Longitudinal distribution of Copepoda populations in the transition zone of Paranapanema River and Jurumirim Reservoir (São Paulo, Brazil) and interchange with two lateral lakes.

Longitudinal changes in composition, abundance, and distribution of copepods were studied at the transition zone of Paranapanema River-Jurumirim Reservoir (SP, Brazil). The interchange of biotic material between marginal lakes and the river system was also examined. Water samples were obtained from 6 stations along a stretch of 13 km of the Paranapanema River, from an upstream reach with high water velocity up to the river mouth into Jurumirim Reservoir. Two other sites in lateral lakes were also sampled. Nine copepod taxa were identified: 3 calanoids (Argyrodiaptomus furcatus Sars, Notodiaptomus iheringi Wright, and N. conifer Sars) and 6 cyclopoids (Eucyclops Claus, Microcyclops Claus, Mesocyclops longisetus Thiébaud, Thermocyclops decipiens Fischer, T. minutus Lowndes, and Paracyclops Claus). Harpacticoids were also collected. Calanoid and cyclopoid nauplii and copepodids, and harpacticoids were the most abundant organisms. In general, there was a longitudinal decrease in copepod abundance, whereas an increase was detected near the lakes. The abundance of most copepods was inversely correlated with current velocity and suspended solids. Higher abundance was observed in the river main course during the rainy season, during which there is a higher connectivity between the lakes and the main river. This promotes exportation of biologic material from marginal lakes to the river system, a biotic exchange reflecting the importance of marginal lakes to the river community structure.

Metano entérico de bovinos leiteiros em condições tropicais brasileiras

The objective of this work was to quantify methane (CH4) emission using the sulfur hexafluoride (SF6) tracer technique, by dairy cattle on pasture in Brazilian tropical field conditions. Measurements were performed in the rainy season, with Holstein and Holstein x Zebu crossbred, from lactating and dry cows and heifers grazing fertilized Tobiatã grass, and heifers grazing unfertilized Brachiaria grass. Methane and SF6 concentrations were determined by gas chromatograph. Methane emissions by lactating cows varied from 13.8 to 16.8 g/hour, by dry cows from 11.6 to 12.3 g/hour, by heifers grazing fertilized grass was 9.5 g/hour and by heifers grazing unfertilized grass varied from 7.6 to 8.3 g/hour or 66 to 72 kg/head/year. Methane emission per digestive dry matter intake (DMDI) varied from 42 to 69 g/kg DMDI for lactating cows, 46 to 56 g/kg for dry cows, 45 to 58 g/kg for heifers grazing fertilized grass and 58 to 62 g/kg for heifers in unfertilized grass pasture. The CH4 emission measured on dairy cattle feeding tropical grasses was higher than that observed for temperate climate conditions.

Alien fishes in lakes of the Doce river basin (Brazil): Range, new occurrences and conservation of native communities

The present study shows the distribution of alien fish species in tropical lakes in the middle Doce river basin, southeastern Brazil, obtained from a rapid assessment program. The causes for their introductions were sport-fishing improvement in some specific lakes and aquaculture in the studied basin. Presently, these species have a wide distribution occurring in 41 of the 54 lakes studied, representing an actual threat to regional native fish community. The natural connection among lakes and streams during the rainy season and the dispersal mediated by local people are the main invasion agents for alien fishes. The success of these invaders is probably due to absence of pre-existing effective competitors or top-predators in the invaded communities. We consider that the eradication of alien fishes by means of the available management tools may be very difficult due to the large number of lakes invaded and to the wide spectrum of lake conditions and resources exploited by these alien species. We recommend the use of environmental education as a tool to stop the human-mediated dispersion of aliens and to improve conservation of native fish community in lakes where these alien species are not present yet. © 2004 Instituto de Ciências Biológicas - UFMG.

Visual signaling and reproductive biology in a nocturnal treefrog, genus Hyla (Anura: Hylidae)

We investigated reproductive activity, courtship behavior, call structure, body size, clutch size, oviposition site, and reproductive mode of Hyla sp. (aff. ehrhardti). Males called in all months, but showed a peak of activity during the rainy season. Three pair formations were observed and courtship involved stereotyped behavioral sequences, including visual signaling. Males emitted three different vocalization types: advertisement calls, courtship calls, and a vocalization of unknown function. Females attained larger body sizes than males and deposited an average of 74.5 unpigmented eggs per clutch. Early larval stages are aquatic but restricted to water in constructed subterranean nests; subsequent to flooding of nests, exotrophic tadpoles live in ponds or streams. Courtship behavior in Hyla sp. (aff. ehrhardti) is complex and the diverse repertoire of limb movements, exhibited by males, probably provide visual stimuli to females in this nocturnal treefrog. Hyla sp. (aff. ehrhardti) belongs to the H. albomarginata group. Considering the reproductive modes in this group, the complexes of H. albosignata and of H. albofrenata can be considered more close related to each other than to the H. albomarginata complex. © Koninklijke Brill NV, Leiden, 2004.

