Jg. Qin et Da. Culver, EFFECT OF YOUNG-OF-THE-YEAR WALLEYE (PERCIDAE, STIZOSTEDION-VITREUM) ON PLANKTON DYNAMICS AND WATER-QUALITY IN PONDS, Hydrobiologia, 297(3), 1995, pp. 217-227
To understand the impact of young-of-the-year (YOY) fish on food web d
ynamics and water quality, we stocked larval walleye (9 mm TL) (Stizos
tedion vitreum) in six experimental ponds using two fish densities (10
and 50 fish m(-3)) with three replicates. At high fish density, the a
verage abundances of cladocerans and copepods and the Secchi depth wer
e lower whereas abundances of rotifers and algae, gross primary produc
tivity (GPP), pH and total phosphorus concentration were higher than a
t low fish density. Fish impact on bacterial abundance, dissolved oxyg
en, nitrogen and phosphorus concentrations, however, was not significa
nt. The within treatment measurements of all variables except GPP were
significantly different over time. Our results indicate that YOY wall
eye predation at high density can affect plankton community by reducin
g large zooplankton biomass and water clarity, and increasing phytopla
nkton abundance. The impact of YOY piscivorous fish on plankton should
be considered when biomanipulation is applied for improvement of wate
r quality.