Valéria de Oliveira Fernandes

Structure of the periphytic algae community in natural substratum of the lagoon of the Federal University of Espírito Santo, Brazil

The present study aimed at evaluating the structure of the periphytic algae community in Panicum rivulare Trin. and to relate it with some environmental variables of the lagoon of the Federal University od Espirito Santo, an artificial environment that receives domestic effluent in natura . The samplings had been carried monthly through one site sampling during eight months (October, 2001 to May, 2002). The community was evaluated through its main attributes: abundant and dominant species, frequency of occurrence, diversity, eveness, richness and population density. The determined environmental variables had been: salinity, electric conductivity, turbidity, transparency, depth, euphotic zone, pH, dissolved oxygen, water and air temperature and precipitation. The periphytic algae community was composed by 36 taxa, distributed in seven classes. The predominant class, qualitatively, was Chlorophyceae, followed of Cyanophyceae and Bacillariophyceae, being the less representative Oedogoniophyceae, Zygnemaphyceae, Euglenophyceae and Dinophyceae class. Chlorophyceae predominated quantitatively in the majority of the samplings and associated with the salinity, being Coelastrum microporum the only dominant species in the four first samplings. Water temperature and light had influenced the too much class, mainly Cyanophyceae and Bacillariophyceae. The results showed that the variation of the community structure was resulted of autogenic changes, reflected in the substitution of the species standard, throughout the studied period, in reply to the temporal variation of the environmental variable’s also influencing in the diversity and richness. Key words: algae, macrophyte, temporal variation.

Phytoplankton at the lagoon of the campus of the Universidade Federal do Espírito Santo (Vitória, ES, Brazil): community structure and ecological considerations

A lagoa da Universidade Federal do Espirito Santo e um ambiente artificial, criado com finalidade de harmonia paisagistica, apesar de, durante varios anos, receber efluentes domesticos in natura de edificacoes circundantes dentro do proprio campus . O presente estudo visa avaliar a estrutura da comunidade fitoplanctonica e relaciona-la com algumas variaveis fisicas e quimicas da agua e climatologicas da regiao, em uma estacao amostral, durante oito meses (outubro/2001 a maio/2002), em intervalos mensais. O fitoplâncton foi avaliado atraves de seus principais atributos (riqueza, dominância, abundância e frequencia de ocorrencia de especies e densidade populacional, alem da diversidade e equitabilidade). As variaveis ambientais determinadas foram: pH, oxigenio dissolvido, condutividade eletrica, salinidade, turbidez, transparencia, zona eufotica, profundidade da coluna d’agua, precipitacao e temperatura (do ar e da agua). Para testar a significância entre as variaveis biologicas do fitoplâncton e as variaveis ambientais e ordena-las utilizou-se, respectivamente, o coeficiente de correlacao de Spearman e a ACP Foram registrados 34 taxons, distribuidos em quatro classes. A classe predominante, qualitativamente, foi Chlorophyceae, seguida de Cyanophyceae e Bacillariophyceae, sendo a classe Dinophyceae menos representativa. A classe Chlorophyceae predominou quantitativamente, representada apenas pela Ordem Chlorococcales. Cyanophyceae e Bacillariophyceae apresentaram flutuacoes temporais de suas respectivas densidades associadas a temperatura da agua. A precipitacao, a transparencia e a temperatura da agua foram as variaveis abioticas que mais influenciaram na estrutura do fitoplâncton da lagoa da UFES, evidenciando variacao temporal da comunidade mostrada pela ACP. Palavras-chave: variacao temporal, lagoa artificial, fitoplâncton, estrutura da comunidade.

Water quality of a coastal lagoon (ES, Brazil): abiotic aspects, cytogenetic damage, and phytoplankton dynamics

Assessment of water resources requires interdisciplinary studies that include multiple ecosystem aspects. This study evaluated the water quality of Juara Lagoon (ES, Brazil) based on physical and chemical variables, cytogenetic responses in Allium cepa and phytoplankton dynamics. Three sampling sites were defined and water samples were collected during two sampling periods. Analyses such as determination of photic zone, conductivity, and concentrations of nutrients and metals were conducted as well as cytotoxic, mutagenic, and genotoxic potentials using A. cepa test. The main attributes of phytoplankton community, such as total richness, total density, density by class, dominance, and diversity, were also evaluated. Results have revealed that Juara Lagoon has signs of artificial eutrophication at two sampling sites due to high levels of total phosphorus and ammonia nitrogen. Cytotoxic, genotoxic, and mutagenic potentials were detected as well as high concentrations of Fe and Mn. Furthermore, 165 phytoplankton taxa were recorded, with highest richness in Chlorophyceae and Cyanophyceae classes. In addition, Cyanophyceae presented as the highest density class. A. cepa test and phytoplankton community evaluation indicated that the ecological quality of Juara Lagoon is compromised.