Distribution of periphytic algae in wetlands (Palm swamps, Cerrado), Brazil.

The distribution of periphytic algae communities depends on various factors such as type of substrate, level of disturbance, nutrient availability and light. According to the prediction that impacts of anthropogenic activity provide changes in environmental characteristics, making impacted Palm swamps related to environmental changes such as deforestation and higher loads of nutrients via allochthonous, the hypothesis tested was: impacted Palm swamps have higher richness, density, biomass and biovolume of epiphytic algae. We evaluated the distribution and structure of epiphytic algae communities in 23 Palm swamps of Goiás State under different environmental impacts. The community structure attributes here analyzed were composition, richness, density, biomass and biovolume. This study revealed the importance of the environment on the distribution and structuration of algal communities, relating the higher values of richness, biomass and biovolume with impacted environments. Acidic waters and high concentration of silica were important factors in this study. Altogether 200 taxa were identified, and the zygnemaphycea was the group most representative in richness and biovolume, whereas the diatoms, in density of studied epiphyton. Impacted Palm swamps in agricultural area presented two indicator species, Gomphonema lagenula Kützing and Oedogonium sp, both related to mesotrophic to eutrophic conditions for total nitrogen concentrations of these environments.

Periphytic desmids in Corumbá Reservoir, Goiás, Brazil: genus Cosmarium Corda.

With the objective of investigating the taxa of Cosmarium, four collection stations along the Corumbá Reservoir were set up. This resulted in the first work done on the genus in the State of Goiás. The collections of the material, of the epilithon type, were carried out in July 1996 and in the period between December 1996 and July 1997. The samples were preserved with 0.5% acetic lugol. The qualitative analysis was done by optical microscopic on non-permanent slides. Twenty-one taxa of the Cosmarium were described, each one illustrated by means of a camera lucida attachment.

Periphytic desmids in Corumbá Reservoir, Goiás, Brazil: genus Cosmarium Corda

Foram estabelecidas quatro estações de coleta com o objetivo de realizar um levantamento dos táxons do gênero Cosmarium no reservatório de Corumbá ao longo do sistema. Assim, este é o primeiro levantamento do gênero para o Estado de Goiás. As coletas do material, tipo epilíton, foram realizadas em julho de 1996 e no período de dezembro de 1996 a julho de 1997. As amostras foram preservadas com lugol acético 0,5. Para análise qualitativa das amostras foram utilizadas lâminas temporárias com o auxílio de microscopia óptica. Ao todo, foram descritas 21 espécies de Cosmarium, sendo que para cada uma delas foram realizadas ilustrações em câmara clara e comentários taxonômicos, sempre que necessário.