Carla Ferreira Rezende

Feeding ecology of Hypostomus punctatus Valenciennes, 1840 (Osteichthyes, Loricariidae) in a costal stream from Southeast Brazil

In the present study we aimed to compare the feeding ecology of Hypostomus punctatus from a coastal stream from Southeast Brazil with data previously published for the same study site before environmental changes. Feeding preferences were assessed through a sample of 138 specimens (67 from the dry and 71 from the rainy season) using the Index of Alimentary Importance (IAi). We registered five different food items (detritus, plant fragments, Diatoms, Chloroficeae and Cianobacteries) composing the species diet. Detritus was the most abundant one both during the rainy and dry seasons (IAirainny = 90.34 and IAidry = 96.30). No significant differences were registered for the volume of food items consumed during the rainy and dry seasons. The Frequency of Occurrence analysis showed that four (detritus, plant fragments, Diatoms and Chloroficeae) among the five all other consumed ones, were always frequent. Comparing our own results with those available for the study site, we suggest that the feeding habit of H. punctatus has changed according to environmental changes and that the species diet is strongly dependent upon environmental conditions.

Niche enlargement as a consequence of co-existence: a case study

Spatio-temporal changes in the diet, niche breadth and niche overlap of two species of Characidium from three different sites along a Neotropical coastal stream were studied during a dry and rainy season. Seasonal changes were restricted to the occurrence of plant items in the stomach contents. The relative importance of food items in the diet of both species varied across sites, but Diptera, Ephemeroptera, Simuliidae, Trichoptera and Coleoptera larvae were always the main prey items. Contrary to the expected pattern, values of the niche breadth were higher at the site where Characidium species co-existed and niche overlapped at this site indicated 52% (p = 0.52) of feeding overlap.

A DIVERSIDADE FUNCIONAL DOS PEIXES: PUBLICAÇÕES EM COMUNIDADES DE RIACHO

Em diversos ramos da ecologia, os estudos sobre diversidade funcional cresceram e ganharam mais espaco e importância. As caracteristicas locais do habitat, fatores ambientais e a disponibilidade de recursos influenciam a organizacao funcional das comunidades. Os grupos funcionais nas comunidades de peixes estao relacionados aos recursos disponiveis no ambiente e podem estar sempre mudando, ja que riachos sao ambientes instaveis e sujeitos a constantes variacoes fisicas. Nesta revisao, destacamos a importância da aplicacao de indices de diversidade funcional na caracterizacao da organizacao funcional de uma comunidade.