Sirlene Aparecida Felisberto

Desmidiaceae, Gonatozygaceae e Mesotaeniaceae na comunidade perifítica do reservatório de Salto do Vau (Bacia do rio Iguaçu, PR)

The aim of this work was to inventory the species of the families Desmidiaceae, Gonatozygaceae and Mesotaeniaceae from the periphytic community of a reservoir, located in south Brazil. The samples were collected during summer and winter in the distinct regions along the river-dam bed. The substrata collected, always in the littoral region, were petioles of aquatic vegetation. In the results 45 taxa were registered, belonging to the genera Actinotaenium (1 species), Cosmarium (17), Cylindrocystis (1), Euastrum (3), Gonatozygon (1), Hyalotheca (1), Micrasterias (7), Netrium (1), Pleurotaenium (1), Spondylosium (1), Staurastrum (9), and Staurodesmus (2). Higher species richness occurred in the transition region. Euastrum denticulatum Gay and Hyalotheca dissiliens (Smith) Brebisson ex Ralfs showed 100% of occurrence, while Cosmarium abbreviatum Raciborski var. minus (West & West) Krieger & Gerloff and Pleurotaenium ehrenbergii (Brebisson) De Bary occurred in 83% of the samples.

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.

Comasiella, Desmodesmus, Pectinodesmus e Scenedesmus na comunidade perifítica em ecossistema lêntico tropical, Brasil Central

This work aimed to taxonomic study of Comasiella, Desmodesmus, Pectinodesmus and Scenedesmus of the periphytic community in tropical lentic environment. Periphyton samples were collected from petioles of aquatic plants (Cyperaceae) in the littoral area of the Samambaia reservoir, in September and November 2010 (dry season) and January and March 2011 (rainy season). We identified 19 taxa, which were distributed in Comasiella (one), Desmodesmus (14), Pectinodesmus (two) and Scenedesmus (two). Considering the occurrence of taxa in each period, 12 were recorded in the dry season and only one the rainy season, while 10 species were analyzed for both periods. The species, Comasiella arcuata (Lemmermann) var. platydisca (Smith) Hegewald & Wolf, Desmodesmus spinulatus (Biswas) Hegewald, Scenedesmus acunae Comas and Pectinodesmus pectinatus (Meyen) Hegewald & Wolf constitute first citation for the Goias State.

Dinâmica sucessional de comunidade de algas perifíticas em um ecossistema lótico subtropical

Resumoobjetivo deste trabalho foi descrever as mudancas na estrutura de comunidades de algas perifiticas durante o processo de colonizacao e sucessao, em periodo chuvoso, indicando suas especies descritoras. O local selecionado para a realizacao deste estudo foi o rio do Corvo (22°39’S, 52°46’W), um afluente do rio Paranapanema localizado proximo a barragem do reservatorio de Rosana, na regiao noroeste do Parana, Brasil. Coletas do perifiton em substrato artificial e medicoes de dados abioticos foram realizadas no periodo de 21 de novembro a 12 de dezembro de 2003, em intervalos de tres dias. A identificacao e quantificacao das algas foi feita em microscopio invertido, utilizando-se o metodo de Utermohl. Para analise da dinâmica sucessional, foram considerados: riqueza de especies, densidade total, abundância relativa dos taxons, especies descritoras, diversidade de Shannon-Wiener e equitabilidade. As flutuacoes observadas na densidade total foram determinadas principalmente por Bacillariophyceae, Chlorophyceae, Cyanophyceae e Zygnemaphyceae. Maiores valores de abundância na comunidade de algas perifiticas foram registrados para especies pequenas de diatomaceas, abundantes durante todo o periodo, consideradas colonizadores eficientes e de crescimento rapido, assim como para cianobacterias e algas verdes filamentosas (Oedogonium spp. e Stigeoclonium spp.), de crescimento mais lento e mais abundantes nos estadios tardios. As primeiras estao entre as r-estrategistas, enquanto as ultimas estao entre as C-S estrategistas (algas mais competitivas em sistemas mesotroficos e estaveis). A diversidade de Shannon-Wiener foi elevada (2,2 a 3,1), com o maior valor constatado na terceira semana de desenvolvimento sucessional. Com base em analise de componentes principais, as concentracoes de nutrientes, o pH e a turbidez foram os principais fatores abioticos relacionados ao processo de sucessao. Palavras-chave: diversidade, estrutura da comunidade, perifiton, rio, sucessao.

