Repositório RCAAP

Studies on the longitudinal processes in reservoirs, involving physical, chemical and biological processes have been thoroughly appraised, suggesting the existence of a longitudinal organization controlled by the entrance and circulation of water which inserts modifications in the structuring of the system. To evaluate this effect, the Salto Grande reservoir (Americana, SP) was analyzed in 11 sampling stations in its longitudinal axis, in the rainy and dry seasons of 1997 considering the physical chemical and biological variables. Analyzing the results in agreement with the declining concentration degree of the river--barrage direction, a more significant correlation was verified in the dry period for total phosphorus (r² = 0.86), dissolved total phosphate (r² = 0.83), nitrite (r² = 0.93), inorganic phosphate (r² = 0.89), ammonium (r² = 0.84) and suspended material (r² = 0.85). In the rainy period, only nitrite (r² = 0.90) and conductivity (r² = 0.89) presented correlation with the distance of the dam, which demonstrates the effects of precipitation and the operational mechanism of the dam, as well as the distinction among the physical (sedimentation), chemical (oxidation) and biological (decomposition) processes in spatial heterogeneity of the system. These factors were decisive in the organization of these communities, with higher occurrence of rotifers and copepods in relation to cladocerans, the first ones being more abundant in the entrance of the Atibaia river, decreasing towards the dam direction, while copepods presented an inverse pattern. A distribution pattern similar to Copepoda was also verified for the Cladocera, evidencing a tendency to increase the density of organisms in the stations distant to the entrance of the Atibaia river, not being registered, however, a distribution gradient in the longitudinal axis, as observed for rotifers and copepods. In relation to the trophic degree a longitudinal gradient was also verified from eutrophic to oligotrophic depending on the location of the sampling station in relation to the longitudinal axis and period of analysis. The differences obtained, relating to the distribution of the environmental variables, demonstrate a characteristic pattern for reservoirs, with a longitudinal gradient in the sense river--barrage that inserts changes in the physical and chemical composition of the water, contributing to the differentiated establishing of biological communities.

A selection of exopolysaccharide (EPS) -- producing bacterial strains was conducted in groundwater adjacent to an old controlled landfill in the City of São Carlos (São Paulo, Brazil). The strains were isolated in P and E media under aerobic and microaerophilic conditions at 25ºC. A total of 26 strains were isolated and based on the mucoid mode of the colonies, 6 were selected and their morphological, physiological and biochemical aspects were characterized. All strains presented pigmentation, ranging from yellow to orange and from pink to salmon, with a shiny glistening aspect in all tested media. Strains Lb, Lc and Lg, which excelled the others with regard to the mucoid mode of the colonies, were selected to be cultured in E medium with alternate sucrose and glucose as carbon sources in anaerobiosis at 25ºC to analyze the production of EPS. Strains Lc and Lg were classified as being of order Actinomycelates, suborder Corynebacterineae. Lg strain was identified as Gordonia polyisoprenivorans and Lc strain did not correspond to a known description and therefore a more detailed study is under preparation. Considering all ecological aspects and the metabolic potential associated with the microorganisms of the environment studied, as well as the capacity to produce pigment and EPS, and the presence of G. polyisoprenivorans, a rubber degrader bacterium, the potential of the groundwater analyzed is evident as a source of microorganisms to be utilized in studies related to environmental remediation.

Vochysia elliptica (Vochysiaceae) is a shrubby plant, which does not have EFNs. Camponotus ants thieve nectar, and can decrease plant fitness by making flowers less attractive to pollinators. However, ants remove herbivores, wich can be beneficial. Results show that plants from which ants were excluded had lower rates of termite (simulated herbivore) removal than did plants visited by ants. Plants accessible to ants showed higher rates of termite removal in the base of leaves and in the inflorescence, than in the tip of leaves. This occurs because ants must pass through the principal axis to reach the inflorescence. Conclusive results of this cost/benefit analysis of the Camponotus sp. presence for V. elliptica can be obtained, with experimental manipulations.

