Feeding activity and influence of intraspecific competition on zooplankton communities by jundiá (Rhamdia quelen Quoy and Gaimard, 1824) in laboratory

Abstract

Experiments were designed to determine if the juvenile forms of jundia (Rhamdia quelen) exhibit selectivity feeding on zooplanktonic organisms and the influence of intraspecific competition on the diet. The fish were maintained in 5000-L containers, and after seven days from birth, they were acclimated in experimental units with different densities and supplied with water containing plankton (natural), where they remained for 24 h in the environment with food. In the first seven days at densities of 5 and 10 fish.L-1, the fish selected the Rotifera more intensely, and at densities of 20 and 40 fish.L-1, the Cladocera were more selected. At 14 days of age, the Cladocera were the most selected for all densities of fish. At 21 days of age, the juvenile forms of jundia maintained a preference for Cladocera, and there was an increase in the capture of Copepoda at a density of 40 fish.L-1. At 28 days of age, the Cladocera were the most captured at densities of 5 to 20 fish.L-1, and the consumption of copepods increased at a density of 40 fish.L-1. The juvenile forms of Rhamdia quelen showed a high feeding preference for Cladocera at all the ages tested (7, 14, 21 and 28 days), but the density of fish per litre influenced the capture of the preferential food. This study showed that the juvenile forms of jundia had a more rapid response to the presence of food at densities of more than 10 fish.L-1, and that at higher densities the fish decreased interactions of territorial defense and formed schools, which allowed the foraging of zooplanktonic organisms, larger in size, more agile and of greater energy gain, such as the Cladocera and copepods.

Trophic ecology of Acestrorhynchus falcirostris Cuvier, 1819 in island lakes on the lower stretch of the Solimões River, Amazon Basin

“…Therefore, the most consumed prey has a direct association with the morphology of the predator, availability of prey (Correa and Winemiller, 2014). However, aspects such as population density of prey (Neves dos Santos et al, 2008) and nutritional requirement of the predator (Rotta, 2003;Brandão-Gonçalves and Sebastien, 2013), can also justify the preferential ingestion of some prey.…”

Use of trophic ecology of omnivorous fish and abiotic factors as supporting tools for assessing environmental impacts in a neotropical river

“…The composition of R. quelen 's food items and categories indicates that the species is omnivorous (Brandão‐Gonçalves & Sebastien, 2013; Gomes et al, 2000; Gomiero & Souza, 2007; Kütter, 2009) although tending toward carnivory (dos Santos & Meurer, 2020; Gomes et al, 2000). The species' intestinal tract is similar to that of carnivores (Baldisserotto, 2008), and the adaptations of its mouth apparatus allow it to select prey from the bottom of the river, and crush shells (Kütter, 2009), justifying the higher percentage of fish in the stomachs.…”

“…The anthropogenically impacted environment may also be related to the size and weight of the species, which are relatively smaller than those found in other settings(Albieri et al, 2014;Froese & Pauly, 2021), probably related to the fact that eutrophication can affect species in terms of biomass variation, positively or negatively favoring some fish species(de Mutsert et al, 2016). However, even with the reduced number of captures, we were able to estimate the diet composition of the analysed species, compatible with those described in the literature.The composition of R. quelen's food items and categories indicates that the species is omnivorous(Brandão-Gonçalves & Sebastien, 2013;Gomes et al, 2000;Gomiero & Souza, 2007;Kütter, 2009) although tending toward carnivory (dosSantos & Meurer, 2020;Gomes et al…”

Characterizing functional morphology and trophic niches in a neotropical Characiforms (Actinopterygii: Teleostei) assemblage in middle Munim River basin, Maranhão, Brazil

“…Speciation in these regions often depends on factors such as niche opportunities, migratory constraints, and intricate species interactions (Garcia et al, 2020;Melo et al, 2021). Niche partitioning, as a consequence of diversification, can alleviate interspecific and intraspecific competition across trophic (Brandão-Gonçalves and Sebastien, 2013;Lubich et al, 2022), spatial or temporal niches (Gomiero et al, 2010), and is often mirrored in morphological characteristics of species (Garcia et al, 2020). dynamics of these species, ultimately contributing to the formulation of essential conservation measures necessary to address ongoing environmental changes.…”