Interaction between breeding habitat and elevation affects prevalence but not infection intensity of Batrachochytrium dendrobatidis in Brazilian anuran assemblages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Foraging by the omnivorous crab Pachygrapsus transversus affects the structure of assemblages on sub-tropical rocky shores

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phytoplankton assemblages in a reservoir cascade of a large tropical - subtropical river (SE, Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The effect of the land use on phytoplankton assemblages of a Cerrado stream (Brazil)

OBJETIVO: Nosso objetivo foi investigar se o uso do solo do ambiente terrestre adjacente influencia a estrutura das assembleias fitoplanctônicas (composição, riqueza, diversidade e abundância) e biomassa (clorofila-a) em um riacho de Cerrado durante diferentes períodos do ano. MÉTODOS: Os trabalhos de campo foram realizados trimestralmente durante dois anos. RESULTADOS: As variáveis físico-químicas que melhor indicaram as diferenças nas condições da água foram condutividade, oxigênio dissolvido e transparência. Também houve um notável aumento na concentração de nitrogênio, fósforo e material em suspensão na água durante o verão devido aos efeitos da pluviosidade. As assembleias fitoplanctônicas foram compostas por 64 espécies. Cryptophyceae foi o grupo mais abundante, seguido por Bacillariophyceae. Para ambos os anos, a riqueza e a diversidade foram maiores durante a primavera e no outono, enquanto que a abundância do fitoplâncton e a concentração de clorofila-a foram mais elevados durante o outono e verão. A análise de agrupamento e a analise de correspondência canônica mostraram que a sazonalidade e o uso do solo são fatores importantes na estruturação das assembleias ao longo do ano. As alterações nas assembleias fitoplanctônicas ocorreram provavelmente em função da variação na intensidade e freqüência da mistura da água e da entrada de nutrientes oriundo do sistema terrestre adjacente para o aquático. CONCLUSÃO: A estrutura das assembleias fitoplanctônicas mostrou ser altamente influenciada pelo uso do solo, corroborando com a hipótese inicial do trabalho.

Influence of atypical pluviosity on phytoplankton assemblages in a stretch of a large sub-tropical river (Brazil)

This study aimed to evaluate the influence of alterations in pluviosity and ecological variables on microphytoplankton (> 20 mu m) structure (composition, richness, diversity, and abundance) and its biomass (chlorophyll-a), comparing different regions in a stretch of the low Igua double dagger u River and in some tributaries. Phytoplankton was sampled in 10 stations (5 in Igua double dagger u River and 5 in tributaries) during a dry period (April/2004) and an atypical rainy period (June/2004). The conductivity showed significant difference among the sampling points. Temperature, dissolved oxygen, pH, silicate, and nitrate showed significant differences between the dry and wet periods. Phytoplankton was composed of 149 taxa, and the most representative class was Chlorophyceae (71 taxa), followed by Bacillariophyceae (35 taxa), and Cyanophyceae (25 taxa). During the rainy period, stations of Igua double dagger u River showed higher taxa number and total density compared to the tributaries, but the values were similar in the dry period. Tributaries presented higher diversity and equitability in both periods. Except by two stations in Igua double dagger u River, the higher taxa number, densities and biomass occurred in the dry period, associated to low levels of suspended matter. The canonical correspondence analysis indicated the dominance of Bacillariophyceae and Chrysophyceae in the rainy period related to nitrate and suspended matter. Two other groups were observed in the dry period: one formed by Cyanophyceae, Dinophyceae, and Rhodophyceae, related to temperature and nitrite and other by Euglenophyceae and Chlorophyceae related to total phosphorus and silicate. The groups suggest adequate conditions of the physical, chemical and climatic factors to the establishment of the algae classes. Phytoplanktonic assemblages responded quickly to the environmental regional variations under strong influence of pluviosity, while in the dry period, homogeneity among stations and environmental variables was observed. The importance of climatic events is relevant in ecological studies in a temporal scale.

Importance of lateral lagoons for the zooplankton assemblages (Cladocera and Copepoda) in a large tropical reservoir.

This study aimed to analyze the composition and the ecological attributes of the zooplankton assemblages (Cladocera and Copepoda), in four marginal lagoons and in the main channel of Rosana Reservoir (SE Brazil). Fieldwork was carried out in September and November/2004 and January, March, May and August/2005. A total of 72 taxa were identifed (55 cladocerans and 17 copepods). Seasonally, a signifcant higher richness was observed during the rainy period. The lateral lagoons, compared to the reservoir, and the rainy period, compared to the dry one, showed higher zooplankton abundance. Copepods exhibited higher abundance than cladocerans. Among the copepods, there was a higher abundance of nauppli forms in the lateral lagoons and in the dry period. Calanoida dominated in relation to Cyclopoida. The most numerous cladoceran family was Bosminidae, followed by Daphniidae. The results showed that the zooplankton assemblages are infuenced by the meteorological factors, by some important nutrients (indirectly) and by the phytoplankton abundance. This pattern indicated that in the lateral lagoon system the communities are controlled by bottom-up mechanisms. The results validate the hypotheses that lateral lagoons have a prominent ecological role for the zooplankton of Rosana Reservoir and also evidenced the main driving forces infuencing the composition and ecological attributes of the assemblages. The incorporation of the reservoir lateral lagoons in regional environmental programs should be a target strategy for the conservation of the aquatic biota, mitigating the negative impact of the dam.

Tendency towards homogenization in fish assemblages in the cascade reservoir system of the Tiete river basin, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Spatio-temporal segregation and size distribution of fish assemblages as related to non-native species occurrence in the middle rio Doce Valley, MG, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Spatial and temporal distribution of tadpole assemblages (Amphibia, Anura) in a seasonal dry tropical forest of southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of the environmental heterogeneity of breeding ponds on anuran assemblages from southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Identification of key microhabitats for fish assemblages in tropical Brazilian savanna streams

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fish assemblages in stream stretches occupied by cattail (Typhaceae, Angiospermae) stands in Southeast Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Community structure of aquatic insects (Ephemeroptera, Plecoptera, and Trichoptera) in Cerrado streams of Paraguay, Paraná, and São Francisco river basins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relics of eclogite facies assemblages in the Ceara Central Domain, NW Borborema Province, NE Brazil: Implications for the assembly of West Gondwana

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phytoplankton assemblages in lateral lagoons of a large tropical reservoir

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)