Rotifera from littoral and pelagic zones of Tapacurá reservoir, Pernambuco, Brazil. The rotifers of Tapacurá reservoir, State of Pernambuco, Brazil, were studied concerning the horizontal distribution in pelagic and littoral zones, in the rainy (August/2003) and dry seasons (January/2004). Qualitative and quantitative samples were carried out in nictimeral samplings in the different zones of the reservoir, with an interval of six hours in the two depths. Biotic parameters as richness, density, diversity and equitability were estimated. Similarity and Analysis of Variance (ANOVA) were also used. Twenty-eight species and two subspecies of Rotifer were found from which five species are considered new occurrences in State of Pernambuco. The littoral zone presented higher richness than the limnetic zone in both seasonal periods with nine exclusive species. The density and equitability differences between zones of the reservoir were not expressive in opposite to diversity that was higher in the littoral zone in the dry season (p<0.01). The similarity analysis indicated horizontal homogeneity of Rotifer community in the rainy season characterized by lower temperatures and higher wind velocity, and a tendency to horizontal stratification in the dry season characterized by higher temperatures and lower wind intensity. Presence of aquatic vegetation yielded peculiar features in the littoral zone. KEYWORDS.Biotic limnology, horizontal distribution, Rotifer, biodiversity, aquatic vegetation. RESUMO.Os rotíferos do reservatório de Tapacurá, Pernambuco, Brasil foram estudados quanto à distribuição horizontal nas zonas limnética e litorânea, nos períodos chuvoso (agosto de 2003) e seco (janeiro de 2004). Amostras quali-quantitativas foram obtidas através de coletas em ritmo nictimeral nas distintas zonas do reservatório, com intervalo de seis horas, em duas profundidades. Os parâmetros bióticos riqueza, densidade, diversidade e equitabilidade foram avaliados. Análises de similaridade e variância (ANOVA) também foram utilizadas. Vinte e oito espécies e duas subespécies de Rotifera foram encontradas, das quais cinco espécies são novas ocorrências para Pernambuco. A zona litorânea apresentou maior riqueza que a limnética em ambos ao período sazonais, com nove espécies exclusivas. As diferenças de densidade e equitabilidade entre as zonas do reservatório não foram significativas, ao contrário da diversidade, que apresentouse mais elevada na zona litorânea no período seco (p<0,01). A análise de similaridade revelou homogeneidade horizontal da comunidade de Rotifera no período chuvoso, caracterizado por menores temperaturas e maior velocidade do vento, e tendência à estratificação horizontal no período seco, caracterizado por temperaturas mais elevadas e menor intensidade dos ventos. A presença de macrófitas propiciou características peculiares na zona litorânea. PALAVRAS-CHAVE. Limnologia biótica, distribuição horizontal, Rotifera, biodiversidade, macrófitas. Recebido em março de 2005. Aceito em agosto de 2006. ISSN 0073-4721 Artigo...

-The aim of this study was to describe the composition and structure of cladocerans of littoral areas with and without macrophytes from a temporary shallow pond in the Caatinga of Pernambuco state (Brazil). Samples were taken between June 2011 and August 2012. The sampling of cladocerans and environmental variables was performed at four fixed points, using a plankton net (45 μm) and a multiparameter probe. Twenty-two cladoceran species were recorded, with two new occurrences for Pernambuco state: Chydorus cf. brevilabris and Macrothrix superaculeata. The species richness of non-planktonic cladocerans (16) was higher than that of planktonic ones (4). The mean density was 186.7 ± 273.6 ind. L -1 . Macrothrix elegans, Diaphanosoma spinulosum and Ephemeroporus hybridus were the most abundant. The fluctuation index of the main species showed greater instability during the driest months or greater rainfall, a pattern not observed for the environmental data. However, the pond did not show limnological and cladoceran structure differences between the dry and rainy seasons and between the areas with and without macrophytes. With the exception of temperature and rainfall, the structure and richness of cladocerans was not related to the fluctuation of the other variables. Warmer months had higher densities and richness of cladocerans. On the other hand, months of greatest rainfall had lower richness, especially for the Chydoridae family. Although this Caatinga pond is maintained exclusively by rainwater, the richness of cladocerans is high when compared to other tropical and subtropical ecosystems. These results suggest that rainfall and temperature exert greater control on the dynamics of cladocerans in the Caatinga's temporary shallow ponds, and demonstrate the importance of these ecosystems to biodiversity in the semiarid region.

