Ictiofauna da bacia do Rio Mundaú: dieta e morfologia do trato digestório de cinco espécies da família Characidae

Abstract

Brazilian freshwater ichthyology studies are concentrated at south and southeastern regions. Northeastern region is deficient in studies, especially Middle Eastern northeastern hydrographic micro region. Existing ones focus on small parts of larger regions or reservoirs. Food resources availability vary throughout the year, and fish need to adopt new strategies to acquire food. In these circumstances, some species may present digestive tracts variations as answer to these variations in quality and availability of food. This study aims to list the species in Mundaú River Basin (chapter I) and analyses the diet of five characidae species and their relation to digestive tract morphology (gut length and pyloric caeca number). For chapter I, 35 locations along the entire basin. As for chapter II, samples were taken on two the locations cited above. Fish were captured using seine net, cast net, hand net and bottle traps. Five of these species had their stomach contents analyzed. Mundaú River Basin has 55 species, distributed on 50 genus, 31 families and 10 orders. 30 species are strictly freshwater, seven are estuarine and 18 marine. Three species (Hemigrammus guyanensis, H. rodwayi e Poecilia sarrafae) are new occurrences for Middle Eastern Northeastern region. Besides, two cynolebbiids species, Hypsolebias sp. and Anablepsoides cearensis, the second one being classified as critically endangered by IUCN. Diet were composed mostly of algae, vegetable fragments, aquatic insects and micro crustaceans. Only one species is carnivorous, three are herbivorous and one is omnivorous, what indicates the importance of vegetable items to species maintenance. The relationship between diet and the number of pyloric cecum were not verified in three of the five species, therefore, there was not enough evidence to confirm correlation with the number of cecum and food preference.