Abstract
Abstract Aim This study aimed to investigate the diet of seven species of fish that consume predominantly benthic macroinvertebrates, and the availability of these organisms in the environment. We analyzed the occurrence of trophic segregation between species and the correlation between the abundance of macroinvertebrates in the diet and in the environment. Methods Fish and macroinvertebrates were sampled in three streams of the Pirapó River basin (Upper Paraná River - Brazil). Differences in diet composition between species were tested using a multivariate permutation analysis of variance (PERMANOVA). A Spearman Correlation was performed to test the relation between the abundance the macroinvertebrates consumed and those available in the environment. Results All species mainly consumed aquatic insect, and significant interspecific variations in diet composition were found for most of them. For five out of the seven species of fish analyzed no significant correlation was detected between the abundance of macroinvertebrates in the environment and in the diet. Conclusions The results showed that most of the species segregate and their diets are not positively correlated with the abundance of preys in the environment, indicating that the most consumed macroinvertebrates were not the most abundant in the environment. These results suggest that the fish species select the macroinvertebrates, and that the morphological and behavioral characteristics of both predators and prey are important in feeding fish from streams.
Highlights
The optimal diet of a predator is considered to be the positive balance between the energy spent in the search and capture of the prey and the energy obtained in its consumption (MacArthur & Pianka, 1966), and this concept is used in the attempt to explain patterns in the use of food resources
Aim: This study aimed to investigate the diet of seven species of fish that consume predominantly benthic macroinvertebrates, and the availability of these organisms in the environment
The use of several sites to evaluate the diet of the species increases the variation of the available food items allowing the identification of food preferences (Asanka et al, 2015)
Summary
The optimal diet of a predator is considered to be the positive balance between the energy spent in the search and capture of the prey and the energy obtained in its consumption (MacArthur & Pianka, 1966), and this concept is used in the attempt to explain patterns in the use of food resources. The predator-prey relationship, with respect to food preference, seems to vary between species with different feeding habits, for piscivorous and zooplanctivorous fish, for example, the diet is mainly associated with the abundance and size of prey (Cantanhêde et al, 2009; Lopez Cazorla et al, 2011). Streams have a highly‐diversified macroinvertebrate fauna, represented by several phyla, such as Arthropoda, Mollusca, Annelida, Nematoda and Platyhelminthes (Melo & Froehlich, 2001) Among these groups, the class Insecta has the highest abundance and number of species (Allan, 1995; Buckup et al, 2007; Rezende et al, 2011)
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