Abstract
AimResource partitioning has been recognized as a major driver affecting fish communities, with the potential to reduce interespecific competition. This is the result of differences in feeding apparatuses and feeding mode, location of the fish species in the water column and swimming ability, as well as type and size of prey and its availability. The present study surveys a highly limited aquatic system in semi-arid Brazil with regard to habitat and food availability, with very low diversity of fish, and poor in underwater habitat structures and prey, with the objective of understanding resource partitioning among fish species under such conditions.MethodsThree species of Cichlidae (Pisces: Perciformes) were sampled during the dry and wet seasons and had their stomach contents analyzed to evaluate food consumption. The resource partition among fish species was evaluated based on Pianka’s niche overlap index and tested for significance against null models.ResultsIt was observed a low overlap among the study species in food resource use, with individuals tending to specialize to select some food items. This is likely the result of low natural variation in abundance of specific food items associated with fish preferences (both morphological and behavioral).ConclusionsThese results support evidence that, in Brazilian semi-arid aquatic systems, coexistence of fish species seems to be enhanced by the partition of food items at specific trophic levels. Within this context, flow variability would have a key hole in fish coexistence by promoting a high diversity of aquatic habitat elements available for colonization of fish and their prey. Furthermore, food resources available to fish play an important role in this dynamics since prey foods are expected to vary in abundance as the habitat changes.
Highlights
The fish fauna of Brazilian semi-arid aquatic systems is diverse with the presence of innumerous endemic species (Rosa et al, 2003; Maltchik & Medeiros, 2006)
We evaluate the diets of three species of cichlid fish, Oreochromis niloticus (Linnaeus, 1758), Parachromis managuensis (Günther, 1867) and Geophagus brasiliensis (Quoy & Gamard, 1824) with the aim of understanding resource partitioning among these species under conditions of limited food availability
Aquatic systems in the tropics are known for their variety of fish species, adapted to consume food resources from a range of different sources (Lowe‐Mcconnell, 1987)
Summary
The fish fauna of Brazilian semi-arid aquatic systems is diverse with the presence of innumerous endemic species (Rosa et al, 2003; Maltchik & Medeiros, 2006). Long-term programs of introduction of exotic species of fish, such as the Cyprinus carpio Linnaeus 1758 and Cichla ocellaris Bloch & Schneider, 1801 (Gurgel & Oliveira, 1987) in these artificial reservoirs have contributed to the degradation of the natural biodiversity in aquatic environments in semi-arid Brazil. In systems where there are few food items, generalist strategies would be expected (Roughgarden & Feldman, 1975). In this context, a restricted food spectrum, that is, the preference for few food items, would not be advantageous for freshwater fish in systems highly subjected to water level changes, since the same food items will not be available during the entire hydrological cycle (Agostinho et al, 2007). A restricted food spectrum, that is, the preference for few food items, would not be advantageous for freshwater fish in systems highly subjected to water level changes, since the same food items will not be available during the entire hydrological cycle (Agostinho et al, 2007). Zaret & Rand (1971), for instance, demonstrate that the partitioning in food resource use is more effective, or evident, during periods of food scarcity, which highlights the importance of food availability in its partition by fish species
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