Dieta de <em>Astyanax asuncionensis</em> (Characiformes, Characidae), em riachos da bacia do rio Cuiabá, Estado do Mato Grosso

Abstract

RESUMO. A dieta de Astyanax asuncionensis, em riachos da bacia do rio Cuiabá, Estado do Mato Grosso, durante períodos de chuva e seca, foi descrita, sendo suas variações associadas ao grau de integridade da vegetação ciliar. Para isso, foram realizadas amostragens mensais, entre janeiro e dezembro de 2003, em quatro riachos, com o emprego de pesca elétrica. Foram analisados 213 estômagos, e a dieta foi descrita por meio das porcentagens de ocorrência e volume, combinados ao Índice Alimentar (IAi). Os aspectos da dieta abordados consistiram na composição, na origem dos recursos e na amplitude do nicho alimentar (Índice de Levins). O espectro alimentar incluiu 22 itens, sendo que os recursos alóctones dominaram, principalmente insetos, independente do local e período. A amplitude do nicho alimentar foi, em geral, maior no período de chuva. Os resultados obtidos mostraram que essas populações de A. asuncionensis são sustentadas por recursos de origem terrestre, especialmente Hymenoptera e demonstram a importância da mata ciliar no aporte de alimento. Considerando que os riachos apresentam diferentes graus de degradação da mata ciliar, estes resultados indicam que a manutenção da vegetação e a recuperação das áreas degradadas é condição altamente relevante para manutenção desta espécie nestes riachos.Palavras-chave: Astyanax asuncionensis, dieta, amplitude do nicho, bacia do rio Cuiabá.ABSTRACT. Diet of Astyanax asuncionensis (Characiformes, Characidae), in streams of the Cuiabá river basin, Mato Grosso State. The goal of this study was to assess the diet of A. asuncionensis in four streams. Fish samples were carried out monthly from January to December 2003, using electrofishing. Stomach contents of 213 individuals were analyzed, and the diet was described as for occurrence and volumetric percentage of each item combined in a feeding index (IAi). The diet composition, importance of allochthonous and autochthonous resources, and diet breadth (Levin's index) were assessed among streams and between seasons (dry and rainy). The diet was composed of 22 feeding items; allochthonous resources (especially insects) dominated the diet in all streams and in both seasons. The highest values of diet breadth were recorded, in general, during the rainy period. These results showed that A. asuncionensis populations are supported by terrestrial food (especially Hymenoptera), indicating the importance of riparian vegetation. Considering that streams differ according to riparian vegetation cover, our results indicate that the maintenance of vegetation and recovery of degraded areas are essential for conservation of this fish species in these streams.

Longitudinal and ontogenetic changes in feeding patterns of an insectivorous Crenuchidae in streams of southern Brazil

“…This highlights their significance in sustaining healthy fish populations and an overall ecosystem balance (Wesner 2012). The significance of riparian vegetation for fish diet is well recognized in various studies (Gomiero and Braga 2008, Borba et al 2008, Ferreira et al 2012, Souza and Lima-Junior 2013, Silva et al 2014, Leite et al 2015. These comparisons suggest a pattern in the classification of the genus Characidium within trophic guilds, regardless of the sampling location (in the state of Brazil) or seasonality/time (year) in which the fish are captured.…”

No effects of macroconsumer exclusion on macroinvertebrate functional composition in Brazilian karst streams along a gradient of riparian forest loss

“…The availability and diversity of alternative resource such as fruits from tropical riparian vegetation (Correa & Winemiller, 2018; Nogueira et al., 2023; Reys et al., 2009) and terrestrial insects (Borba et al., 2008) could have contributed to the limited effect of the macroconsumers on the FFG among benthic macroinvertebrates that rely on inputs of riparian leaf litter. In addition, in disturbed streams, insectivorous macroconsumers such as sculpins and darters are often replaced by generalist algivorous and omnivorous macroconsumers especially minnows and sunfishes (Schofield et al., 2008).…”

“…Aquatic insects and gastropods were the most common benthic grazers (Corrêa et al., 2019). The fish fauna was dominated by insectivorous predators such as Xenurobrycon macropus (Synbranchidae) and Astyanax asuncionensis (Characidae) (Borba et al., 2008; Corrêa et al., 2019; Graciolli et al., 2010).…”

Ontogeny of feeding by Astyanax paris in streams of the Uruguay River Basin, Brazil

“…Protection of its habitats should consider not only the environmental quality of the streams, but also the integrity of adjacent riparian vegetation. The importance of riparian vegetation to fish diet is well recognized and documented for the allochthonous feeder Astyanax species (Gomiero and Braga, 2003;Borba et al, 2008;Ferreira et al, 2012;Souza and Lima-Junior, 2013;Silva et al, 2014;Leite et al, 2015). Conserving the streams is also important for those autochthonous feeders (Cavalheiro and Fialho, 2016).…”