Effect of air humidity on the egg viability of predatory mites (Acari: Phytoseiidae, Stigmaeidae) common on rubber trees in Brazil

Rubber pest mites, Calacarus heveae and Tenuipalpus heveae, reach economic damage levels at the end of the rainy season and the beginning of the dry season in Brazil. Therefore, low humidity adaptation might be an important characteristic for predatory mites to successfully control pest organisms. This study determined the effect of the relative humidity (RH) levels of 30-100% on the hatching of larvae of Amblyseius acalyphus, Euseius citrifolius, Iphiseiodes zuluagai, Metaseiulus camelliae, Agistemus floridanus and Zetzellia malvinae at 25 ± 0.5°C. These predatory mites are common on rubber trees in the state of São Paulo and might be used for introduction in the major rubber tree production regions in the state of Mato Grosso. At 70% RH or higher, viability was 70% or higher for all species, indicating that their performance might be higher during the rainy season than during the dry season. Eggs of E. citrifolius and M. camelliae presented higher viability at the lower relative humidity levels than those of other species, indicating that these species might have higher chance to persist in the dry season. It is suggested that M. camelliae should be further evaluated for introduction in the state of Mato Grosso, considering that this mite is not yet present in that area. © Springer 2006.

Ecology and morphological characterization of gametophyte and 'Chantransia' stages of Sirodotia huillensis (Batrachospermales, Rhodophyta) from a stream in central Mexico

The morphology and phenology of Sirodotia huillensis was evaluated seasonally in a central Mexican first-order calcareous stream. Water temperature was constant (24-25°C) and pH circumneutral to alkaline (6.7-7.9), and calcium and sulfates were the dominant ions. The gametophyte stages were characterized by the presence of a distinctive mucilaginous layer, a marked difference in phycocyanin to phycoerythrin ratio between female and male plants, and the presence of a carpogonia with a large trichogyne (>60 μm). Occasionally three capogonia were observed on a single basal cell. The 'Chantransia' stages were morphologically similar to those described for the other members of Batrachospermales. A remarkable observation was the formation of dome-shaped structures, consisting of prostrate filaments that are related with the development of new gametophytes. Chromosome numbers were n = 4 for fascicle cells, cortical filament cells and dome-shaped cells, and 2n = 8 for gonimoblast filament cells and 'Chantransia' stage filaments. Gametophytes and 'Chantransia' stages occurred in fast current velocities (60-170 cm/s) and shaded (33.1-121 μmol photons/m2/s) stream segments. The population fluctuated throughout the study period in terms of percentage cover and frequency: the 'Chantransia' stages were most abundant in the rainy season, whereas gametophytic plants had the highest frequency values during the dry season. These results were most likely a result of fluctuations in rainfall and related changes in current velocity. Some characteristics of this population can be viewed as probable adaptations to high current velocities: the mucilaginous layer around plants that reduces drag; potential increase in fertilization by the elongate and plentiful trichogynes and abundant dome-shaped structures producing several gametophytes.

Urban and suburban malaria in Rondônia (Brazilian Western Amazon) II. Perennial transmissions with high anopheline densities are associated with human environmental changes

Longitudinal entomological surveys were performed in Vila Candelária and adjacent rural locality of Bate Estaca concomitantly with a clinical epidemiologic malaria survey. Vila Candelária is a riverside periurban neighborhood of Porto Velho, capital of the state of Rondônia in the Brazilian Amazon. High anopheline densities were found accompanying the peak of rainfall, as reported in rural areas of the region. Moreover, several minor peaks of anophelines were recorded between the end of the dry season and the beginning of the next rainy season. These secondary peaks were related to permanent anopheline breeding sites resulting from human activities. Malaria transmission is, therefore, observed all over the year. In Vila Candelária, the risk of malaria infection both indoors and outdoors was calculated as being 2 and 10/infecting bites per year per inhabitant respectively. Urban malaria in riverside areas was associated with two factors: (1) high prevalence of asymptomatic carriers in a stable human population and (2) high anopheline densities related to human environmental changes. This association is probably found in other Amazonian urban and suburban communities. The implementation of control measures should include environmental sanitation and better characterization of the role of asymptomatic carriers in malaria transmission.

