Leandro Gonçalves Oliveira

Diversity and structure of Ephemeroptera, Plecoptera and Trichoptera (Insecta) assemblages from riffles in mountain streams of Central Brazil

The diversity and structure of Ephemeroptera, Plecoptera and Trichoptera (EPT) assemblages in streams of Central Brazil (Serra dos Pireneus, Pirenopolis, State of Goias) was investigated. Abundance data of EPT were obtained in Central-West Brazilian streams in order to evaluate the effect of spatial variability, including the effect of size of the stream and anthropic action, and seasonality (dry and rainy seasons) on faunal diversity and structure. The immatures were collected with circular sieves (0. 5 mm mesh) during one hour at five collection stations over 14 months. From a spatial point of view, the data showed that anthropic action determined the patterns of diversity whereas the size of streams (1st and 3rd-4th orders) determined the faunistic composition. In addition, environmental seasonality was an important factor for structuring the EPT fauna.

Phytoplankton diversity (alpha, beta, and gamma) from the Araguaia River tropical floodplain lakes (central Brazil)

Alpha, beta and gamma are three components of species diversity. Knowing these attributes in floodplain lake phytoplankton communities is vital when selecting conservation areas. Species diversity is commonly used with other taxonomic groups, but rarely with phytoplankton. We compared the number of phytoplankton species (alpha diversity) from 21 Middle Araguaia River floodplain lakes in the 2000 and 2001 rainy and dry seasons. From these samples we estimated complete survey species richness (gamma diversity), quantified differences in species composition between lakes (beta diversity) and assessed the influence of abiotic variables on beta diversity. We recorded a total of 577 taxa. The Sjack1 estimator indicated that 62.31% of taxa were sampled in the 2000 rainy and 67.65% dry seasons, and 68.36% in the 2001 rainy and 73.5% dry seasons. In almost all seasons, alpha diversity negatively correlated with latitude. Beta diversity (β-1) was higher in high water periods, especially in 2000. This may have been caused by isolated heavy rainfall, which would have increased environmental heterogeneity and raised beta diversity. DCA showed differences in phytoplankton composition between rainy and dry seasons in 2000 and 2001, reflecting the influence of flood pulses on phytoplankton composition. The Mantel test indicated spatial distribution patterns where geographically more distant lakes had less-similar phytoplankton communities.

Ecologia de comunidades de insetos bentônicos (Ephemeroptera, Plecoptera e Trichoptera), em córregos do parque ecológico de Goiânia, Goiás, Brasil

Relationships among some abiotic factors (temperature, velocity, flow, conductivity, oxy-reduction potential and pH) and the seazonal density of benthic insects (immature forms) of the orders Ephemeroptera, Plecoptera and Trichoptera at the Parque Ecologico de Goiânia, Goias are studied. An area of 1m2 was sampled and abiotic factors were recorded in 4 sites from August/1994 to July/1995. The faunistic composition was 75% Ephemeroptera, 1% Plecoptera and 24% Trichoptera. The data suggest the water velocity and flow as the main factors that determined the aquatic insects abundance.

Importance of environmental factors for the richness and distribution of benthic macroinvertebrates in tropical headwater streams

Abstract: An understanding of the interactions among local environmental factors (e.g., physical habitat and water quality) and aquatic assemblages is essential to conserve biodiversity in tropical and subtropical headwater streams. We evaluated the relative importance of multiple physical and chemical habitat variables that influence the richness of Ephemeroptera, Plecoptera, and Trichoptera (EPT) assemblages in wadeable Brazilian Cerrado (savanna) streams. We sampled macroinvertebrate assemblages and quantified physical and chemical habitat in 79 randomly selected sites in 2 Cerrado basins in southeastern Brazil. The environmental variables selected by multiple regression models (MLRs) via corrected Akaike Information Criteria (AICc) contributed significantly to variation in EPT taxon richness. The variance explained by physical-habitat variables was slightly greater in the Upper São Francisco Basin (adjusted R 2 = 0.53) than in the Upper Araguari Basin (adjusted R 2 = 0.46), and both were greater than the variance explained by a combined basin model (adjusted R 2 = 0.39). Physical-habitat variables were more important than water-quality variables in structuring EPT genera in streams with catchments dominated by agriculture or pasture land uses. Regional models can be improved by incorporating basin-specific information to refine biological assessments and to provide better understanding of the interactions that maintain biodiversity in stream networks.

