Trophic structure of the fish community in the reservoirs and tributaries of the Middle and Lower Tietê River (São Paulo, Brazil)

welber senteio smith


Abstract: Aim: We investigated the use of food resources along the reservoirs of the Middle and Lower Tietê and tributaries. Methods: We compared diet data of 27 fish species present in reservoirs and tributaries of the medium and lower Tietê. Results: In the analysis of the stomach contents, 40 types of food items were found, being 29 autochthonous and 11 allochthonous. It was observed that the predominant diet of the species in the tributaries was constituted by terrestrial insects, followed by vegetal material, seeds, crustaceans and mud, whereas in the reservoirs the main diet consisted of aquatic insect, vegetal material, seeds and scales. The species of fish analyzed were grouped into 13 trophic categories. In both reservoirs and tributaries, the predominant diet was carnivorous, whereas the omnivorous diet occurred only in the reservoirs. Species in rivers specialize more in certain resources and in reservoirs are more generalist, which makes a better survival condition possible. In both the tributaries and in the reservoirs the fish consumed, more frequently, aquatic and terrestrial insects, scales, fish, crustaceans, superior vegetables and algae. In the tributaries the most consumed items were scales, filamentous algae and terrestrial invertebrates, considering that in these environments there is a greater availability of resources. In the reservoirs, the most consumed item was Ephemeroptera (aquatic insect). Conclusions: Both fingerlings and adults use the coastal areas of the reservoirs and even the tributaries to feed on superior plants and insects that have terrestrial and aquatic stages. The trophic characteristics exhibited by the fish in the reservoirs depend on the structuring of the community during the colonization process, the particular characteristics of each reservoir, the introduction of exotic species of fish and other food resources.

Keywords: Diet; feeding habits; trophic categories; seasonal variation.


Dieta; hábito alimentar; categorias tróficas; variação sazonal.

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