The state of the art in planktonic rotifers biodiversity from some freshwater ecosystems was elaborated for the state of Pernambuco (Brazil). A bibliographic survey was done and most studies focused seasonal aspects and trophic state of the ecosystems. At least 19 continental aquatic environments related to rotifer researches have been studied. The Sertão area was the most studied. The present survey registered 64 species of planktonic rotifers, distributed in 18 families and 29 genera. The most frequent species were Keratella tropica and Brachionus falcatus, showing that most studies were done in the limnetic zone. The results showed the need for more research on the biodiversity of this group in ecosystems located in Zona da Mata and Agreste areas, as well as in lotic systems and in the littoral zones, in view of the lack of information.Keywords: Rotifera, check-list, limnic ecosystems, Pernambuco, northeast Brazil. Este trabalho apresenta uma avaliação do estado da arte da biodiversidade de rotíferos planctônicos de alguns ecossistemas aquáticos continentais para Pernambuco (Brasil). Um levantamento bibliográfico foi realizado e a maior parte das pesquisas enfocou aspectos sazonais e estado trófico dos ecossistemas. Pelo menos 19 locais foram estudados no tocante aos rotíferos. O Sertão é a região mais estudada. Nesta pesquisa foram registradas 64 espécies de rotíferos planctônicos, distribuídas em 18 famílias e 29 gêneros. As espécies mais freqüentes nos locais estudados foram Keratella tropica e Brachionus falcatus, mostrando que a maior parte dos estudos foi realizada na zona limnética. Os resultados sugerem ainda a necessidade de mais pesquisas sobre a biodiversidade deste grupo em locais localizados na Zona da Mata e no Agreste, bem como em ecossistemas lóticos e nas zonas litorâneas dos locais, tendo em vista a carência de informações. ResumoPalavras-chave: Rotifera, lista de espécies, ecossistemas límnicos, Pernambuco, nordeste do Brasil.

The study was conducted to assess the community structure of planktonic rotifers and their relation to the environmental impact of Nile tilapia, Oreochromis niloticus (Linaeus, 1758), aquaculture activities (ponds and net-tanks), associated with a Neotropical semiarid reservoir in Brazil. Our hypothesis was that the ecological attributes of the rotifer community were different when considering the influence of fish aquaculture activities. We identified 28 species, with 10 species from the Brachionidae family. The average density and diversity index of rotifers were higher in reservoir stations, with mean values in the ponds approximately 50% lower than those of the reservoir. The microphagous species dominated during all the time, while the raptorial species were accidental in all studied environments. The ponds were represented by four significant indicator species: Brachionus caudatus, B. leydigi, Dicranophoroides caudatus and Testudinella patina and the reservoir by three: B. falcatus, B. havanaensis and Conochilus dossuarius. In general, nine species were significantly associated with some categories of environmental conditions, such as high or low turbidity and low values of conductivity and TDS. Four of the five best bioindicator species belonged to the microphagous genus Brachionus. B. havanaensis indicated five environmental conditions (IndVal > 93.1%), and it appeared to be a key species in this Neotropical semiarid reservoir influenced by aquaculture activities. The dominance of microphagous rotifers suggests a functional redundancy of species in the studied environments. We found that these systems and their management affected the planktonic rotifer community in this region of Brazil by increasing the species richness.

ABSTRACT. Abiotic variables and phytoplankton effects on zooplanktonic community from a reservoir in northeast Brazil. Zooplankton from Mundaú reservoir, State of Pernambuco, northeast Brazil was studied concerning temporal (hours and seasonal period) and spatial (pelagic and coastal regions in different depths) variabilities, correlating them to the environmental variables and the phytoplankton. Twenty-three infrageneric and five subgeneric zooplankton taxa were observed. On the whole, Rotifera was the dominant group during this study, especially influenced by the oxygen concentrations. Phytoplankton was dominated by Cyanobacteria. On the dry period, physical variables certainly controlled the zooplankton's development, allowing elevated algal densities. On the rainy period, zooplankton correlation with the system's nutrients levels on pelagic region probably conduced to a resources competition between phytoplankton and zooplankton, controlling algal densities.KEYWORDS. Dynamic, zooplanktonic community, reservoir, northeast Brazil. RESUMO.O zooplâncton do reservatório de Mundaú, Pernambuco, nordeste do Brasil foi estudado quanto a variabilidade temporal (entre os horários e períodos seco chuvoso) e espacial (nas regiões pelágica e litorânea em diferentes profundidades) correlacionando-as com as variáveis ambientais e com o fitoplâncton. Vinte e três táxons infragenéricos e cinco subgenéricos de zooplâncton foram encontrados. De forma geral, Rotifera foi o grupo dominante em todo o estudo. O fitoplâncton foi dominado pelas cianobactérias. No período seco, as variáveis físicas certamente controlaram o desenvolvimento do zooplâncton, favorecendo o estabelecimento de elevadas densidades algais. No período chuvoso, a correlação do zooplâncton com os níveis de nutrientes do sistema na região pelágica provavelmente conduziu a uma competição de recursos entre o fitoplâncton e o zooplâncton, controlando as densidades algais. PALAVRAS-CHAVE.Dinâmica, comunidade zooplanctônica, reservatório, nordeste do Brasil.