Feeding habits of Rachoviscus crassiceps (Teleostei: Characidae) in a coastal Atlantic rainforest stream, southern Brazil

Feeding habits of Rachoviscus crassiceps were investigated. Samples were collected between April 2003 and January 2004 in a black water stream of the coastal Atlantic rainforest in southern Brazil. The diet, evaluated by qualitative and quantitative methods, included microcrustaceans, aquatic and terrestrial insects, algae, organic matter and arachnids. Large individuals feed mainly on terrestrial insects, aquatic immature insects (larvae and pupae) and filamentous algae, whereas small fish feed basically on aquatic immature insects and microcrustaceans. The species presented an invertivorous feeding habit, and its diet in the studied stream was composed of autochthonous (mainly aquatic immature insects) and allochthonous (mainly terrestrial insects) material. © 2007 by Verlag Dr. Friedrich Pfeil, München, Germany

Catálogo de otólitos de Gerreídae (Osteichthyes-Perciformes) do litoral do Estado do Paraná, Brasil

Sagitta otholits were described for samples of Diapterus rhombeus, Eucinostomus argenteus, Eucinostomus gula, Eucinostomus melanopterus and Eugerres brasilianus. The geometrical shape, the type and margin's shape, and the otholits structures were observed. The morphometrical measurements included the lenghts and the heights of the studied otholits and their structures. The different genus and species examined presented some specific characters. According to those characters, a sistematic key was established to help in the identification of the species of the Gerreidae through its otholits.São descritos e ilustrados os otólitos sagitta de exemplares de Diapterus rhombeus Eucinostomus argenteus E. gula E. melanopterus e Eugerres brasilianus. Foram observados para os otólitos a forma geométrica, os tipos e formas das margens, tipo e forma do sulco acústico e de suas estruturas. A morfometria abrangeu os comprimentos do otólito, do óstio, da cauda e da área posterior, as alturas do otólito, das áreas dorsal e ventrai, da excisura e a largura da cauda. Entre os caracteres examinados, foram comuns aos gêneros e espécies estudadas: o comprimento maior que a altura, sulco acústico nítido, ostial e heterosulcóide; óstio deltóide e mais profundo que a cauda; cauda curva ou em gancho; colo presente; altura da área dorsal sempre menor que a da área ventral; estria inferior presente, originando-se na porção posterior da cauda; depressão superior presente, longitudinal e acompanhando a borda dorsal do sulco acústico. Ex cisura presente e com entalhe (exceto em exemplares adultos de Diapterus rhombeus). Com base nos caracteres examinados foi desenvolvida uma chave que visa facilitar a identificação específica dos Gerreidae através de seus otólitos

Thresholds of freshwater biodiversity in response to riparian vegetation loss in the Neotropical region

Protecting riparian vegetation around streams is vital in reducing the detrimental effects of environmental change on freshwater ecosystems and in maintaining aquatic biodiversity. Thus, identifying ecological thresholds is useful for defining regulatory limits and for guiding the management of riparian zones towards the conservation of freshwater biota. Using nationwide data on fish and invertebrates occurring in small Brazilian streams, we estimated thresholds of native vegetation loss in which there are abrupt changes in the occurrence and abundance of freshwater bioindicators and tested whether there are congruent responses among different biomes, biological groups and riparian buffer sizes. Mean thresholds of native vegetation cover loss varied widely among biomes, buffer sizes and biological groups: ranging from 0.5% to 77.4% for fish, from 2.9% to 37.0% for aquatic invertebrates and from 3.8% to 43.2% for a subset of aquatic invertebrates. Confidence intervals for thresholds were wide, but the minimum values of these intervals were lower for the smaller riparian buffers (50 and 100 m) than larger ones (200 and 500 m), indicating that land use should be kept away from the streams. Also, thresholds occurred at a lower percentage of riparian vegetation loss in the smaller buffers, and were critically lower for invertebrates: reducing only 6.5% of native vegetation cover within a 50-m riparian buffer is enough to cross thresholds for invertebrates. Synthesis and applications. The high variability in biodiversity responses to loss of native riparian vegetation suggests caution in the use of a single riparian width for conservation actions or policy definitions nationwide. The most sensitive bioindicators can be used as early warning signals of abrupt changes in freshwater biodiversity. In practice, maintaining at least 50-m wide riparian reserves on each side of streams would be more effective to protect freshwater biodiversity in Brazil. However, incentives and conservation strategies to protect even wider riparian reserves (~100 m) and also taking into consideration the regional context will promote a greater benefit. This information should be used to set conservation goals and to create complementary mechanisms and policies to protect wider riparian reserves than those currently required by the federal law. © 2020 British Ecological Societ