The State Park of Ilha Grande is only a part (5,594 hectares) of the entire island (19,300 hectares) which is located off the south coast of Rio de Janeiro state, between the cities of Mangaratiba and Angra dos Reis. Approximately half of the Park area (47%) is covered by dense Atlantic forest. The secondary forest growth is in a process of ecological succession close to attaining maturity (43%) and the remaining part (10%) is composed of human-altered areas (1%), rocky outcrops with herbaceous vegetation (7%), mangroves and beaches (2%). The fauna is well represented but already shows signs of degradation with introduced species. The analysis of the degree of threat has shown that the dense forest habitat has a relatively stable status of conservation while the secondary forest, the mangrove and the herbaceous vegetation on rocky outcrops (and their fauna) are categorized as vulnerable. The area altered by human occupation is considered threatened. Since the coastal area where Ilha Grande is located is well known for its beautiful scenery (known as the green coast, because of the contrast between the ocean and the Atlantic forest covering the Serra do Mar mountain chain). There is a strong possibility for tourism to become the means in which to achieve economic sustainability for conservation. Contradictorily, tourism is also the major threat to local biodiversity and its landscape units. Because tourism is not organized and controlled, during high season the numbers grow above local capacity, giving rise to a proliferation of hotels, guesthouses and camping grounds. The resulting untreated open sewage, random garbage disposal and other harmful activities form the major threats to biodiversity.

International organizations and biodiversity scientists recognize three levels of biodiversity: genetic, species, and ecosystem. However, most studies with the goal of assessing biodiversity collect data at only a single level -- that of the species. Even when multiple levels of biodiversity are considered, usually only ecosystem diversity is also evaluated. Genetic diversity is virtually never considered. Yet, genetic diversity is essential for the maintenance of populations and species over ecological and evolutionary time periods. Moreover, because components of genetic diversity are independent of either species or ecosystem diversity, genetic diversity can provide a unique measure by which to assess the value of regions for conservation. Regions can be valuable for conservation of their genetic resources regardless of their levels of species or ecosystem uniqueness or diversity. In general, the same methods and statistical programs that are used to answer questions about population genetics and phylogenetics are applicable to conservation genetics. Thus, numerous genetic techniques, laboratory methods, and statistical programs are available for assessing regional levels of genetic diversity for conservation considerations. Here, we provide the rationale, techniques available, field and laboratory protocols, and statistical programs that can be used to estimate the magnitude and type of genetic diversity in regions. We also provide information on how to obtain commonly utilized statistical programs and the type of analyses that they include. The guide that we present here can be used to conduct investigations of the genetic diversity of regions under consideration for conservation of their natural resources.

In this paper the spatial distribution of Plecoptera nymphs in the Almas' River basin, Pirenópolis, GO, was studied. Two Surber samples, each comprising 20 sampling units and totalling 2 m², were taken in each of the 13 stations, one during the rainy season (January 1994) and the second during the dry season (July 1994). In 5 of these stations, monthly samplings were made from June 1993 to July 1994; in these, temperature, velocity, discharge, electrical conductivity and pH were measured. Regional rainfall was also obtained. To ascertain the distribution of nymphs in the habitat, a separate sample was taken. Of the factors considered, the most important affecting the spatial distribution of the stonefly nymphs were altitude, stream order, and anthropic influence. Locally, the genera Anacroneuria and Kempnyia showed clumped distributions, but the data for Gripopteryx and Tupiperla were inconclusive due to low numbers.

