Search

Habitat complexity can substantially alter trophic relationships, such as competitive and predatory interactions, between fish species. This study aimed to evaluate how trophic interactions between congeneric fish species (Serrapinnus calliurus, S. heterodon and S. notomelas) are affected by habitat complexity provided by macrophytes. The following predictions were tested: (1) the composition of the diets of congeneric fish species differs between high- and low-complexity habitats and between habitats of the same category; (2) species show higher trophic niche breadth in sites with greater habitat complexity; and (3) trophic niche overlap between congeneric species pairs is low in macrophyte stands because of greater food availability. Sampling was conducted between November 2011 and July 2012 in five floodplain lakes of the Baía River, a tributary of the upper Paraná River. The degree of habitat complexity was categorised as high (with macrophytes) or low (without macrophytes). The stomach contents of the three species sampled from sites of high- or low-complexity habitat were analysed. Diet variation depended on habitat complexity. The median trophic niche breadth of the three congeneric species was low, but their diets showed higher variability in sites of high-complexity habitat. Significant differences in trophic niche overlap were observed in two species pairs when comparing sites of high- and low-complexity habitat. Habitat complexity directly affected trophic interactions between the fish species, which may favour their coexistence through trophic niche segregation. Our study emphasises the importance of habitat complexity in mediating trophic interactions between congeneric species and clarifies the coexistence of ecologically similar fish species. [ABSTRACT FROM AUTHOR]

This study investigated the feeding habits of Serrapinnus microdon andS. calliurus and possible seasonal differences (rainy and dry seasons) in the utilization of food. The fish were collected monthly in Cancela stream, in the basin of the Manso/Cuiabá rivers in the State of Mato Grosso, from March 2003 to February 2004. Both speciespreferentially consumed resources of autochthonous origin, independently of the season. The diet of S. microdon was basically composed by immature forms of aquatic insects, with Chironomidae and Ephemeroptera predominating during the entire study period, thus showing a restricted diet (Ba = 0.27 in the rainy season, and 0.29 in the dry season). For S. calliurus, aquatic insects (especially Ephemeroptera) were equally important, but algae and detritus were also prominent depending on the season, showing a less specialized diet (Ba = 0.44 in the rainy season, and Ba = 0.48 in the dry season). Both fish species presented a benthivorous feeding habit; however, everything indicates that they live together without competition, because the food on which they depend is widely available. Serrapinnus calliurus was susceptible to seasonal changes in the availability of food resources.Este estudo teve por objetivo investigar o hábito alimentar de Serrapinnus microdon e S. calliurus e possíveis diferenças sazonais (estações de chuva e seca) na utilização do alimento. Os peixes foram coletados mensalmente no riacho Cancela, bacia dos rios Manso/Cuiabá, Estado do Mato Grosso, entre março de 2003 e fevereiro de 2004. Ambas as espécies consumiram preferencialmente recursos de origem autóctone, independente da estação considerada. A dieta de S. microdonfoi composta essencialmente por formas imaturas de insetos aquáticos, detacando-se Chironomidae e Ephemeroptera durante todo o período de estudos, apresentando, assim, uma dieta restrita (Ba = 0,27 na chuva e 0,29 na seca). Para S. calliurus inseto aquático (especialmente Ephemeroptera) foi igualmente importante, mas destacaram-se tambémalgas e detrito, dependendo da estação considerada, apresentando dieta menos especializada (Ba = 0,44 na chuva e Ba = 0,48 na seca). Ambas apresentaram hábito alimentar bentívoro, porém, tudo indica que convivam sem competição, uma vez que o alimento do qual dependem é amplamente disponível. Serrapinnus calliurus mostrou-se mais susceptível às alterações sazonais na disponibilidade dos recursos alimentares.

This study investigated the feeding habits of Serrapinnus microdon and S. calliurus and possible seasonal differences (rainy and dry seasons) in the utilization of food. The fish were collected monthly in Cancela stream, in the basin of the Manso/Cuiabá rivers in the State of Mato Grosso, from March 2003 to February 2004. Both species preferentially consumed resources of autochthonous origin, independently of the season. The diet of S. microdon was basically composed by immature forms of aquatic insects, with Chironomidae and Ephemeroptera predominating during the entire study period, thus showing a restricted diet (Ba = 0.27 in the rainy season, and 0.29 in the dry season). For S. calliurus, aquatic insects (especially Ephemeroptera) were equally important, but algae and detritus were also prominent depending on the season, showing a less specialized diet (Ba = 0.44 in the rainy season, and Ba = 0.48 in the dry season). Both fish species presented a benthivorous feeding habit; however, everything indicates that they live together without competition, because the food on which they depend is widely available. Serrapinnus calliurus was susceptible to seasonal changes in the availability of food resources.

Copyright of Acta Scientiarum: Biological Sciences is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)