RCAAP Repository

The aim of this research was to study the ciliated protozoa community at three sampling stations that receive different levels of domestic sewage along the São Pedro Stream in the municipality of Juiz de Fora, Minas Gerais, Brazil, in order to determine the influence of organic pollution on this community and to assess the feasibility of using ciliates as water quality indicators. Four physical-chemical parameters of the water samples were evaluated: dissolved oxygen concentration, electrical conductivity, pH and temperature. The sediment was obtained manually, using dredges with capacity of 300 mL, at each collection point. Point 1 was located in a rural region that receives a low sewage load, while Points 2 and 3 were located in populated regions receiving high sewage loads. We found 22 ciliate species, of which 18 are included in the saprobic system and are considered bioindicators. These showed beta-mesosaprobic environments at Point 1 and alfa-mesosaprobic to polisaprobic environments at Points 2 and 3. The low levels of dissolved oxygen and the high electrical conductivity values at Points 2 and 3, together with the strong similarity between the ciliate taxocenoses of these points and the weak similarity between Point 1 and the other two, confirm the high sewage loads received at the latter two points. The combination of the biological indicators and physical-chemical analyses therefore proved itself to be an efficient method of evaluating water quality, and has excellent potential to support decisions on the conservation of headwaters and recuperation of degraded environments in lotic systems.

The vertical distribution and the segregation by size of the yellow clam Mesodesma mactroides Deshayes, 1854 were investigated in the intertidal zone and its limits with the lower and upper shores at exposed sandy beaches of Rio Grande do Sul state, Brazil. The gathering was made throughout 12 months; from the Pinhal beach towards the south of the State, in six 15 km equidistant transects, determined through random selection. In these transects, the calculation of 30 consecutive waves was made in order to determine its average amplitude point (P0), from which two points were marked towards the lower shore (P-1 and P-2) and three towards the upper shore (P1, P2 and P3). A 30 by 50 cm cylinder was buried down to the depth of 40 cm, the material was separated with a 0.25 cm mesh and the specimens were quantified and measured in length. The yellow clam presented segregation by size, especially between recruit and adult individuals, with recruits occupying preferably the zones above P0 and adults from this point towards the sea. The young specimens are distributed through all zones, mixed with adult and recruit specimens, which dismisses the hypothesis of segregation by size in function of competition for space and food, once the burying depth is directly proportional to their length. However, the segregation between recruits and adults might be related to the filtering mechanism of the adults, which could ingest the larva, as well as the fact that the recruits, being small and light, are easily transported to the regions above P0. Seasonal migration was observed for adult individuals during winter and spring, probably associated to the reproduction period of the species, being that the peak of recruitment was greater in the end of the winter and the beginning of spring.

Atherinella blackburni is a silverside species whose occurrence on the Brazilian coast was not properly registered until recently. So far, records of its distribution along the Brazilian shore were limited to Itaparica Island, Bahia State, and Porto Inhaúma, Rio de Janeiro State. In a recent survey of the ichthyofauna of Itamambuca Beach, Ubatuba, São Paulo State, 100 specimens of this species were collected, yielding a considerable source of information regarding its ecology and a new southern limit of its distribution. A detailed survey of an ichthyological collection revealed lots of this species from regions of the Brazilian Northeast, resulting in a northward expansion of the occurrence of A. blackburni in Brazilian waters. Besides the populations found on the Brazilian coast, the species also occurs discontinuously in the Atlantic coasts of Costa Rica, Panama and Venezuela. Meristic and morphometric analysis showed overlapped values between Brazilian populations and the ones closer to the Caribbean. An ecological study of A. blackburni at Itamambuca Beach revealed that it is a predominantly diurnal species with preference for warm and salty waters, often occurring in sandy-bottom environments. It was more abundant in Summer and Winter, when individuals with smaller values of length and weight also occurred.

Prey size is an important factor in food consumption. In studies of feeding ecology, prey items are usually measured individually using calipers or ocular micrometers. Among amphibians and reptiles, there are species that feed on large numbers of small prey items (e.g. ants, termites). This high intake makes it difficult to estimate prey size consumed by these animals. We addressed this problem by developing and evaluating a procedure for subsampling the stomach contents of such predators in order to estimate prey size. Specifically, we developed a protocol based on a bootstrap procedure to obtain a subsample with a precision error of at the most 5%, with a confidence level of at least 95%. This guideline should reduce the sampling effort and facilitate future studies on the feeding habits of amphibians and reptiles, and also provide a means of obtaining precise estimates of prey size.

