Feeding patterns, trophic structure and damming rivers effect: studies applied in freshwater environments in the Brazilian semi-arid region

Abstract

The knowledge of the fish trophic structure has been outstanding for providing relevant information on the functioning of the ecosystem in which they are inserted, mainly in dammed environments of semiarid regions that suffer constant changes in the level of water, resulting in alterations, especially in the feeding of the fish due to the variation of the food resources throughout the year, causing changes in the diet of the local ichthyofauna. Within this context, the objective was to describe the trophic categories of fish species in freshwater environments of the Rio Grande do Norte state. Seven trophic guilds were recorded: Detritivore/iliophagous, Insectivorous, Carcinophagous, Piscivorous, Herbivorous and Omnivorous. Through the results, it is observed that the fish species inserted in different environments of the state present the same food pattern, demonstrating flexibility on the diet, prevailing a generalist alimentary habit.

Changes in diet of a neotropical cichlid in response to river damming

“…Then, considering that hydrological changes can affect prey availability and composition (Loureiro-Crippa & Hahn, 2006;Pereira et al, 2016), it is expected that a polyphagous predator alter the feeding composition to equalize its energy and nutrient needs. In this context, our results corroborate the presuppositions of adjust of feeding for L. araguaiae in response to environmental change caused by river damming, as observed for many other fish species (Mérona et al, 2003;Hahn & Fugi, 2007;Pereira et al, 2016;Wang et al, 2016;Oliveira et al, 2018). In the same way, the maintenance of niche breadth pattern along studied time reinforces that the changes in diet composition is not accompanied by diversity of used prey.…”

“…Matter entering the system in the higher reaches, that is not processed locally, must be carried downstream and fully utilized by the communities along the river so that the dynamics of the system as a whole remain in equilibrium. Thus, the construction of dams along a river changes the natural dynamics of the system causing disturbances that alter the trophic chain, and only the species with higher dietary plasticity can adapt to the new conditions (Pereira et al, 2016;Oliveira et al, 2018). In this context, L. araguaiae -like other cichlids (Baumgartner et al, 2012) -is the species that seems to be relatively well adapted to the impacts caused by the formation of the reservoir.…”

“…Many species present wide trophic adaptability and are therefore generalists, meaning that they are potentially capable of using a broad range of food resources. In fact, in dammed rivers, many species change the diet following changes in resource availability (Mérona, Vigouroux, & Horeau, 2003;Hahn & Fugi, 2007;Pereira et al, 2016;Wang, Li, Xu, & Gu, 2016;Oliveira et al, 2018). Thus, the study of fish feeding habits provides fundamental information about the autoecology of the species and, in impacted environments, can show how anthropogenic activities influence the systems (Delariva, Hahn, & Gomes, 2007;Souza & Lima-Junior, 2013).…”