Biologia de populações de peixes do Riachos da Vila de Itatinga, Bertioga, São Paulo

Abstract

The ichthyofauna is closely related to the structural characteristics of the environments in which they live, as well as are observed functional relations between substrate and marginal vegetation and the fish species, as those are the places where many species find food, also having ideal conditions for spawning and survival of the offspring, this study aims to verify if there is a relationship between the welfare of the species and the environment, based on the biology evaluation of nine fish species from Villa de Itatinga streams, in Bertioga/SP. The samplings occurred monthly, over a year, in eleven streams. The collection of limnological variables were obtained monthly with a multi-parameter water quality checker and also from sampled water analyzes. In the laboratory, the specimens were identified at the species level and the following dimensions were taken: total and standard length, total weight and after dissection when the stomachs and gonads were removed and weighed, the external repletion degree of the stomach, sex and stage of gonadal maturation were obtained. A total of nine most representative species were studied. The species that presented normality in the frequency distributions were predominant, and only females of Mimagoniates microlepis and males of Characidium lanei, Phalloceros harpagos and Kronichthys heylandi did not show normality. All species presented sex ratio different than the expected of 1:1. Female specimens of the species Deuterodon iguape, Characidium japuhybense, C. lanei, P. harpagos and Acentronichthys leptos were larger than males, while the opposite occurred in the species Hollandichthys multifasciatus, M. microlepis, K. heylandi and Scleromystax barbatus. Only C. lanei and A. leptos showed no difference between dry and rainy periods and only K. heylandi showed difference between sexes. Hollandichthys multifasciatus, C. japuhybense, females of C. lanei and A. leptos and males of D. iguape have an isometric growth, while in M. microlepis, K. heylandi, females of D. iguape and P. harpagos and C. lanei males have positive allometric growth. The species S. barbatus, P. harpagos and A. leptos females have negative allometric growth. The reproductive period of the species presented its highest peak in the rainy season, except for P. harpagos and the females of M. microlepis. The species D. iguape, K. heylandi and S. barbatus presented peaks of food intensity throughout the year, H. multifasciatus, and females of C. japuhybense and A. leptos presented their highest peak in the dry period, while the others presented in the rainy season. The relative condition factor of D. iguape, C. japuhybense, P. harpagos, A. leptos and S. barbatus, males of H. multifasciatus and females of C. lanei was higher in the rainy season, while M. microlepis, K. heylandi, H. multifasciatus females and C. lanei males had the highest relative condition factor peaks in the dry period. The study showed that there was no relationship between the limnological variables and the average relative condition factor of the species in the coastal streams of Itatinga Village, in Bertioga.