The purpose of this study was to characterize the diet of the fish Brycon opalinus (Characidae) seasonally and locally, allowing for the determination of its food items and trophic relations with the aquatic and terrestrial environments. The study area encompasses three rivers (Paraibuna, Ipiranga and Grande) in the basin of the Paraibuna, southeast Brazil. Twelve monthly collections were made from January to December 2004. The degree of stomachic repletion and of accumulated visceral fat was analyzed, as was the intestinal length in each class of total length. The frequency of occurrence and the degree of food preference (DFP) of the food items of Brycon opalinus were determined by separating the vegetal and animal items, autochthonous and allochthonous, by insect order and vegetal family consumed. The frequency of occurrence of items of animal origin was found to be equivalent to that of vegetal origin, thus characterizing the omnivorism of Brycon opalinus feeding.

Whether the functional structure of ecological communities is deterministic or historically contingent is still quite controversial. However, recent experimental tests did not find effects of species composition variation on trait convergence and therefore the environmental constraints should play the major role on community convergence into functional groups. Seasonal cerrados are characterized by a sharp seasonality, in which the water shortage defines the community functioning. Hyperseasonal cerrados experience additionally waterlogging in the rainy season. Here, we asked whether waterlogging modifies species convergences into life-forms in a hyperseasonal cerrado. We studied a hyperseasonal cerrado, comparing it with a nearby seasonal cerrado, never waterlogged, in Emas National Park, central Brazil. In each area, we sampled all vascular plants by placing 40 plots of 1 m² plots in four surveys. We analyzed the species convergences into life-forms in both cerrados using the Raunkiaer's life-form spectrum and the index of divergence from species to life-form diversity (IDD). The overall life-form spectra and IDDs were not different, indicating that waterlogging did not affect the composition of functional groups in the hyperseasonal cerrado. However, there was a seasonal variation in IDD values only in the hyperseasonal cerrado. As long as we did not find a seasonal variation in life-form diversity, the seasonal variation of convergence into life-forms in the hyperseasonal cerrado was a consequence of the seasonal variation of species diversity. Because of high functional redundancy of cerrado plants, waterlogging promoted a floristic replacement without major changes in functional groups. Thus, waterlogging in the hyperseasonal cerrado promoted seasonal changes in species convergence into life-forms by reducing species diversity.

Food availability may affect metal toxicity for aquatic organisms. In the present study, the influence of high, medium and low densities of the algae Pseudokirchneriella subcapitata (10(6), 10(5) and 10(4) cells.mL-1, respectively) on the chronic toxicity of chromium to the cladoceran Ceriodaphnia dubia was investigated. C. dubia was exposed to a range of chromium concentration from 2.71 to 34.04 µg.L-1 and fed with algae at various densities. In another experiment, the green alga was exposed to chromium concentrations (94 to 774 µg.L-1) and supplied as food in different densities to zooplankton. The survival and reproduction of the cladoceran were measured in these toxicity tests. The IC50 for Cr to P. subcapitata and metal accumulated by algal cells were determined. The results of a bifactorial analysis (metal versus algal densities) showed that metal toxicity to zooplankton was dependent on algal densities. Significant toxic effects on the reproduction and survival of C. dubia were observed at 8.73, 18.22 and 34.04 µg.L-1 Cr when the test organisms were fed with 10(6) cells.mL-1 of P. subcapitata. Although the chlorophyta retain low chromium content, a decrease in the reproduction and survival of C. dubia occurred when they were fed with high algal density contaminated with 774 µg.L-1 Cr. It was concluded that high algal density have an appreciable influence on chromium toxicity to daphnids.

Measurements of ammonium and phosphate excretion by the Chironomus larvae were conducted in order to evaluate the importance of these chironomids for the internal loads of a small eutrophic urban reservoir. Ammonium and phosphate excretion rates by Chironomus larvae of small size (6-10 mm total length) were significantly higher than those of the Chironomids having medium (9-11 mm) and large (11-16 mm) sizes. A dependence in relation to temperature was recorded for the ammonium and phosphate excretions that was significantly higher at 25 °C than at 20 and 15 °C. Through a linear relation between biomass (dry weight) and total length and, between excretion and biomass and, data on chironomids densities, after an intense sampling in 33 sites distributed all along the reservoir bottom, the mean phosphate and ammonium excretion rates corresponded to 2,014 ± 5,134 µg.m-2/day and 1,643 ± 3,974 µg.m-2/day, respectively. Considering the mean biomass (34 mg.m-2) of Chironomus, the lake area (88,156 m²) and the mean excretion rates, the contribution of benthic chironomids to the internal loads would be 181 KgP and 147 KgN. for the sampling months (October-November 1998). These values showed that the internal loads by excretion from Chironomus larvae correspond to approximately 33% of the external loads of phosphorus in the lake and, in the case of nitrogen, to only 5%.

