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Temperature and light are acknowledged as important factors for hatching of resting eggs. The knowledge of how they affect hatching rates of this type of egg is important for the comprehension of the consequences of warming waters in recolonization of aquatic ecosystems dependent on dormant populations. This study aimed at comparing the infl uence of different temperature and light conditions on hatching rates of Daphnia ambigua and Daphnia laevis resting eggs from tropical environments. The ephippia were collected in the sediment of three aquatic ecosystems, in southeastern Brazil. For each lake, the resting eggs were exposed to temperatures of 20, 24, 28 and 32 °C, under light (12 h photoperiod) and dark conditions. The results showed that the absence of light and high temperatures have a negative infl uence on the hatching rates. Statistical differences for hatching rates were also found when comparing the studied ecosystems (ranging from 0.6 to 31%), indicating the importance of local environmental factors for diapause and maintenance of active populations.

The trematodes belonging to the genus Platynosomum are biliary parasites of birds and mammals (domestic and wildlife) in tropical and subtropical areas of the globe. Despite several reports on platynosomosis in captive nonhuman primates, mainly in South America, the taxonomy of species of Platynosomum that infect these hosts remains confused, and it is not clear whether the species found in cats is the same that infects nonhuman primates. Because a detailed morphological study of Platynosomum from nonhuman primates is lacking, in this study we analyzed specimens of Platynosomum recovered from the biliary system of Callithrix penicillata kept in captivity in an animal facility. The helminths were submitted to morphological and morphometric analyses in a light microscope and measurements of 16 morphological traits were taken. A kernel density estimation (KDE) was used to estimate density distributions of the measurements obtained as well as the occurrence of overlap with the ranges of the measurements known to 2 other species of Platynosomum previously described from South American marmosets, Platynosomum amazonensis and Platynosomum marmoseti. A principal component analysis (PCA) was also performed in order to evaluate the position of each of the 3 species in the multivariate gradient of morphometric measurements. The occurrence of a growth gradient was also evaluated by analysis of correlation between the measurements. Besides a great morphological variability, all specimens obtained from marmosets in this study were identified as Platynosomum illiciens (Braun, 1901). In addition, the published ranges of the measurements of P. amazonensis and P. marmoseti were completely contained within the ranges found in this study as revealed by KDE. The PCA did not show the formation of groups, and the 3 species were distributed along a growth continuum, also corroborated by correlation analysis. Therefore, P. amazonensis and P. marmoseti are here synonymized with P. illiciens. The involvement of wildlife hosts to the epidemiology of feline platynosomosis and implications for its control are briefly discussed.

(Copepoda, Rotifera, Cladocera and Protozoa: Amoeba Testacea) from natural lakes of the middle Rio Doce basin, Minas Gerais, Brazil.Abstract: A list of zooplankton species identified during ten years of studies in the lake system of the middle Rio Doce basin is presented. This lake system integrates the Atlantic Forest biome, a biodiversity hotspot. Three types of studies were achieved by the Brazilian Long Term Ecological Research Program (Brasil-LTER/PELD-UFMG site 4): i) a temporal study (study 1) which sampled four lakes monthly and three lakes twice a year during ten years; ii) a comparative study of limnetic and littoral species composition (study 2) and iii) a spatial study (study 3) that evaluated the species composition of eighteen lakes (eight lakes inside the Rio Doce State Park (RDSP) and ten lakes in its surrounding area) during one year with quarterly sampling. A total of 354 taxa were identified out of which 175 belong to the Rotifera, 95 to the Protozoa (Amoeba Testacea), 55 to Cladocera and 25 to Copepoda. Although many identified species where common in tropical environments, we present new records for the Middle Rio Doce basin. The group of lakes outside the RDSP showed higher exclusive species compared to lakes inside the RDSP. This pattern may be due to higher disturbance intensity and frequency to which the lakes outside RDSP are subjected, being an important factor affecting community structure. These aquatic ecosystems presents more than half of the zooplankton species registered for the Minas Gerais State and is, undoubtedly, one of the Brazil's priorities for conservation, sustaining high diversity in a very small, limited and threatened region. Resumo: Uma lista das espécies de zooplâncton identificadas durante dez anos de estudos no sistema de lagos do médio Rio Doce é apresentada. Este sistema de lagos faz parte do bioma da Mata Atlântica, um hotspot de biodiversidade. Três tipos de estudos foram conduzidos pelo Programa de Pesquisas Ecológicas de Longa Duração (PELD-UFMG site4): i) um estudo temporal, que amostrou quatro lagoas mensalmente e três lagoas semestralmente durante dez anos; ii) um estudo comparativo entre a composição de espécies da região limnética e litorânea e iii) um estudo espacial que avaliou a composição de espécies de dezoito lagoas (oito dentro dos limites do Parque Estadual do Rio Doce (PERD) e dez na sua região do entorno) durante um ano com amostragens trimestrais. Um total de 354 taxa foram identificados sendo 175 pertencentes a Rotifera, 95 a Protozoa (Amoeba Testacea), 55 a Cladocera e 25 a Copepoda. Embora muitas espécies identificadas sejam comuns a ambientes tropicais, são apresentados novos registros para a bacia do Médio Rio Doce. O grupo de lagos fora do PERD apresentou uma maior riqueza exclusiva comparado ao grupo de lagoas dentro do PERD. Este padrão pode ser devido a maiores frequência e intensidade de distúrbios aos quais as lagoas fora do PERD estão sujeitas, já que este é um fator importante que afeta a estruturação de comunidades. Este ecossi...

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Vertical gradients (e.g., water temperature and density) are a measurable expression of the potential energy of a water body, which is a fundamental driver for biogeochemical processes in aquatic ecosystems. Seasonal vertical stratification is typically described by the mixed layer and thermocline depths, and these metrics are often estimated through visual assessment of graphical plots or using numerical methods. The most widely used numerical method estimates the derivative of temperature (or density) along the depth, but it is sensitive both to profile data resolution and presence of nonconforming observations. In this study, we propose a new method of modeling vertical gradients using a four‐parameter sigmoidal function, including temporal autocorrelation. The parameters were estimated through Bayesian nonlinear regression with conditional autoregressive errors. The proposed method provides a quantitative and automated way to estimate the mixed layer and thermocline depths even for data profiles with a poor resolution. It also showed good performance against high‐frequency measurement data.

10Despite the increasing understanding about differences in carbon cycling between temperate and tropical freshwater systems, 11our knowledge on the importance of organic matter (OM) pools on light absorption properties in tropical lakes is very scarce. 12We performed a factorial mesocosm experiment in a tropical lake (Minas Gerais, Brazil) to evaluate the effects of increased 13 concentrations of allochthonous and autochthonous OM on the light absorption characteristics of colored dissolved organic 14 matter (CDOM), in addition to differences in light availability. We added inorganic nutrients (to stimulate OM 15 autochthonous production by phytoplankton growth) and allochthonous OM, and also introduced shading. Dissolved organic 16 carbon (DOC), Chl-a, nutrients, total suspended solid concentrations (TSM) and spectral CDOM absorption were measured 17 every three days to evaluate how they responded to these treatments. CDOM quality was characterized by spectral indices