Chlorophyceae e Trebouxiophyceae (Chlorophyta) em ambientes lóticos na área de influência da Usina Hidrelétrica do Baixo Iguaçu, Estado do Paraná, Brasil

The presence of microscopic algae of the classes Chlorophyceae and Trebouxiophyceae in lotic environments stands out for its high morphologic diversity and its capacity to indicate the quality of the water. This study had the objective of accomplishing the taxonomic survey of rivers from the area of influence of Baixo Iguaçu’s hydroelectric power plant. The monthly samples were collected from january of 2019 to december of 2019 allowing the identification of 55 taxons, distributed in eight families Hydrodictyaceae, Scenedesmaceae, Selenastraceae, Sphaeropleaceae, Volvocaceae, Chlorellaceae, Oocystaceae and Trebouxiophyceae incertae sedis. Between the identified taxa, 12 are new citations for Paraná State: Monactinus simplex var. echinulatum (Wittrock) Pérez, Monactinus simplex var. sturmii (Reinsch) Pérez, Pseudopediastrum boryanum var. longicorne (Reinsch) Tsarenko, Desmodesmus lefevrei (Deflandre) S.S.An, T.Friedl & E.H.Hegewald, Desmodesmus opoliensis var. carinatus (Lemmermann) E.Hegewald, Desmodesmus perforatus (Lemmermann) E.Hegewald, Pectinodesmus javanensis (Chodat) E.Hegewald, Scenedesmus acunae Comas Gonzáles, Quadrigula closterioides (Bohlin) Printz, Volvox globator Linnaeus, Actinastrum aciculare f. minimum (Huber-Pestalozzi), Actinastrum hantazschii var. subtile Woloszynska.A presença de microalgas das classes Chlorophyceae e Trebouxiophyceae em ambientes lóticos se destaca por sua alta diversidade morfológica e sua capacidade de indicar a qualidade da água. Este trabalho objetivou realizar o levantamento taxonômico em rios da área de influência da Usina Hidrelétrica do Baixo Iguaçu. As amostragens mensais foram realizadas de janeiro de 2019 a dezembro de 2019 possibilitando a identificação de 55 táxons, distribuídos em oito famílias Hydrodictyaceae, Scenedesmaceae, Selenastraceae, Sphaeropleaceae, Volvocaceae, Chlorellaceae, Oocystaceae e Trebouxiophyceae incertae sedis. Dentre os táxons identificados, 12 são novas citações para o Estado do Paraná: Monactinus simplex var. echinulatum (Wittrock) Pérez, Monactinus simplex var. sturmii (Reinsch) Pérez, Pseudopediastrum boryanum var. longicorne (Reinsch) Tsarenko, Desmodesmus lefevrei (Deflandre) S.S.An, T.Friedl & E.H.Hegewald, Desmodesmus opoliensis var. carinatus (Lemmermann) E.Hegewald, Desmodesmus perforatus (Lemmermann) E.Hegewald, Pectinodesmus javanensis (Chodat) E.Hegewald, Scenedesmus acunae Comas Gonzáles, Quadrigula closterioides (Bohlin) Printz, Volvox globator Linnaeus, Actinastrum aciculare f. minimum (Huber-Pestalozzi), Actinastrum hantazschii var. subtile Woloszynska

Main predictors of phytoplankton occurrence in lotic ecosystems

Abstract: Aim Our goal was to relate the phytoplankton metacommunity to its possible determinants in a micro watershed: (I) determinants related to landscape-scale filtering, (II) determinants referring to local microhabitat filtering, (III) determinants referring to previous colonization, and (IV) determinants representing three different dispersal routes. Methods Eight sampling stations were selected along the Cascavel River watershed, located in the state of Paraná, Brazil. Samples were collected quarterly for three years. All phytoplankton samples were quantitatively analyzed to determine the density of the metacommunity. In addition, it was characterized the landscape in terms of land use and occupation, and environmental characterization in terms of physical and chemical variables of the water. All data underwent relevant statistical analysis, where variance partitioning was carried out using partial RDA models, with prior selection of predictor variables, to estimate the relative role of each predictor in the community. We also compared three possible dispersal routes: “Asymmetric Eigenvector Map” (AEM), “Overland” and “Watercourse”. Results It was found that the metacommunity was best explained by “asymmetric eigenvector mapping” (AEM), indicating that because it is a small spatial scale the high connectivity between the sampling stations enables species to disperse overland as well. The different filters act together and depend on rainfall variation. Besides fluctuating temporally, the influence of these mechanisms is subject to which dispersal hypothesis is being considered. Conclusions At the watershed scale, we argue that small-scale processes should be considered, since they homogenize the landscape and consequently leave the environmental gradient similar between sampling stations. In addition, the connectivity of colonization patches is essential to understand the behavior of microalgae that have a high dispersal capacity and are not restricted only to the river course