The elasmobranchs constitute an important resource in Argentinian fishing and they show reproductive characteristics that make them susceptible to the pressure of fishing. In spite of the importance of the resource our knowledge about the species of the Southwestern Atlantic is scarce. In this work we study the microanatomy of the oviduct and the oviducal gland of Sympterygia acuta. The results show a very folded oviduct with mucous and ciliated cells. The oviducal gland depicts the same zonation as other batoids, showing the typical four regions (club, papillary, baffle and terminal). The epithelium lining the glandular lumen is simple columnar with ciliated and glandular cells. The four zones show simple or ramified tubular gland the secretions of which constitute the egg's envelopes. The club and baffle zones are similar to those present in other species. The papillary one depicts a different pattern of secretions that other Rajiformes and the last zone of the gland is characterized by mixed adenomers. The information here exposed constitutes the first report on the microanatomy of the genital tract of S. acuta.

The influence of population density on some aspects of the reproductive biology of the snail Bradybaena similaris was studied. Molluscs were maintained under 0.2 (isolated), 0.3, 0.6, 1.0, 1.3 and 1.7 snail/m² densities. The animals maintained under 0.3 and 0.6 snail/m² showed the lowest numbers of eggs laid/snail, being the highest value observed to the 1.7 snail/m². The hatching of the snails maintained under 0.3 snail/m² density, begun at the 21st day after laying, and the maximum time required to the hatching was 36 days was observed to the eggs came from snails maintained under the densities 0.6, 1.0, 1.3 snail/m², respectively. The highest percentage hatchability (55.56%) was observed to isolated snails. The galactogen content in the albumen gland did not seem to accompany the alterations occurred in the reproduction of B. similaris in response to the different population densities.

Qualitative parameters of piapara semen (Leporinus elongatus) were evaluated before and after hormonal induction with carp pituitary extract at 2.5 mg.kg-1 of live weight. The progressive motility, the spermatic vigor and the lifetime of the spermatozoa were higher before the hormonal induction (P > 0.05). The percentage of normal spermatozoa and spermatozoa with secondary pathologies did not differ (P > 0.05) between treatments: before induction (44.0 and 44.4%, respectively) and after-induction (44.3 and 46.7%, respectively). However, the percentage of primary pathologies was higher (P < 0.05) for the semen collected before induction than for the semen collected after induction; the estimates were 12.2 and 8.0%, respectively. The most frequent pathologies were the taillessness with the frequencies of 27.4 and 36.3% followed by the headlessness for which the estimates were 10.1 and 3.9%, before and after induction respectively. The semen collected before the hormonal induction presented better qualitative parameters.

Hydras, the most representative freshwater Cnidaria, are of common occurrence in bodies of water in every continent except Antarctica. This study was planned with the aim of maintaining a population of Hydra viridissima in laboratory culture to enable the determination of the individual and population growth-rates of this species, as well as its population doubling time and generation time, with a view to employing these common animals as test-organisms in ecotoxicological assays. The organisms were maintained in reconstituted water at 20 ± 2 °C, illuminated at 800 lux with a photoperiod of 12 hours light: 12 hours dark, and were fed on neonates of the cladoceran Ceriodaphnia silvestrii (3 or 4 neonates per hydra, 3 times a week). The individual growth-rate (k) of the species was 0.43, the maximum length of the column 2.53 mm and the generation time 6.6 ± 1.5 days on average. The hydra population showed an intrinsic growth-rate (r) of 0.0468, according to the fitted curve, and a doubling time of 14.8 ± 2.63 days. Hydra viridissima is easy to grow in the laboratory and performs well in the conditions used in this study. It is thus a promising candidate test-organism for ecotoxicological studies.

The Saint Peter and Saint Paul Archipelago in the central tropical Atlantic, is an important ground of whale sharks that are commonly sighted throughout the year close to the fishing boats in the adjacencies of the islands. In sightings reported between February 2000 and November 2005, the lengths of the individuals ranged between 1.8 to 14.0 m. The causes of these concentrations in the archipelago are still unclear, once there are no upwellings and plankton concentrations for feeding, and no reproductive activities were reported. Nevertheless, they could be associated to the spawning period of the abundant flying fishes, mainly in the first semester, when sightings were more frequent.

