Lisandro Juno Soares Vieira

Effects of flood regime on the diet of Triportheus curtus (Garman, 1890) in an Amazonian floodplain lake

We analyzed the diet of Triportheus curtus in Lake Amapa on the Acre River (AC - Brazil), during three distinct phases of the hydrological cycle (pre-flooding, flooding, and post-flooding stages). The flooding occurred between January and June of 2009. Samples were collected monthly from October 2008 through September 2009. After collection (at 19:00, 01:00, 07:00, and 13:00 hs) and taxonomic identification, fish were eviscerated and their stomachs preserved in a 4% formalin solution for later analysis. The diet was evaluated by the Index of Relative Importance (IRI), and temporal variations (pre-flooding, flooding, and post-flooding) in the diet were summarized by an ordination technique (DCA). The diet of T. curtus was comprised of several orders of insects and microcrustaceans. In the pre-flooding stage, more than 62% of the diet consisted of Ostracoda. In the flooding phase, T. curtus fed mainly on Chaoboridae larvae (Diptera) (44.3%) and terrestrial insects (fragments) (33.7%). In the post-flooding phase, Chaoboridae comprised 80% of the diet. These results indicate that the utilization of food resources by T. curtus was variable, changing with alterations in the availability of resources, as influenced by the hydrological cycle. The population of T. curtus proved to be opportunistic, changing its diet in the course of the hydrological cycle.

Concordance between macroinvertebrate communities and the typological classification of white and clear-water streams in Western Brazilian Amazonia

In this study we have attempted to answer whether there is correspondence between aquatic macroinvertebrate communities and the typological classification of white and clean-water streams in western Amazonia lowlands. We worked within two distinct hydrographic basins: Moa River catchment (clear-water streams) and Azul River catchment (white-water streams) in Serra do Divisor National Park, Acre State, Brazil, sampling 10 streams in each basin. A total of 2,952 individuals were collected, distributed among 134 taxa. Our results show that macroinvertebrate communities, at genus as well as family level, are in concordance to a priori classifications that distinguish between white and clear water streams. The main implication of our results for biomonitoring is that biotic variation between white and clear streams can be partitioned regionally, which would improve the bioassessment accuracy of the Amazonian streams.

Effects of fragments and landscape characteristics on the orchid bee richness (Apidae: Euglossini) in an urban matrix, southwestern Amazonia

Orchid bees are important pollinators in tropical forests. Although studies have already detected effects of habitat loss and forest fragmentation on bee assemblages, little is known about orchid bees in urban forest fragments. The aim of this study was to analyse the influence of forest fragments (size and edge index) and landscape features (forest cover area and built-up area around the forest fragments, connectivity and spatial distance from the urban center) on the abundance, richness and composition of orchid bees. Male bees were attracted by odoriferous baits and collected in ten forest fragments of different sizes. In total, we collected 3166 male bees belonging to 4 genera and 38 species. The increase of the built-up area and the reduction of the forest cover area around the forest fragments decreased the abundance and richness of bees. We recorded a smaller number of bees in areas closer to the urban center. We failed to find a significant relationship between abundance/richness of bees and forest fragment area, edge index, and connectivity. We observed that the faunistic dissimilarity was positively correlated with the geographic distance between forest fragments. The forest fragments that presented greater landscape dissimilarity also presented greater faunistic dissimilarity. Our results suggest that the matrix structure around the forest fragments is an important factor that influences the Euglossini bee assemblages inside these forest fragments. Based on our results, we believed that the conservation of fragments with a larger forest cover area and smaller built-up areas around them contribute to the maintenance of the diversity of orchid bees and their pollination services.