Physical, chemical and biological features of three oxbow lakes of Mogi- Guaçu River í SP and assessment of its role as fish nursery areas of reophilic species

Abstract

This study presents the results of monthly collections (June/1997 to June/1998) of some physical and chemical water variables, phytoplankton, zooplankton and fish that were obtained in three oxbow lakes of Mogi-Guaçu River. Two lakes are located within a preserved region (Experimental Station of Mogi-Guaçu, SP) and the third one, in an agricultural area in Pirassununga District (SP). The "curimbatá" (Prochilodus lineatus) was the most abundant rheophilic fish species in all lakes. No young individuals of this and other fish species were found during the study. The zooplankton community was composed of 87 taxa; rotifers showed the highest species richness (54 taxa), followed by cladocerans (26 taxa) and cyclopoid copepods (6 taxa). For the phytoplankton, 47 taxa were registered, with Euglenophyceae presenting the highest species richness (53.1%), followed by Chlorophyceae (21.2%). A Principal Component Analysis performed on the physical and chemical water parameters indicated that Rio das Pedras lake differed from Barrinha and Catingueiro lakes, since it is more eutrophic. The structure and the importance of the planktonic community as the food basis was discussed, and the role of the three lakes as fish nursery areas assessed.