Euastrum and Micrasterias (family Desmidiaceae) in lentic tropical ecosystem, Brazil

This study aimed to perform the taxonomic survey of Euastrum and Micrasterias in a lentic tropical environment, seeking to contribute to the knowledge on biodiversity and geographical distribution of the Zygnemaphyceae. Conducted at the Samambaia Reservoir, ten samples were collected in the dry season (24/09/10 and 04/11/10) and ten in the rainy season (06/01/11 and 02/03/11). Periphyton was sampled from stems of aquatic plants (Cyperaceae), which were in the marginal area of the reservoir. With the floristic survey, 22 taxa were identified representing the genus Euastrum (9) and Micrasterias (13), of these 16 are new records for the State of Goias. In relation the frequency of occurrence and the seasonal period, 19 taxa were classified in the rare category and three in common, nine species were recorded during the dry season, while four only in the rainy season.

Taxonomical and ecological characteristics of the desmids placoderms in reservoir: analyzing the spatial and temporal distribution

AIM: This study aimed to evaluate the influence of river-dam axis and abiotic factors on the composition of Closteriaceae, Gonatozygaceae, Mesotaeniaceae and Peniaceae in a tropical reservoir METHODS: Water samples for physical, chemical and periphyton analysis were collected in April and August 2002 in different regions along the axis of the river-dam of Rosana Reservoir, River Basin Paranapanema. The substrates collected, always in the litoranea region, were petioles of Eichhornia azurea (Swartz) Kunth. To examine the relationship of abiotic variables with reservoir zones and between the floristic composition of desmids, we used principal component analysis (PCA) and canonical correspondence analysis (CCA RESULTS: The results of the PCA explained 81.3% of the total variability in the first two axes. In the first axis, the variables of conductivity, water temperature and the pH were related to the sampling regions of April with higher values, while for the month of August, nitrate, total phosphorus and dissolved oxygen showed higher values. We identified 20 taxa, distributed in the genera Closterium (14), Gonatozygon (4), Netrium (1) and Penium (1). Spatially, the higher taxa were recorded in the lacustrine region for both collection periods. The canonical correspondence analysis (CCA) summarized 62.2% of total data variability of taxa in the first two axes, and in August, Closterium incurvum Brebisson, C. cornu Ehrenberg ex Ralfs and Gonatozygon monotaenium De Bary, were related to higher values of turbidity and nitrate to the lacustrine and intermediate regions CONCLUSION: Thus, the formation of groups was due to the regions along the longitudinal axis, then the seasonal period, which must be related to the low current velocity, the higher values of temperature and the water transparency, especially in late summer

Desmídias pseudofilamentosas na comunidade ficoperifítica do Reservatório de Rosana, Bacia do Rio Paranapanema, Brasil

(Pseudofilamentous desmids of the phycoperiphytic community of the Rosana Reservoir, Paranapanema River basin, Brazil). This study aimed to make an inventory species of periphytic pseudofilamentous desmids from three regions of the Rosana Reservoir, southern Brazil. Samples were collected in autumn and winter periods at different sites along the river-dam axis of the reservoir (fluvial, intermediate and lacustrine regions). The substrates (petioles of Eichhornia azurea Kunt) were collected in the littoral. Thirteen taxa of phycoperiphytic pseudofilamentous desmids (Desmidiaceae) were distributed in five genera: Desmidium C. Agardh (3), Hyalotheca Ehrenberg (1), Onychonema Wallich (3), Sphaerozosma Corda ex Ralfs (1) and Spondylosium Brebisson ex Kutzing (5). Considering both sampling periods, in the lacustrine region it was recorded the highest number of species, i.e. eight in autumn and ten in winter. Independently of the sampled period, pseudofilamentous desmids were not found in the fluvial region, well as in the intermediate region in the autumn.