We studied the influence of lotic and lentic stretches on zooseston flux in the karstic barrage Plitvice Lakes (Croatia). Three
sampling stretches were selected: 1) a channel with low inclination; 2) water flow through a deep lake (retention), and 3) a channel
with cascades and sharp inclination. At all sampling points of the three stretches, zooseston reached maximum abundance in
September (up to 147.39 ind/m3). Rotifers dominated in both zooseston abundance (58 to 80%) and diversity (66 taxa), followed
by crustaceans (23 taxa), predominantly Cladocera and Copepoda. Kruskal-Wallis test suggest statistically significant differences
between the lentic and both lotic stretches in the biomass net flux of euplanktonic organisms. The net flux of benthic
organism biomass and changes in the biodiversity index were significantly different between the lentic stretch and lotic stretch
with high inclination. Lotic stretches had a greater influence on the increase of abundance and biomass of benthic and semiplanktonic
organisms than on the decrease of euplanktonic organisms. Principal Components Analysis of the species environment
relationship explained 66% of the variance by the two first axes, where axis 1 accounted for 39% and axis 2 accounted for
27% of the variance. Oligochaets, insect larvae, nematodes and total zooseston were associated with component 1, showing that
their biomass was negatively correlated with discharge and dissolved oxygen concentration and positively correlated with temperature.
Other taxa showed a similar correlation with component 1. Biomass of Cladocera, Copepoda, T. birostris, Polyarthra
spp., K. cochlearis and rotifers was associated with component 2, and positively correlated with food resources such as chl-a,
POM and DOM. The inference is that zooseston flux through Plitvice Lakes is a function of the hydrological and physiographical
features of the stretches, as well as food resources from the lakes.