Effects of flooding regime and diel cycle on diet of a small sized fish associated to macrophytes

Abstract

AIM: In this paper we assessed the effects of flooding (low and high water period) on the feeding activity and diet composition of Serrapinus notomelas in patches of the macrophyte Eichhornia azurea in a shallow floodplain lake (upper Paraná River Floodplain, Brazil). We also assessed the variations of diet composition and feeding activity along the diel cycle. METHODS: Traps were used to catch the fish inside of macrophyte patches monthly from June/2007 to May/2008. A total of 1038 stomachs were examined. We assessed the feeding activity with the mean stomach fullness degree method. To summarize and support the results of diet composition in the different periods (low and high water periods) and times (dawn, light period, and dusk), was applied a nonmetric multidimensional scaling (NMS). RESULTS: The feeding activity of S. notomelas did not differ between low and high water periods, but it differed along the diel cycle. The feeding activity was higher during the light period and dusk, at both the low and high water period. The diet composition differed significantly between low and high water periods, and also along the diel cycle. In the low water the diet of S. notomelas was composed mainly by algae and in the high water by Cladocera. Algae were consumed mainly during the light period while Cladocera in dawn and dusk. CONCLUSIONS: Our results indicate that the oscillations in the water level affect the diet composition, but not the feeding activity of S. notomelas. These seasonal changes are probably related to the temporal abundance of food resources, thus, when Cladocera density was low (low water), S. notomelas consumed mainly algae but when Cladocera was more abundant (high water), it became a common food resource.

Feeding ecology of Serrapinnus notomelas (Characiformes: Cheirodontinae) in small forest streams in the Machado River basin, Rondônia, Brazil

“…In studies involving Serrapinnus heterodon in a reservoir in the São Paulo state (Gonçalves et al 2011) and S. notomelas on a lake in the Paraná River basin (Carniatto et al 2012), it was found a high frequency of full stomachs, our study corroborate those findings. In fishes, the seasonal cycle of nutritional reserves, such as fat, follows a pattern associated with reproduction (Favero et al 2010;Freitas et al 2011;Espírito-Santo et al 2013), when fishes reduce feeding activity and use the energy stored in fat for gonadal maturation (Santos et al 2010).…”

Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

“…This condition allows ecologically similar species to coexist, and can reduces competition among them (Schoener, 1974;Correa & Winemiller, 2014;Olson et al, 2015). Habitat structure and the daily activities of the species as important factors in determining interspecific interactions may also be considered (Gelós et al, 2010;Carniatto et al, 2012;Almeida-Silva et al, 2015); these aspects were not evaluated in this study.…”

“…Inside each area, fish were captured with small seining nets (open areas) and sieves (macrophyte covered areas). Once several species may exhibit movements between open and macrophyte areas along the day (Carniatto et al, 2012), independent of the lake area, sampling was conducted in open and macrophyte areas in the lakes only to better represent the fish assemblage of each lake (Petry et al, 2003), and, therefore, the amount of food resources (herein food availability).…”

Seasonal variation in the use of food resources by small fishes inhabiting the littoral zone in a Neotropical floodplain lake

“…was algivorous. These results are explained by differences in the abundance of resources between dry and rainy periods, and by feeding habits of each species (Esteves and Galetti 1995;Russo and Hahn 2006;Neiff et al 2009;Pereira et al 2011;Carniatto et al 2012). On the other hand, except for H. eques, there were no significant differences in interindividual variation in diet between periods.…”

“…In relation to S. notomelas, algae and aquatic higher plants comprised the majority of its diet, which is probably facilitated by the fact that this species preferentially occupy macrophyte stands (Casatti et al 2003;Pelicice et al 2005;Dibble and Pelicice 2010;Carniatto et al 2012), whose submerged portions sustain a high abundance of filamentous algae (Biolo and Rodrigues 2013), which should also occur with Serrapinnus sp. The feeding habits of S. notomelas has been described as essentially algivorous (Casatti et al 2003;Pelicice and Agostinho 2006;Hahn and Loureiro Crippa 2006).…”