The Restinga Antwren (Formicivora littoralis) has a narrow distribution range in southeastern Brazil, and it is a typical species of restinga habitat (sandy coastal plain vegetation). In this paper, we describe two new records for the species (22° 51' 45" S and 42° 14' 13" W; 22° 51' 14" S and 42° 11' 47" W) in the northern margin of the Araruama Lagoon, which represent a new inland limit for its distribution (11 km), besides assessing the current state of its habitat. We recorded supposed isolated subpopulations, most of them due the accelerated human-made fragmentation. The Massambaba Environmental Protection Area comprises the larger continuous extent of the suitable habitat for the Restinga Antwren, being essential to its long-term existence. However, the region lacks effective protected areas and, besides urgent practical measures, we recommend an accurate mapping and populational studies on this species.

We carried out a seed germination experiment using two thrush species in captivity. We compared the number of germinated seeds and germination time of control seeds (manually removed from fruits) and ingested seeds of Miconia prasina by two bird species, Turdus albicollis and T. amaurochalinus, and also compared retention times of seeds by both thrush species. Control seeds germinated more frequently than those ingested for one species, T. albicollis. The germination time of ingested seeds by T. amaurochalinus was similar to the control seeds but seeds ingested by T. albicollis took longer to germinate than the controls. Both thrush species had a similar seed defecation pattern. The cumulative number of defecated seeds increased by 2 hours after fruit ingestion. At the end of the first 30 minutes both species had already defecated approximately 50% of the seeds ingested Our results suggest that both species could act as disperser agents of M. prasina.

Leptodactylus labyrinthicus tadpoles reach a large size in the nest through consumption of trophic eggs. We previously suggested that the trophic eggs are laid just after amplexus has finished, but our new data do not support this hypothesis. We also present further details on the natural history of the species with regard to breeding activity, spawning site, retreats and the ability of tadpoles in preying upon fully-growth heterospecific tadpoles. We also show that the tadpoles are mainly nocturnal and take diurnal refuges. We collected the data in Brazil in three localities within the Cerrado Biome. We examined burrows used by L. labyrinthicus males, verified if females still contained mature eggs just after released from amplexus, and tested the ability of tadpoles in preying fully-growth heterospecific tadpoles. Field observations and experiments were conducted on tadpole activity time, hiding behaviour and level of susceptibility to predation by the bird leaf-scrapers in four sheltering situations. Reproduction could start before the first rains; this may be advantageous by allowing the tadpoles to exploit eggs of other frogs. We found one floating nest built in a temporary pool. The nest of the species is normally circumscribed in an excavated basin beside the water body. Adult males were found during the day with their head-out of the entrance of underwater burrows, which were perforations through dense root mats beside calling/spawning sites. Probably, these burrows in permanently water-filled soil are actively excavated by males. Females released all their eggs during the amplexus, so trophic eggs are not produced by the currently-accepted mechanism. Fully-grown heterospecific tadpoles were not preyed upon by L. labyrinthicus tadpoles, which can prey only slow-moving newly hatched ones. Field tadpoles took shelter under mud/dead leaves during daylight and became exposed on the bottom at night. Free-ranging leaf-scrapers removed dead leaves from a pool with their beaks and preyed upon tadpoles. In the experiments, the tadpoles sheltered under gravel/leaves during daylight, but they were exposed at night. Leaf-scrapers ate all exposed tadpoles, but no tadpole of the gravel/leaves trays was consumed. Hence the nocturnal habits and use of diurnal refuges may protect the tadpoles from visual predators, such as the leaf-scrapers.

Flavobacterium columnare is the causative agent of columnaris disease in freshwater fish, implicated in skin and gill disease, often causing high mortality. The aim of this study was the isolation and characterization of Flavobacterium columnare in tropical fish in Brazil. Piracanjuba (Brycon orbignyanus), pacu (Piaractus mesopotamicus), tambaqui (Colossoma macropomum) and cascudo (Hypostomus plecostomus) were examined for external lesions showing signs of colunmaris disease such as greyish white spots, especially on the head, dorsal part and caudal fin of the fish. The sampling comprised 50 samples representing four different fish species selected for study. Samples for culture were obtained by skin and kidney scrapes with a sterile cotton swabs of columnaris disease fish and streaked onto Carlson and Pacha (1968) artificial culture medium (broth and solid) which were used for isolation. The strains in the liquid medium were Gram negative, long, filamentous, exhibited flexing movements (gliding motility), contained a large number of long slender bacteria and gathered into ‘columns'. Strains on the agar produced yellow-pale colonies, rather small, flat that had rhizoid edges. A total of four Flavobacterium columnare were isolated: 01 Brycon orbignyanus strain, 01 Piaractus mesopotamicus strain, 01 Colossoma macropomum strain, and 01 Hypostomus plecostomus strain. Biochemical characterization, with its absorption of Congo red dye, production of flexirubin-type pigments, H2S production and reduction of nitrates proved that the isolate could be classified as Flavobacterium columnare.

