Diet and resource sharing by two Pimelodidae species in a Southeastern Brazilian reservoir

Abstract

Fish can vary their diet and feeding dynamics according to biotic and abiotic factors. There is insufficient knowledge regarding these factors in reservoirs, which limits the management of these areas. The aim of this study was to determine the diet of two related and most collected fish species, verify the influence of biotic and abiotic factors on their diet, and also verify the existence of resource sharing by them in an upstream Brazilian reservoir. Fish abundance in the reservoir was calculated and data were provided by 176 specimens of Iheringichthys labrosus (Lütken, 1874) and 255 specimens of Pimelodus maculatus Lacépède, 1803 collected in Camargos reservoir, MG, Brazil. Stomach contents were analysed through the frequency of occurrence and volumetric methods. PERMANOVA analysis was done to evaluate the influence of biotic (Species and Size class) and abiotic factors (Season and Site) on the diets. The Alimentary Index (AI) and feeding overlap Index (Pianka) were also estimated. A NMDS analysis was conducted to visualize the food categories responsible for interspecific difference. The ingested items were grouped into 18 categories, of which 17 were found in both species. Feeding resources were significantly related to the biotic (Species: Pseudo F = 2.583, P = 0.001; Size Class: Pseudo F = 1.646, P = 0.001) and abiotic (Season: Pseudo F = 2.458, P = 0.006) factors. I. labrosus showed an invertivorous diet while P. maculatus an omnivorous diet and both species were not exclusively benthophagus as typically reported. Food overlap occurred intraspecifically and interspecifically (Pianka 0.61 to 0.97 and 0.61 to 0.66, respectively) and overlap also occurred in three of the four analysed seasons (Pianka 0.66 to 0.91). The diet overlap found between two of the most fished species and the low fish productivity may indicate the limitation of resources in this reservoir and should be considered for management of this area.

Integrative taxonomy reveals hidden cestode diversity in Pimelodus catfishes in the Neotropics

“…Members of the species‐richest genus of the Pimelodidae, that is, Pimelodus Lacepède, are small to medium‐sized catfishes that are widely distributed throughout Neotropical river basins (Ferraris, 2007; Lundberg & Littmann, 2003); they usually exhibit a diversified diet, with items such as algae, invertebrates and smaller fishes (Silva et al., 2019). Commonly called ‘mandi’, they have drawn broader attention given their economic and recreational value (Begossi et al., 2019; Lundberg & Littmann, 2003), as well as being one of the main sources of injuries to humans among accidents caused by freshwater fishes (Costa et al., 2020; Sarmiento et al., 2015).…”

Feeding strategy and morphology as indicators of habitat use and coexistence of two loricariid fishes from a Brazilian coastal stream

“…Fish coexistence, in special the one involving close related species, is an important point in the understanding of natural community organization (Wooton 1990). Information about diet and feeding strategies can reveal fundamental aspects of fish life history traits that enable species to coexist (Schoener 1974, Silva et al 2019) and maintain viable populations in the community. Feeding strategies reflect morphology and individual foraging performance (Douglas & Matthews 1992, do Carmo et al 2015 and are frequently described by those corporal characters related to fish movement (Celestino et al 2017, Conde-Saldaña et al 2017 as well as feeding tactics (Ramírez et al 2015).…”

Food Resource Sharing Among Benthic and Nektonic Stream Fish Species

“…The increased participation of water insect larvae in the food composition of fish species, regardless of their position in the water column, evidences the importance of insects for the proper functioning of ground systems adjacent to streams and to the water bodies themselves (Roque et al, 1990;Silva et al, 2019). We believe that changes in the environmental conditions of riparian vegetation would change the supply of resources, thus resulting in changes to the relationships among species which could trigger competitive exclusion and decreases in species variety (Villéger et al, 2010;Lobón-Cerviá et al, 2016).…”

“…The high dietary overlap observed may be a result of the collection period, i.e., in the dry season. Studies suggest that, during the dry season, the overlapping level is greater due to the lack of resources available during this period (Deus and Petrere-Junior, 2003;Silva et al, 2019). During the dry season, the increased consumption of allocthonous plant material is caused by the low water current flow, which enables leaves and tree trunks to accumulate along the stream, making them more available to the water community (Aquino et al, 2009).…”

“…Several fish species increase their diet range to take advantage of abundant resources available during the rainy season and resort to more specialized feeding during the dry season (Deus and Petrere-Junior, 2003;Silva et al, 2019), exhibiting a specialized trophic niche. The increased trophic plasticity enables neotropical fish to adjust their dietary habits according to variations in food supply (Balassa et al, 2004;Dala-Corte et al, 2017).…”