No abstract

Sedimentological studies are the baseline to understand estuary contamination or pollution since the sedimentary characteristics are responsible for controlling and governing metals and nutrients distribution over the estuary. Hence, our main objective was to evaluate the sedimentary characteristics of the tide-dominated Mocajuba estuary located on the eastern Amazon coast, based on the sediment deposit dynamics (i.e., granulometry; hydrodynamics, and deposition of organic matter content and calcium carbonate). Granulometric, Cluster, and Principal Components Analysis was carried on classifying and identifying groups of sediments across the estuary. Three cluster groups and two environments (marine and estuary) were recognized. Cluster 1 represents the marine environment located at the mouth of the estuary, with a predominance of fine sandy sediments. This type of sediment is supplied

In this study, through a rapid assessment, we evaluated differences in richness, abundance, species composition and beta diversity of Euglossini bees in preserved areas and areas altered by riverine human populations in the Caxiuanã National Forest (northern Amazon). Our hypotheses were: i) the species richness, diversity, abundance and composition of Euglossini bees differ between the preserved and altered areas because many species are intolerant to small anthropic disturbances; and ii) areas altered by riverine populations have higher values of beta diversity (species dissimilarity between sites) than preserved areas, due to local changes in habitat and increased heterogeneity between sites. We sampled two areas (preserved and altered) and, in each area, four transects were sampled with odorous baits. We used a Student’s t test to evaluate differences in richness, abundance, and Shannon-Wiener diversity index. We also evaluated differences in composition and differences in beta diversity between areas. We collected 102 specimens, identified in 18 species and three genera, 63 individuals (61.8% of the total) in preserved areas and 39 individuals (38.2%) in altered areas. Euglossa liopoda (Dressler, 1982) was the most abundant in altered areas and Euglossa imperialis (Cockerell, 1922) the most abundant in preserved areas. Species richness was 2.5 times greater in the transects of preserved areas, and species composition also differed between the sampled areas. In contrast, species abundance did not differ between transects of both areas. Despite our small sample size, this study demonstrated that the richness, composition and beta diversity of Euglossini bees can be potentially affected by local changes in habitat caused by small-scale activities provided by traditional Amazonian groups. Our results indicate the urgency for more comprehensive studies aimed to investigate these relationships.