Organização celular dos testículos em Hylidae e leptodactylidae, no Pantanal (Estado do Mato Grosso do Sul, Brasil)

The objective of this work was to make a comparative analysis of germ cell organization at different stages of cellular differentiation in adult males of Dendropsophus nanus (Boulenger, 1889), Pseudis limellum (Cope, 1862), P. paradoxa (Linnaeus, 1758), and Scinax acuminatus (Cope, 1862), belonging to the family Hylidae; and Leptodactylus chaquensis (Cei, 1950) and L. podicipinus (Cope, 1862), belonging to the family Leptodactylidae, collected in the Pantanal and in Serra da Bodoquena, Mato Grosso do Sul State, Brazil. The testes were removed and fixed, dehydrated in a graded series of ethanol and embedded in methacrylate glycol resin (Historesin Leica®). The sections were stained by 1% toluidine blue and observed under light microscope. It was detected that all individual of the Hylidae family show, throughout the year, the presence of all germ cell types of spermatogenesis. However, all Leptodactylidae family individuals only show the presence of all germ cell types during the rainy season. The variations of characteristics in seminiferous epithelium organization, as well as the evident difference in the amount of spermatozoa inside the tubules, are evidence that the anurans in this work show different forms of spermatogenesis development throughout the year: the cycle is continuous for the Hylidae family, and discontinuous with explosive release of spermatozoa for the Leptodactylidae family.

Foraging behavior and colony cycle of agelaia vicina (Hymenoptera: Vespidae; Epiponini)

The neotropical Agelaia vicina has the largest nest built among social wasps, yet little is known about nest construction, growth and structure. In this work, the development of two nests of A. vicina was followed. Studies were done through analysis of images to estimate the growth of nests. The material collected below the nests was examined to estimate colony productivity. Nests were collected to analyze their architecture and structure. Colony cycle was similar in the two colonies. Colonies increase in size throughout the dry season and into the rainy season, with a sudden drop in production at the end of the rainy season. The colonies doubled in size in about six months.

Efeito de três espécies de gramíneas forrageiras sobre a estrutura da pastagem e distribuição vertical de larvas infectantes de nematódeos gastrintestinais de ovinos

The knowledge of interaction between infective larvae setting and the type of grass is important to epidemiological studies and the control of gastrointestinal nematodes in sheep. The objective of this work was to evaluate the effects of three species of forage grasses on pasture characteristics and the vertical distribution of infective larvae (L3) of gastrointestinal nematodes of woolless sheep on the grasses during the rainy season. Sixty non-periparturients ewes were used, naturally infected, equally distributed on 2ha paddocks sowed with Tanzania, star, and gamba grasses, managed under continuous grazing system, from October 2003 to March 2004, at Santa Bárbara farm, Barreiras-Bahia-Brazil. Data of three samples between December 2003 and March 2004 were analyzed by SAS, using split-plot design, with 10 replications. Infective larvae of Haemonchus spp. and Trichostrongylus spp. were observed on forage in all stratus of vertical layer of the grasses without a defined pattern. Pastures with different characteristics under continuous grazing system had good conditions for developing infective larvae of sheep.

Qualidade microbiológica da água e histopatologia de brânquias de peixes provenientes de pisciculturas do município de itapecuru-mirim, Estado do Maranhão

The present study evaluated the microbiological water quality and tissue lesions in gills from Nile tilapia (Oreochromis niloticus) and hybrid tambacu (Colossoma macropomum female x Piaractus mesopotamicus male). For this, water and gills were collected from fish farming at six locations in Itapecuru- Mirim County, Maranhão State. Microbiological water analyses revealed contamination by total coliforms, Escherichia coli and heterotrophic bacteria. In the gills, we observed a diversity of Gram-positive and Gramnegative bacteria. The tissue lesions were: lamellar fusion, interlamellar hyperplasia, sub-epithelial edema and telangiectasia. Inflammatory lesions were not observed. Significant statistical difference (p > 0.05) was not detected when comparing different gills lesions during rainy and dry season. The correlation between lesion and pond type was statistically different (p < 0.05) for lamellar fusion and interlamellar hyperplasia which occurred more frequently at ground ponds. Regarding the frequency of lesions in the different fish species, there was statistical difference (p < 0.05), and the tambacu was more sensitive to lamellar fusion while tilapia was more sensitive for the other lesions. In relation to the sampling stations, there was statistical difference for all the gill lesions. In conclusion, tissue lesions are nonspecific and function as a defense mechanism against polluted aquatic environments, without infectious character.