The genus Anicla Grote, 1874 is composed of eleven species; their larvae are harmful, mainly to native and cultivated grasses, but up to now, there is information available of only two species. This study aims at detailing the bionomy of A. mahalpa Schaus; the data were obtained from a laboratory rearing under the following settings: 20 ± 2 ºC, 70 ± 10% relative humidity and 12 hours of photoperiod. Larvae were fed on ryegrass, Lolium multiflorum Lam. (Poaceae). The results expressed by the mean and respective standard error for the periods of each phase, in days, were the following: egg 6.00 ± 0.00, larva 36.47 ± 0.44, pre-pupa 5.23 ± 0.21, pupa 23.60 ± 0.37, and adult: longevity 15.24 ± 0.75 with pre-egg-laying-periods of 5.29 ± 0.32; egg-laying period, 9.64 ± 0.81, and post-egg-laying period, 0.71 ± 0.27 days. The mean number of egg-laying cycles per female was 7.36 ± 0.20 and 2,014.21 ± 78.93 eggs per female. Eggs, which are subspheric, have a diameter of 0.76 ± 0.01 mm; larvae passed through six instars; their head capsules width, provided a mean ratio of growth of 1.482. Pupae presented a mean width and length of 6.07 ± 0.06 and 17.24 ± 0.19 mm, respectively and weight of 0.33 ± 0.01 g.

The aim of this work was to observe and describe the feeding habits and available food resources of the swallow-tailed hummingbird, Eupetomena macroura. The study was carried out in a municipal park located in the city of Taubaté, in the state of São Paulo. The observations took place between December 2003 and October 2004, recording the following variables: 1) the plant species visited for feeding and territorial defense; 2) the kinds of food resources; and 3) the kinds of flight to procure and obtain food. E. macroura visited 12 plant species. For territorial defense, Mangifera indica was the most visited, whereas Malvaviscus arboreus was most visited for feeding. The foliage was the plant part that received the most frequent visits. In order to obtain nectar, the only species visited was M. arboreus; to obtain arthropods, the species most visited were Mangifera indica and Hymenaea stilbocarpa. In the dry season, the hummingbirds visited flowers, whereas in the rainy season they visited leaves to acquire food. The arthropod groups most frequently found on leafy branches were Homoptera and Psocoptera. Finally, the results of the type of flight analysis showed that flight used to capture food was more often observed than were flights to search for food. In conclusion, these observations suggest that E. macroura shows plasticity in feeding behavior, which can help it to persist in urban areas.

Pentastomids can infect the respiratory tract of lizards, causing their death and as a result influencing the population size of hosts. Despite this, studies on rates of pulmonary infection of Brazilian lizards, including those living in Caatinga ecosystems of northeastern Brazil are scarce. Active collections of lizards were performed from October to December 2004 in an area of Caatinga of the Estação Experimental de São João do Cariri - EESJC (07º 25' S and 36º 30' W), located in the state of Paraíba, Northeast of Brazil. Forty-five lizards inhabiting granite outcrops in an area of Caatinga were captured, belonging to the following species: Tropidurus hispidus (Spix, 1825) (18 individuals), T. semitaeniatus (Spix, 1825) (15 individuals), Phyllopezus periosus Rodrigues, 1986 (6 individuals), and P. pollicaris (Spix, 1825) (6 individuals). Laboratory examination revealed that all species had some degree of pulmonary infection caused by Raillietiella mottae. The highest rates of prevalence (66.7%) and mean intensity of infection (5.25 ± 2.01, range of 2-11) were observed in P. periosus. The results obtained in this study show that lizards of the Brazilian semi-arid region are infected by a generalist species of pentastomid. The most likely cause for such pattern is the similarity in lizards' diets (ants and termites). It is particularly noteworthy that T. semitaeniatus, P. periosus, and P. pollicaris represent new host records for R. mottae.