Navegando por Autor "Brandão, Luciana Pena Mello"

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    Current knowledge of South American cladoceran diapause: a brief review.
    (2016) Iglesias, Carlos; Bonecker, Cláudia Costa; Brandão, Luciana Pena Mello; Crispim, Maria Cristina; Sant'Anna, Eneida Maria Eskinazi; Gerhard, Miriam; Portinho, Jorge Laço; Barbosa, Paulina Maria Maia; Panarelli, Eliana; Santangelo, Jayme Magalhães
    The study of the structure and dynamics of cladoceran egg banks in SouthAmerica began only 15 years ago and the amount of knowledge, in addition to being scarce, is widely spread over partially national journals, theses, and books, and thus partially unavailable. We conducted a review of the literature published for this region, focusing mainly on the methodological approaches that have been applied and describe the main findings already published. The different methodological approaches make data comparability difficult. However, a total of 77 egg morphotypes were identified in the published studies. Among the variety of methods used, we suggest to adopt as the standard procedure: 1) pre isolation of eggs fromthe sediments by the “Sugar Flotation Method;'' 2) identification, enumeration, and sorting of egg morphotypes present in the sample; 3) individual hatching of each egg morphotype; 4) adult individual identification to the species level according to available keys; and 5) linking identified eggs to identified species’ adults.The absence of identification keys constitutesa challenge.Therefore, collaborative research with the aim of generating pictorial taxonomical support for Neotropical resting eggs are encouraged.Webelieve the adoption of the suggested protocol might facilitate this issue. An extremely low hatching success was reported for most studies and the factors triggering the break of dormancy in the resting eggs coming from permanent systems remain unknown. In conclusion, resting egg studies are a novel and promising field in South America, but with many challenges that need to be addressed.
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    Fluctuations of the population of Daphnia laevis Birge 1878 : a six-year study in a tropical lake.
    (2012) Brandão, Luciana Pena Mello; Sant'Anna, Eneida Maria Eskinazi; Brito, Sofia Luiza; Barbosa, Paulina Maria Maia
    The fluctuation of the population of Daphnia laevis in Lake Jacaré (Middle River Doce, Minas Gerais) was monitored monthly (at one point in the limnetic region) for six years (2002-2007) as part of the Program of Long-Term Ecological Research (LTER/UFMG). The following parameters were also monitored: water temperature, pH, electrical conductivity, dissolved oxygen, chlorophyll a, total phosphorus, phosphate, total nitrogen, nitrate, nitrite, ammonia, and densities of Chaoborus and ephippia of Daphnia laevis in the sediment. A seasonal pattern was observed in the fluctuation of D. laevis, with higher densities recorded during periods of circulation (May-August). A significant correlation was found between the density of D. laevis and temperature (r = –0.47, p = 0.0001), chlorophyll-a (r = –0.32, p = 0.016) and indicators of the lake’s trophic status (total phosphorus, r = 0.32, p = 0.007 and trophic state, r = 0.36, p = 0.003), as well as Chaoborus density (r = 0.43 and p = 0.002). These results indicate that changes in the physical and chemical characteristics of the water related with stratification and circulation of the lake may have a direct (temperature, total phosphorous) or an indirect (food availability, presence of predators, ephippia eclosion) influence on the fluctuation of the D. laevis population.