Relações tróficas entre Carnegiella marthae Myers, 1927, C. strigata (Günther, 1864) e Gnathocharax steindachneri Fowler, 1913 (Ostheichthyes: Characiformes) em igarapés próximo ao Lago Amanã - Amazonas - Brasil

Abstract

This study had as objective to analyze the trophic relationships and the possible existence of an aggressive mimicry relation involving Carnegiella strigata, C. marthae and Gnathocharax steindachneri, in firm land streams. The collects have happened in November, 2002; March and August, 2003 and they were performed in Amanã Sustainable Development Reserve (RDSA). Were captured 943 fish, and C. marthae represented 79,4%, C. strigata 3,2% and the G. steindachneri 17,4%. About 30 samples of each species were studied what concerns diet, from the stomach content analysis. For that, the degree of fullness, related volume and occurrence frequency of food were checked. Furthermore, it was calculated the feeding index to each type of food and food strategic graphs were elaborated. Similarities analysis and species diets overlap percentage were also performed 8 order taxa of the insects: Collembola, Homoptera, Lepidoptera, Ephemeroptera, Hemiptera, Hymenoptera, Diptera, Coleoptera and scales of fish, insect remains and vegetation remains. The high consumption of terrestrial and aquatic insects demonstrates a dependency of these species what concerns flooded forest. Carnegiella marthae included seven food items in the diet, while C. strigata nine and the G. steindachneri 12. Carnegiella strigata and G. steindachneri have consumed up to three different items per stomach, indicating a more expert individual food strategy. There was a low diet overlap of the species Carnegiella strigata and C. marthae in relation to Gnathocharax steindachneri. However, the diet overlap between two species of Carnegiella was relatively high (16%), what could explain the syntophic occurrence, suggesting a possible competitive exclusion case. There weren t signs of aggressive mimicry occurrence among the studied species.