Aspectos da biologia alimentar do Astyanax jacuhiensis (Cope, 1894), no Rio Uruguai Médio, oeste do Rio Grande do Sul, Pampa brasileiro

Abstract

This work consists in feeding study jacuhiensis of Astyanax, which has a wide geographic distribution among countries of South America. The project aims to identify the feeding habits of Astyanax jacuhienses, found in the basin of the Uruguay River in its middle course in the city of Uruguaiana, RS, Pampa Brazilian. Referring to your eating habits, the minnows are generally omnivorous having a food preference for aquatic invertebrates. Often the stomach contents found in lambaris presents equivalent proportions of vegetables (seeds, fruits, algae, weeds) and animals (aquatic and terrestrial insects), demonstrating that this is an omnivorous species with herbivorous, insectivorous trend, which represents an opportunistic feature . There are few studies on food biology of the species in the RS West Frontier region. This work aims to contribute to the knowledge of the food habits of this species through monthly collections during the period May 2014 to April 2015. We obtained a total of 243 individuals, 132 females and 111 males, were analyzed length total (Lt), standard length (Ls) total weight (Wt), intestine length (Lti) stomach length (LTE), intestine weight (Wi) and weight stomach (We), liver weight (Wf) weight and stomach contents (Wce). It was determined the IHS (Wt / Wf) and We relations / Wt and relationship Lte / Wt. Date were analyzed using a stereomicroscope magnifying glass to determine the items that are part of the diet. We also calculated repletion index throughout the year is classified into four types of reference content volume: full, half full, half empty (1% to 10%) and empty. The executed relations the following results were obtained: degree of repletion full of females were understood in the months from April to August, achieving a peak in the months of May and August, and the repletion index full of males registered during the months from November to May obtaining a peak in February. IHS, both for males and for females indicated in months between May to August and can be observed an energy reserve to support the winter period, where it records the IHS peaks in July and August. As We / Wt and LTE / Wt relations resulted in similar data to IHS corroborating the data obtained. Regarding the analysis of stomach contents items were found: plant remains, insect debris, remains of other animals, other organs, rice and sediments. It can be concluded which in these winter months both reserve power to support the mild temperatures and also have a higher record of food in the stomach contents, but the females feed more in the winter months and the males in the summer months.