Alimentação e ecomorfologia de peixes predadores em lagos de várzea amazônica

Abstract

Predator species directly or indirectly influence the aquatic biota, regulating the abundance of prey and structuring natural communities. The affinity between predator and prey, as well as intensity of predation is determined by several factors, including the morphology of predators. The morphologies of these species could be associated with its trophic ecology, depending on the structure of environments. The objective of this study was to determine the diet composition of eight species of predatory fish in lakes of the Amazonian floodplain, featuring his ecomorphological attributes in association with their feeding items. Samplings took place in May, November and December 2014. And were done at two floodplain lakes, placed into an island of the lower stretch of the Solimões River. Gill nets were used with different sizes of mesh and rod with hook and bait. Biometrics and the withdrawal of stomachs were also carried out in the field. Were estimated degree of stomach fullness, frequency of occurrence of feeding items and its importance index. A PCA was applied to order the fish by its diet. Also were made 17 morphlogical measures in each fish, generating 13 ecomorphological attributes. A PCA also was employed aiming to order the species according to these attributes. Five studied species had fish as the most important item in their diets and three had the shrimp as being more important. The first axis of the PCA associated P. squamosissimus with shrimp and P. nattereri with fruits / seeds and other, the second axis associated R. vulpinus and H. malabaricus with fish and insects and H. Scomberoides with shrimp. Three ecomorphological attributes discriminated the fish species. PCA with these attributes ordered the fish species by four groups, P. squamosissimus and C. monoculus associated with relative length of the caudal peduncle and protrusion index, A. falcirostris and H. malabaricus with relative head height and relative position of the eyes, R. vulpinus and H. Scomberoides with the mouth appearance and compression index of the caudal peduncle and P. nattereri and S. rhombeus with relative width of the head and the relative area of the eyes. The ecomorphological analysis divided the species by the ability to find the prey, swimming performance of the predator and prey size. Nevertheless, there were no significant correlation between fish morphology and feeding items