Maria do Rosário de Fátima Padilha

Seasonal changes of water quality in a tropical shallow and eutrophic reservoir in the metropolitan region of Recife (Pernambuco-Brazil)

This study investigated the water quality in an urban eutrophic reservoir in Northeastern Brazil, considering the influence of seasonality. Monthly, samples were collected in the sub-surface reservoir. The following abiotic variables were analyzed: temperature, pH, dissolved oxygen, apparent color, turbidity, conductivity, fluoride, total nitrogen, chlorides, total dissolved solids, total hardness, iron, copper, manganese, aluminum, chlorophyll-a and phaeophytin. Total and thermotolerant coliforms were analyzed according to APHA (2012). Cyanobacteria density was quantified through its biomass. The data were analyzed using one- way ANOVA and Pearson correlation test. Higher values mean phytoplankton biomass (26.3mm3.L-1) occurred in the dry season, especially Planktothrix agardhii and Geiterinema amphibium, which occurred in 100% of samples. High trophic state index was detected throughout the year. Seasonality exerted some influence on both biotic and abiotc variables, leading to changes in water quality of the reservoir.

Relação Fitoplâncton - Zooplâncton em Ambiente Oligotrófico(Fitoplankton-Zooplankton Relationship in Oligotrophic Environment)

Ecossistemas lenticos de pequeno porte respondem rapidamente as condicoes ambientais, influenciando a comunidade planctonica devido as flutuacoes bioticas e abioticas do corpo d’agua. Este estudo teve como objetivo analisar os parâmetros fisico-quimicos e a identificacao da comunidade planctonica (fitoplâncton, zooplâncton e bacterioplâncton) presentes no reservatorio, correlacionando esses organismos em um ambiente oligotrofico. As analises foram realizadas mensalmente no periodo de julho/2014 a junho/2016. A analise de todos os parâmetros fisico-quimicos e biologicos foi realizados de acordo com metodologia oficial. Empregou-se ferramentas estatisticas multivariadas (ACP) e teste de Pearson para avaliar a correlacao entre as variaveis abioticas e a biomassa total de cada grupo planctonico. Nesta pesquisa encontrou-se uma relacao positiva entre as biomassas totais da comunidade zooplânctonica e fitoplânctonica, entretanto componentes do bacterioplancton, nao foi significativo. Estes resultados indicaram que a predacao e/ou competicao nao sao relacoes ecologicas significativas entre as especies zooplanctonicas e fitoplanctonicas presentes neste ecossistema oligotrofico, existindo assim uma relacao favoravel entre os grupos estudados. Desta forma, o desenvolvimento desses organismos foi influenciado pelas mesmas variaveis abioticas (manganes, dureza e temperatura), atuando de forma direta no estabelecimento de suas biomassas. A B S T R A C T Small lentic ecosystems respond rapidly to environmental conditions, influencing the planktonic community due to the biotic and abiotic fluctuations of the water body. This study aimed to analyze the physicochemical parameters and identification of the planktonic community (phytoplankton, zooplankton, and bacterioplankton) present in the reservoir, correlating these organisms in an oligotrophic environment. The analyses were performed monthly from July/2014 to June/2016. The analysis of all physicochemical and biological parameters was carried out according to the conventional methodology. Multivariate statistical tools (PCA) and Pearsons test were used to evaluate the correlation between the abiotic variables and the total biomass of each planktonic group. In this research was found a positive relation between the total biomasses of the zooplanktonic community and phytoplanktonic. However, components of bacterioplankton were not significant. These results indicate that predation and competition are not significant ecological relationships between zooplanktonic and phytoplanktonic species present in this oligotrophic ecosystem, and there is a favorable relationship between the studied groups. In this way, the development of these organisms was influenced by the same abiotic variables (manganese, hardness, and temperature), acting directly in the establishment of their biomasses. Keywords : plankton, reservoir, abiotic factors.