Browsing by Author "Collares-Pereira, M.J."
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- Feeding behaviour of Barbus Bocagei assessed under a spatio-temporal approachPublication . Collares-Pereira, M.J.; Martins, M.J.; Pires, A.M.; Geraldes, Ana Maria; Coelho, Maria M.The feeding behaviour of Barbus bocagei was assessed in a lowland system by a two years survey Of two contrasting sites also talking into account, for the first time diurnal changes of fish diet and benthos availability.
- Preliminary insight into age and growth of the Iberian chub (Leuciscus pyrenaicus) in the sorraia systemPublication . Geraldes, Ana Maria; Collares-Pereira, M.J.An investigation of age and growth in the Iberian chub Leuciscus pyrenaicus Gunther, 1868 revealed a seasonal growth pattern, with annulus formation restricted to a short period of the year (May/June). Maximum ages were 6+ for both sexes. During and after the third year females grew at faster rates than males, and the most important decrease in growth rates occurred between age I! and Ill in males and between age Ill and IV in females. Mean back-calculated standard lengths of III and IV age classes were significantly higher in the River Sorraia. Mean weights of I and II age classes were higher in Sor stream whereas the individuals from III ad IV age classes were heavier in the River Sorraia. Shifts in growth rates arc discussed in relation to seasonal and spatial variations in the environmental conditions as well as to sexual maturity.
- Régime alimentaire et croissance du barbeau iberique Barbus bocagei dans la reviere Sorraia (Portugal)Publication . Geraldes, Ana Maria; Coelho, Maria M.; Collares-Pereira, M.J.Le barbeau ibérique Barbus bocagei est l’une des espèces les plus représentatives de l’icthyofaune de la rivière Sorraia (Bassin du fleuve Tejo). L’objectif de cette étude est de déterminer 1) les variations spatiales du régime alimentaire et de croissance linéaire de cette espèce entre différentes stations du sous-bassin de la Sorraia et 2) les variations de ces paramètres sur l’échelle temporelle dans deux de ces stations.
- Riparian ecotones and spatial variation of fish assemblages in Portuguese lowland streamsPublication . Collares-Pereira, M.J.; Geraldes, Ana Maria; Magalhães, M.F.; Coelho, Maria M.The first results of a long-term study on the role of riparian ecotones on the population and community dynamics of Iberian stream fish are presented and discussed . Riparian and macrophyte cover, bank slope and depth were among the most important variables affecting fish distribution . In general small fish favoured shallow areas with high macrophyte cover, whereas large fish dominated in deep areas with a high riparian cover . Slight spatial changes in terrestrial prey use were found suggesting a minor role for this resource during autumn . Finally, no significant spatial differences were found for linear growth, although some differences were obtained for the condition factor