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Estrutura populacional e aspectos reprodutivos de Potamorhina latior (Characiformes: Curimatidae) (Spix, 1829) dos lagos tributários do Rio Acre-Amapá e Pirapora
(Universidade Federal de São Carlos, 2002-05-09) Freitas, Francisca Estela Lima; Peret, Alberto Carvalho; https://lattes.cnpq.br/0995579236780271
The aim of this work is a comparative study of the populations of Potamorhina latior (Characiformes: Curimatidae) (Spix. 1929) in the Amapa and Pirapora lakes, located in municipality of Rio Branco, seeking to gather data about structural and reproductive aspects as well as their interrelations with the environment. The initial presuposition was the both populations would show diffrent structures, due to the strong process of anthropomorphization affecting the Amapa lake, but not yet observed in the Pirapora lake. The data were collected in the periodo from April 2000 to March 2001, and comprised climatological, limnological and fish population variables expected to provide information on possible interrelations or differences between the populations. The results showed that the climatological variables kept the same pattern of unifomity observed in earlier years, but the wareer features were remarkably diffrent concerning transparency, turbidity, dissolved oxygen and conductivity. They also exhibited important diffrences in the population composition in the two lakes: the number of fish was much larger in the Pirapora; the males outnumbered the females in both lakes, though the difference was statiscally relevant only in the Amapa; the females achieved higher values in length and average weight in both lakes; both males and females in Pirapora were bigger and heavier. Moreover, in the Pirapora lake fish size for the first maturation was smaller even to males and females, and the same relation was maintained concerning size and reproduction maturity for all individuals considered. In the analysis of species fecundity conducted with females from Pirapora, diameter basis for oocytes elimination during egg laying was 0,40 mm, and fecundity ranged from 33,843 to 140,198 oocytes. Spawning was of the total type, occurring in the rainy season, probably between December and February, in accordance with observed reproductive effort defined by gonadosomatic index. According to the results found mainly for the Pirapora population, ther seems evident the need for developing further studies with this species to obtain more and deeper knowledge of its biology.
Alimentação de Potamorhina latior (Spix, 1829) (Characiformes: Curimatidae) e Anodus elongatus (Agassiz, 1829) (Characiformes: Hemiodontidae) em lagos marginais do Rio Acre-Amapá (AC) e Pirapora (AM)
(Universidade Federal de São Carlos, 2002-05-09) Aranguren, Ligia Célia Neri; Peret, Alberto Carvalho; https://lattes.cnpq.br/0995579236780271
This study analyzesthe feeding habits and behavior of Potamorhina latior (Spix, 1829) (Characiformes: Curimatidae) and Anodus elongatus (Agassiz, 1829) (Characiformes: Hemiodontidae) in two oxbow, of the river Acre, the Amapá lake in the state of Acre and Pirapora lake in the state of Amazonas. During the period from March os 2000 to April of 2001, fish samples in the two lakes were taken and their stomach contents analyzed in order to determine their feeding habit, the preferred items in their diets, the quantitative dynamics of feeding and the similarity between the two species diets, and also to verify the relation of their diets with the seasonal variations of abiotic factors and pluviometric variations. The results showed strong differences in the diets of the species. According to the analyses of feeding frequencies, volume and indices, Potamorhina latior preferred debris followed by algae and invertebrates in the two environments both during the dry and flooding seasons. Debris represented 90% of the stomach contents, and the species can be classified as detritivorous. The same analyses carried out with Anodus elongatus revealed that the items that presented the highest frequencies in occurrence and volume were algae and zooplankton in the two lakes during both seasons, which leads to classifying the species as planktivorous. According to the distribution of algae, Euglenophyceae and Cyanophyceae predominate in the Amapa lake, while Euglenophyceae and Cholophyceae predominated in the Pirapora lake. In the case of zooplankton , Rotifera was the most representative. Spatial and seasonal variations in the diets of both species revealed little relevance, and the oscillation in the proportion of feeding items were related with their availability in the environment. Intensive feeding activity was observed in the flooding period