Composição elementar corporal, desbalanço alimentar e reciclagem de nutrientes em peixes de um riacho costeiro de Mata Atlântica

Abstract

In the present study I evaluated the variation in diet and body elemental composition (C:N:P) of eight fish species that co-occur in two stretches of a stream. In addition, I investigated the differences in demand and excretion of nutrients by two Loricariidae species, one native (Hypostomus punctatus) and the other non-native (Parotocinclus maculicauda). Samplings were performed in Ubatiba River by electrofishing in different months between the years 2010 and 2012. Based on feeding analysis, we observed that species showed variation in diet between sites, with exception of the two species of Characidium. Despite these variations, the present study supported the hypothesis of body stoichiometric homeostasis. The exception was the specie Hoplias malabaricus, which presented variation in body elemental concentration and high food imbalance between sites; differences were most marked in the open area. Analyzing the differences in nutrient demand of Loricariidae we found a higher body concentrations of carbon and nitrogen for the native species and higher phosphorus in the non-native species. This difference was confirmed by a higher consumption of phosphorus by non-native species. The analysis of excretion showed that the native species excrete more nitrogen and phosphorus than non-native. Thus, the results suggest that the non-native species has higher phosphorus demand than the native. Therefore, environments with high concentrations of nutrients, such as the stream studied, may favor the establishment of this species