Dynamics of plankton and fish in a subtropical temporary wetland: Rice fields

摘要

Rice fields are temporary wetlands that harbor many of the same species that breed in natural temporary ponds. These systems have a complex limnology, characterized by rapid physical, chemical, and biological changes. The goal of this study was to evaluate the role of nutrients in the plankton and fish dynamics during a production cycle, based on the auto-ecology of the species related to their adaptations to environmental temporal changes in an irrigated rice field in Southern Brazil. The principal components analysis (PCA) indicated a temporal gradient driven by nutrient availability, grouping sampling periods according to the production cycle. ANOVA indicated temporal differencesin the limnological variablesduring the development of the rice field production cycle. Linear regression showed a positive relationship between chlorophylla, nutrients and biomass ofsmall and medium filter-feeders.In contrast,planktivorous fish biomass wasinversely related to chlorophylla.This study showed both top down and bottom up processes simultaneously regulating the primary production in the rice field wetland along a temporal gradient the rice production cycle.