We studied the ectoparasite and the Amblyopinini beetle fauna associated with four small mammal species of the Atlantic Rainforest of Ilha Grande, an island located off the southern Rio de Janeiro State Coast, Southeastern Brazil, analyzing to what extent the parasites were specific to each region of the host body. During the study, a total of 90 individual rodents were captured: 61 Proechimys iheringi Thomas, 1911 (Echymyidae), 22 Sciurus aestuans (Thomas, 1901) (Sciuridae), 4 Oxymycterus sp. (Waterhouse, 1837), and 2 Nectomys squamipes (Brants, 1827) (Sigmodontinae). The data showed that the ectoparasites and Amblyopinini on some rodent hosts in Ilha Grande tend to prefer particular host body sites, and that some ectoparasite species sites may overlap owing to their inaccessibility to the host.

The effect of seed mass on germination and growth was tested in fresh-seeds of Blutaparon portulacoides, Panicum racemosum, and Spartina ciliata, selected at random in southern Brazilian populations. The seed mass varied within a population of the three species. Both B. portulacoides and P. racemosum showed normal frequency distribution of seed mass, while S. ciliata did not. Significant differences were observed in seed germination between large and small seeds of all species. In all species the capacity of seedling elongation was greater in seedlings of large seeds than those of small ones. Relative growth rate of seedlings of P. racemosum and S. ciliata decreased with time in all seed mass size-classes. On the other hand, the relative growth rate of B. portulacoides seedlings increased during the first 40 days. Seed mass is an important biological factor, affecting seed germination, seedling elongation, and growth of these species, and favoring large seeds, specially in areas of active sand accretion like coastal dunes.

Rapoport effect predicts that species geographic range sizes will increase toward higher latitudes, probably reflecting adaptations to extreme climatic conditions that increase species tolerance. Recently, studies about spatial patterns in species richness and geographic range size may be associated with the geometry of species' ranges. In this context, null models can be used to search for the causal mechanisms associated with these patterns. In this paper, we analyzed Rapoport effect using a null model to evaluate how phylogenetic structure and geometric constraints simultaneously affect latitudinal extents of 40 species of South American terrestrial Carnivora. The latitudinal extents of Carnivora tended to decrease toward Southern latitudes, in the opposite direction expected under a simple Rapoport effect, but in accordance to geometric expectations of position of midpoints in the continent. Using 5000 simulations, it was possible to show that the null regression coefficients of latitudinal extents against midpoints are positively biased, reflecting the geometric constraints in the latitudinal extents. The results were equivalent in phylogenetic and non-phylogenetic analyses. The observed regression coefficient was significantly smaller (line is less inclined) than expected by chance alone, demonstrating that the geometric constraints in the latitudinal extents exist even after controlling for phylogenetic structure in data using eigenvector regressions. This suggests that the "spirit" of Rapoport effect (sensu Lyons & Willig, 1997) could be maintained, i.e., that latitudinal extents in Southern region of the continent are relatively larger than those in Northern regions, even after controlling for phylogenetic effects.

The aim of this study was to assess the major food items ingested by adult specimens of Daphnia laevis within the eutrophic Pampulha reservoir in Belo Horizonte, Minas Gerais, Brazil. The gut content was analyzed after addition of sodium hypochlorite and also through the examination of dissected guts under scanning electron microscopy. The results showed that Chlorophyceae was the main food item ingested, representing c. 80.5% of the total ingested food. Moreover, Eutetramorus fottii, Coelastrum pseudomicroporum and Oocystis lacustris, the dominant phytoplankton species within the reservoir, were the most frequent cells found in the gut contents. Euglenophyta also represented an important food item accounting for 15% of the ingested material, including mainly Trachelomonas volvocina and Euglena oxyuris, although less abundant in the reservoir (< 10% of total phytoplankton). Blue-green algae occurred at much lower percentages in the guts than in the phytoplankton. A small amount of undigested Microcystis aeruginosa colonies were also found in the gut content of D. laevis. Scanning electron microscopy results showed that, besides phytoplankton cells, a great amount of abiogenic material was also ingested. The amount of this inorganic material increased considerably in the tract (from 15% to 75% of the gut content), when a peak of D. laevis was observed in the reservoir. Our assumption is that the ingestion of this inorganic material can be a strategy used by D. laevis to obtain additional food supply.