Crescimento, comportamento ingestivo e desempenho reprodutivo de novilhas mestiças holandês x zebu, em pastejo, submetidas à suplementação protéica durante a época das águas

The objective of this study was to evaluate the effect of supplemental protein during the rainy season on body growth, ingestive behavior and reproductive performance of crossbred Gir x Holstein dairy heifers, with mean age of 21 ± 4.1 months and average initial body weight of 296.7 ± 57.3 kg, distributed in a completely randomized design with four treatments and six replicates per treatment. Heifers remained on Brachiaria brizantha cv. Marandu pasture, managed according to a rotational grazing system and, as treatment, it was supplemented with protein concentrate (34%, 43%, 56% and 66% BW) and level of supply of 0.30% body weight (BW). The animals were weighed and the mean weight of the lot was used for the calculation of adjustment of the amount of concentrate offered. Heifers that reached 330.0 kg of live weight were artificially inseminated and, 45 days after insemination, pregnancy diagnosis was performed for the calculation of pregnancy rate and age at conception. No significant difference of protein levels was observed on grazing, eating behavior, productive performance and age at conception of dairy heifers on pasture. The average daily weight gain of BW and age at conception were, on average, 0.907 kg/animal and 24.03 months, respectively.

Above- and below-ground biomass and carbon dynamics in Brazilian Cerrado wet grasslands

Questions: Grasslands are usually neglected as potential carbon stocks, partially due to the lack of studies on biomass and carbon dynamics in tropical grasslands. What is the importance of Brazilian tropical wet grasslands as carbon sinks? Does fire frequency and season affect biomass and carbon allocation in Brazilian wet grasslands? Location: Wet grasslands, tropical savanna, Jalapão, Tocantins, northern Brazil. Methods: We determined biomass above- and below-ground, estimated carbon stocks in biennially burned plots (B2) and plots excluded from fire for 4 yr (B4). Moreover, we determined biomass in both rainy and dry seasons. Samples were 0.25 m × 0.25 m × 0.2 m (eight samples per treatment, applying a nested design, total of 48 samples). The biomass was classified in above-ground graminoids, forbs and dead matter, and below-ground roots and other below-ground organs. We used ANOVA to compare variables between treatments and seasons. Results: More than 40% of the total biomass and carbon stocks were located below-ground, mostly in roots. A high proportion of dead biomass (B4) was found in the above-ground material, probably due to low decomposition rates and consequent accumulation over the years. Although these grasslands do not experience water stress, we found significant evidence of resource re-allocation from below-ground organs to the above-ground biomass in the rainy season. Conclusions: We found more dead biomass in the rainy season, probably due to low decomposition rates, which can increase fire risk in these grasslands during the following dry season. These tropical wet grasslands stored high amounts of carbon (621 to 716 g C.m-2), mostly in the roots. Thus, policymakers should consider tropical grasslands as potential carbon stocks, since they are one of the most threatened and unprotected ecosystems in Brazil. © 2012 International Association for Vegetation Science.

Biochemical biomarkers in Scinax fuscovarius tadpoles exposed to a commercial formulation of the pesticide fipronil

One of the main pesticides used in the cultivation of sugarcane in São Paulo State, Brazil, is Regent®800WG, the main active compound of which is fipronil. Fipronil is a potent insecticide that eliminates pests, including insects resistant to pyrethroids, organophosphates (OP) and carbamates (CA). There is little known on the toxic effects of fipronil on non-target organisms, such as tadpoles of frogs. It is possible that this compound carries a high toxicity for these organisms, since the pesticide can be incorporated into aquatic environments during the rainy season, a time which coincides with the time of amphibian reproduction and the occurrence of tadpoles in the aquatic environment in this region. Thus, the pesticide could be contributing to the decline of amphibians in the northwest region of São Paulo state due to its wide use. This study aimed to test the influence of Regent®800WG on some biochemical systems of tadpoles (such as antioxidant defense systems) at different stages of development. The results of analysis from in vivo exposures demonstrated that only a few parameters in the groups exposed to fipronil responded to exposure to Regent®800WG, results which indicate that the pesticide instigates biochemical responses in tadpoles. Although catalase and glucose-6-phosphate dehydrogenase (G6PDH) were unchanged during the experiments, glutathione-S-transferase (GST) was inhibited in tadpoles, and the activity of glutathione reductase (GR) varied according to the exposure period and pesticide concentration. This data demonstrated the influence of the fipronil formulation on the metabolism of tadpoles, and showed that it can increase their susceptibility to environmental contaminants. © 2013 Elsevier Ltd. All rights reserved.

Variação sazonal da comunidade protozooplanctônica em um ambiente oligotrófico tropical (reservatório de Ilha Solteira, Brasil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)