Predição e mecanismos reguladores da biomassa de peixes em reservatórios do Paraná e bacias limítrofes

Abstract

A set of different mechanisms and factors may regulate secondary production of ecosystems. Abiotic variables, primary production and zooplankton data were used to built a model to predict fish biomass from 29 reservoirs of Paraná State and limitrophe watershed. A multiple regression model with two variables (chlorophylla and zooplankton) was found to predict fish biomass (R² = 0.59). Chlorophyll-a (and index of primary production) was positively correlated (positive slope), suggesting its potential as regulator of fish biomass. But, zooplankton was negatively correlated (negative slope) to fish biomass. However, zooplankton was positively correlated to chloropyll-a, denoting a possible grazing effect of zooplankton on phytoplankton, decreasing detritus production, and consequently, fish biomass. Therefore, an intermediary mechanism can be acting on the trophic chain, regulating fish biomass in these reservoirs.