increased, cladocerans, cyclopoids, particulate phosphorus (PP) >200 µm, and chironomids declined; conversely, rotifers, primary productivity, chlorophyll a, turbidity, unicellular flagellates, colonial and unicellular green algae, pennate diatoms, total phosphorus, and 20-200 and 12-20 µm PP were enhanced. In the presence of gizzard shad, as compared with bluegill, cyclopoids, turbidity, unicellular green algae, pennate diatoms, >200 µm PP, and chironomid tubes were higher whereas colonial green algae and <0.2 µm PP were lower. Fish biomass operated independently of planktivore type for most variables, except copepods, colonial green algae, turbidity, and 20-200 µm PP. Although gizzard shad and bluegill have different trophic cascade pathways, fish biomass was more important than planktivore type as a regulator of plankton communities and water quality.
Funding for this project was provided by ORSTOM action 2CA301 to X.L., NSF grant BSR-8906653 to R.W.D. and J.D.S., NSF grant BSR-9107173 to R.A.S., and the OSU Aquatic Ecology Laboratory.