Abstract
The aim of this work was to characterise the population of Trichomycterus sp. in Passa Cinco stream, regarding length structure, sex ratio, diet and reproductive aspects, in accordance with drought and rainy season periods and longitudinal gradient, as well as to analyse its corporal condition in a temporal dimension. Six samplings were accomplished with the use of electric fishing equipment in three different sites in Passa Cinco stream, contemplating sites of order two, three and four, during the months of May, July, September and November of 2005; and January and March of 2006. Three hundred and forty one individuals were captured, composed of 203 males, 99 females and 39 immatures. The smallest captured individual, an immature, presented 28 mm of standard length and the largest, a male, 85 mm. There was not significant variation in repletion degree and accumulated fat in the visceral cavity of the individuals analysed during the considered periods. Eleven different food items were found in the stomach contents. Considering the whole sampling period, immature Diptera was a preferential item and other items were found as occasionally ingested. Spearman and Friedman tests did not find significant differences in the diet of Trichomycterus sp. in the periods and sampling sites, respectively. The average of absolute fecundity was of 73 oocytes, and the parceled type of spawning was performed. Both males and females of Trichomycterus sp. presented significant differences in their corporal conditions in the considered periods, and in the rainy season, these fishes were in better condition.
Highlights
IntroductionTrichomycteridae catfish comprise approximately 226 species (de Pinna and Wosiacki, 2003) of smallsized fishes (de Pinna, 1998) which in general, inhabit small water courses with rocky river beds, strong currents and clear waters (Arratia, 1983; de Pinna 1998), which results in a high degree of endemism within the family (Costa, 1992; de Pinna, 1992; Bizerril, 1994).Species of the Trichomycterus Valenciennes in Humboldt, 1832 genus are widely distributed in the neotropical area (de Pinna 1998; Román-Valencia, 2001) and, in agreement with Wosiacki (2005), a real estimate of species diversity of this genus is far from being completed, because many species have been recently described, for example: T. catamarcensis (Fernández and Vari, 2000), T. yuska (Fernández and Schaefer, 2003), T. maracaya (Bockmann and Sazima, 2004), T. trefauti (Wosiacki, 2004), T. guaraquessaba (Wosiacki, 2005), T. tupinamba and T. jacupiranga (Wosiacki and Oyakawa, 2005). a substantial amount of work exists on stream fishes, there are still few studies that deal with the biology of the species, concerning the feeding, reproduction or dynamics of those populations (Braga, 2006), considering that often those environments are possessors of endemic ichthyofaunas. Castro (1999) emphasises the need for studies in freshwater systems of small-sized fishes which involve systematisation, evolution and biology.Works that deal with the biology and ecology of Trichomycterus species are still few
A substantial amount of work exists on stream fishes, there are still few studies that deal with the biology of the species, concerning the feeding, reproduction or dynamics of those populations (Braga, 2006), considering that often those environments are possessors of endemic ichthyofaunas
Works that deal with the biology and ecology of Trichomycterus species are still few
Summary
Trichomycteridae catfish comprise approximately 226 species (de Pinna and Wosiacki, 2003) of smallsized fishes (de Pinna, 1998) which in general, inhabit small water courses with rocky river beds, strong currents and clear waters (Arratia, 1983; de Pinna 1998), which results in a high degree of endemism within the family (Costa, 1992; de Pinna, 1992; Bizerril, 1994).Species of the Trichomycterus Valenciennes in Humboldt, 1832 genus are widely distributed in the neotropical area (de Pinna 1998; Román-Valencia, 2001) and, in agreement with Wosiacki (2005), a real estimate of species diversity of this genus is far from being completed, because many species have been recently described, for example: T. catamarcensis (Fernández and Vari, 2000), T. yuska (Fernández and Schaefer, 2003), T. maracaya (Bockmann and Sazima, 2004), T. trefauti (Wosiacki, 2004), T. guaraquessaba (Wosiacki, 2005), T. tupinamba and T. jacupiranga (Wosiacki and Oyakawa, 2005). a substantial amount of work exists on stream fishes, there are still few studies that deal with the biology of the species, concerning the feeding, reproduction or dynamics of those populations (Braga, 2006), considering that often those environments are possessors of endemic ichthyofaunas. Castro (1999) emphasises the need for studies in freshwater systems of small-sized fishes which involve systematisation, evolution and biology.Works that deal with the biology and ecology of Trichomycterus species are still few. Trichomycteridae catfish comprise approximately 226 species (de Pinna and Wosiacki, 2003) of smallsized fishes (de Pinna, 1998) which in general, inhabit small water courses with rocky river beds, strong currents and clear waters (Arratia, 1983; de Pinna 1998), which results in a high degree of endemism within the family (Costa, 1992; de Pinna, 1992; Bizerril, 1994). A substantial amount of work exists on stream fishes, there are still few studies that deal with the biology of the species, concerning the feeding, reproduction or dynamics of those populations (Braga, 2006), considering that often those environments are possessors of endemic ichthyofaunas. Works that deal with the biology and ecology of Trichomycterus species are still few. Some aspects of diet and/or reproduction are known for T. aerolatus (Manriquez et al, 1988; Huaquín et al, 2002; Habit et al, 2005 and Scott et al, 2007), T. caliensi (RománValencia, 2001), T. chaberti (Pouilly and Miranda, 2003), T. chiltoni (Scott et al, 2007), T. corduvense (Marraro et al, 2005), T. itacarambiensis (Trajano, 1997) and two other species are still not resolved taxonomically (Casatti, 2003 and Chará et al, 2006)
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