Knowledge of reproductive rates and life cycle of the Cladocera species is essential for population dynamic studies, secondary production and food webs, as well as the management and preservation of aquatic ecosystems. The present study aimed to understand the life cycle and growth of Alona iheringula Kotov & Sinev, 2004 (Crustacea, Anomopoda, Chydoridae), a Neotropical species, as well as its DNA barcoding, providing new information on the Aloninae taxonomy. The specimens were collected in the dammed portion of the Cabo Verde River (21°26′05″ S and 46°10′57″ W), in the Furnas Reservoir, Minas Gerais State, Brazil. Forty neonates were observed individually two or three times a day under controlled temperature (25±1°C), photoperiod (12 h light/12 h dark) and feeding (Pseudokirchneriella subcapitata at a concentration of 105 cells.mL−1 and a mixed suspension of yeast and fish feed in equal proportion). Individual body growth was measured daily under optical microscope using a micrometric grid and 40× magnification. The species had a mean size of 413(±29) µm, a maximum size of 510 µm and reached maturity at 3.24(±0.69) days of age. Mean fecundity was 2 eggs per female per brood and the mean number of eggs produced per female during the entire life cycle was 47.6(±6.3) eggs per female. The embryonic development time was 1.79(±0.23) days and the maximum longevity was 54 days. The species had eight instars throughout its life cycle and four instars between neonate and primipara stage. The present study using molecular data (a 461 bp smaller COI fragment) demonstrated a deep divergence in the Aloninae subfamily.

ABSTRACT. Richness estimators (Jackknife 1, Bootstrap, Chao 1 and ACE) were used to relate zooplankton species richness with amount of water collected per sample and number of samples throughout the year for the limnetic region of Sapucai River compartment of Furnas reservoir, state of Minas Gerais, Brazil. Seven 100 L samples were collected in sequence using a motor pump, and seven 70 L samples were collected in sequence using a plankton net (68 μm mesh size) in vertical hauls, to totalize 450 L, in three stations of the reservoir. Twelve monthly samplings were carried out over a year. The assessment of richness was made by analyzing the asymptotic behavior of the estimator curves. The samplings reached the asymptote from 350 L of collection with trawls and 400 L using a suction motor pump and reached the plateau on the 8th collection, which included both dry and rainy seasons. Regardless of the type of sampling, the volume of 400 L and eight sessions throughout the year is enough to register 90% of the zooplankton richness in the environment.

Aim This study seeks to analyze the vertical migration pattern of Cladocera species as related with the physical and chemical parameters of the water. Methods Samplings were carried out at 3-h intervals for 24 h in January 15 on the Sapucaí River compartment of Furnas reservoir, Minas Gerais State, Brazil. These samples were taken at five depths, from the surface to the near-bottom layer (0, 2, 4, 6, 8, and 9 m) totalizing 54 samplings for each limnological variable (temperature, pH, dissolved oxygen, electrical conductivity, chlorophyll-a content, Index of Trophic State, water transparency and Cladocera populations abundance). The samplings were performed at the limnetic region at a point with total depth of 9 meters. Results Water column thermal and chemical stratifications and thermocline occurrences were registered in the middle of the day. Among the 14 Cladocera species, only Ceriodaphnia cornuta and C. silvestrii displayed a significant migration pattern, which was mainly related to chlorophyll-a and dissolved oxygen concentrations. Diaphanosoma birgei and D. spinulosum are found at high densities near the surface and low ones in depth. The migration of Diaphanosoma was directly related to the concentration of chlorophyll a and pH, thus acting as a limiting factor. Feeding at high temperatures in the surface layer and assimilating at lower ones in depth, usually confer metabolic advantages to the vertically migratory species. Conclusions In this study, a well-defined pattern of vertical migration was found for two Cladocera species and its possible causes were hypothesized. To the species with less locomotory capacity, thermal and chemical stratifications can act as barriers to migration and distribution through the water column. This pattern may probably be found for zooplankton species in other compartments of Furnas reservoir, with similar physical and chemical properties.

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This study the life cycle and quantify the secondary production of the cladoceran Oxyurella ciliata under controlled conditions in a laboratory and use molecular biology as a tool to investigate its genetic characteristics. The organisms were collected from Baia do Gerente, a pond from the Pantanal region, MS state, Brazil. They were acclimatized, maintained at a controlled temperature (25 ± 1 °C) and photoperiod (12/12h light-dark), fed with the microalgae Raphidocelis subcapitata and observed daily to obtain the data. O. ciliata had a high total egg production of 34.18 ± 9.68 eggs/female and an average longevity of 58.50 ± 16.30 days. These values differed from those previously reported for O. longicaudis, another congeneric species. There was an exponential growth of biomass until instar 6 and the largest secondary production was from the young to the adult phase, which corresponds to the beginning of the reproductive phase. The molecular data revealed that the genetic divergence between the sequence of O. ciliata and that of O. longicaudis is approximately 18 %, which seems high considering that both belong to the same genus. Comparing life cycle data and DNA Barcode, Oxyurella ciliata and O. longicaudis are very distant and have distinct morphological and biological characteristics, such as: body size, egg size, growth, fertility, longevity and development times. This study highlights the importance of molecular studies and information on the life cycle of neotropical cladocerans, in an integrated way, to have a better taxonomic and ecological interpretation of the species.