Natural history of three Hydropsychidae (Trichoptera, Insecta) in a "cerrado" stream from northeastern São Paulo, Brazil

The faunal composition of the Hydropsychidae (Trichoptcra) of Pedregulho Stream is presented. Feeding habits of larvae and behavioural aspects of both larvae and adults are described.

Environmental Factors Influencing Distribution and Abundance of Trichopteran Larvae in Central Brazilian Mountain Streams

The relationship among environmental factors, such as temperature, velocity, flow, conductivity, pH, vegetation cover, stream order, precipitation, and human influence was studied in terms of their effects on the spatial and temporal distribution and abundance of trichopteran larvae in streams of the Pireneus mountains of Goiás State, Brazil. Samples were collected over one year. Canonical correspondence analysis suggested that vegetation cover and stream order were the main determining factors concerning distribution. The effect of rainfall on abundance of trichopteran larvae was not the same at all stations and varied with season.

Ecologia de comunidades das larvas de Trichoptera Kirby (Insecta) em dois córregos de primeira ordem da Serra dos Pireneus, Pirenópolis, Goiás, Brasil

The Trichoptera fauna in two first-order streams of Serra dos Pireneus. Goias State, was studied from June/1993 to July/1994. The Trichoptera larvae abundances were lower in the rainy season in the two streams. The temporal distributions of the functional groups (feeding categories) was similar in both streams. The ordination by Detrended Correspondence Analysis (DCA) detected a higher temporal heterogeneity of the Trichoptera community in one of the sampling stations, probably associated with higher discharge variation. There is a large variation of abundance of some genera between the two studied streams.

Stonefly (Plecoptera) fauna of streams in a mountainous area of Central Brazil: abiotic factors and nymph density

The stonefly (Pleeoptera) nymphs of streams of the Almas River basin, Pirenopolis, Goias State, Central Brazil, and some abiotie factors that might affect their temporal distribution were studied. Nymphs were sampled monthly (June 1993 to July 1994) in five stations with a Surber sampler, and each sample consisted of 20 units totalling 2 m2. In each station, stream velocity, discharge, temperature, electrical conductivity and pH were measured in order to assess their influence on the density of nymphs. Nymphs were identified to genus level. In general, the annual variation in density of nymphs, in four stations, showed that the seasonal variation was not clearly influenced by the annual rain cycle. In the case of the one of the stations, where numbers of stonefly nymphs were low and the anthropic action high, there was a density peak in the rainy season. This peak was probably related to dilution of the organie pollution in the rainy season, improving the environmental conditions for the Pleeoptera.

Stonefly (Plecoptera) fauna in a mountainous area of Central Brazil: composition and adult phenology

A survey of the stonefly (Plecoptera) fauna of streams of the Almas River basin, Pirenopolis, Goias State, Central Brazil, is presented as well as data of some factors that could affeet the temporal distribution of the adults. For checking adult phenology, light sources were used in three stations from June 1993 to Jully 1994. The sampled individuais were identified to species or morphospecies, as possible. In this study, 301 individuais belonging to the perlid genera Anacroneuria Klapalek, 1909, Kempnyia Klapalek, 1916 and Macrogynoplax Enderlein, 1909 were collected. Adults of most species were collected along the studied period, except for those of Kempnyia that were restricted to the warm-rainy season, the same pattern for this genus in southeastern Brazil. Although adults of most species were collected along most of the studied period, the largest number of adults was collected in the months with larger mean temperatures, showing a clear seasonality in abundance.

Taxonomic key for the genera of Elmidae (Coleoptera, Byrrhoidea) occurring in Goiás State, Brazil, including new records and distributional notes

A taxonomic key for the genera of Elmidae (Coleoptera, Byrrhoidea) occurring in Goias State, Brazil, including new records and distributional notes. Despite their great diversity and high abundance in Neotropical aquatic environments, the fauna of Elmidae remains practically unknown in some areas and even entire biomes in this region. In this work we bring, for the first time, faunistic data for the Elmidae of central Brazil. The aim of this work was to inventory the Elmidae fauna in central, southwestern and southeastern Goias State, Brazil and to produce a taxonomic key, at genus level, for adults from the studied region. The taxonomic key presented herein offers means for the identification of all the 13 genera known to occur in Goias, 11 of them being new records for the State. Moreover, the number of named species registered for Goias increased from one to nine.