Rhipidocotyle pentagonum (Ozaki, 1924) is reported for the first time in South America parasitizing Auxis thazard and in a new host Katsuwonus pelamis. Tergestia laticollis (Rudolphi, 1819) is reported for the first time in South America and in Thunnus albacares, representing a new host record. Copiatestes filiferus (Leuckart, in Sars, 1885) is recorded for the first time in Brazil and in Thunnus albacares, another new host record. Tetrochetus coryphaenae (Yamaguti, 1934) is presented for the first time in Brazil parasitizing Thunnus albacares.

Two species of Digenea were recorded for the first time in South America and in new hosts: Acanthostomum spiniceps (Looss, 1896) (Cryptogonimidae) was reported from Astroscopus sexspinosus (Steindachner, 1877) (Uranoscopidae) and Diplomonorchis sphaerovarium Nahhas &amp; Cable, 1964 (Monorchiidae) from Ophichthus gomesi (Castelnau, 1855) (Ophichthidae). From the latter, Heliconema heliconema Travassos, 1919 (Nematoda, Physalopteridae), was also recovered representing also a new host for this nematode species.

This paper deals with variations in biomass and in the production of Eichhornia crassipes (water hyacinth) in a eutrophic tropical reservoir. Net production was assessed by both a traditional method and a demographic approach. The initial biomass ranges from 96 g DW.m-2 to a maximum of 2027 g DW.m-2. Net production estimates varied greatly according to which method was used to calculate them (traditional: 20.6 ton DW.hectare-1.year-1, demographic: 226.9 ton DW.year-1).

Fecal masses recently excreted and/or almost dry were collected weekly in a pasture of Brachiaria decumbens Stapf, from May 1990 to April 1992. The feces were conditioned in 15-liter opaque plastic buckets, containing lateral and top openings, where flasks were fastened for capturing Histeridae beetles present in these masses. Three thousand two hundred ninety-nine specimens were collected belonging to 11 species in the Genus: Phelister, Hister, Euspilotus, Acritus, and Xerosaprinus. The most frequent, constant, and abundant species were Phelister sp. nr. carinifrons and P. haemorrhous.

The stingless bee Melipona quinquefasciata is not included among the nine bee species of Melipona described in literature of NE Brazil. However, reports of some farmers raised suspicion on the occurrence of M. quinquefasciata in the state of Ceará, in NE Brazil. Investigations were carried out from July 1997 to September 2000, by means of trips to the areas of probable occurrence of this bee species. Results confirmed the presence of M. quinquefasciata in Ceará and determined its habitat along the chapada do Araripe (Araripe plateau) and all extension of planalto da Ibiapaba (Ibiapaba plateau), in altitudes between 600 and 900 m. Melipona quinquefasciata lives in the phytocoenosis of cerrado (Brazilian savanna), cerradão (savanna forest) and carrasco (montane deciduous shrub vegetation) on the top of Araripe plateau, and only carrasco in the Ibiapaba plateau. Due to pressures caused by reduction of the area covered with native vegetation, large use of agrochemicals in anthropic areas and generalised predatory hunting of honey and beeswax, M. quinquefasciata is in risk of disappearing from the ecosystems of Araripe and Ibiapaba plateaus within a few years.

The Ubatiba river is a coastal stream subject to stochastic spates all over the year and, Characidium sp.n. is among the twenty-two species that compose its ichthyofauna. In this study we analyse some traits of its reproductive biology and discuss whether the adopted strategy has causal relationship with the environmental variables. Specimens were collected in the upper Ubatiba river. Samplings, were carried out monthly by electrofishing, between Oct./94 and Sep./95. Some differences between male and female strategies were observed. Females were significantly (p < 0.05) bigger than males; length -- weight relationship was different (p < 0.05) between sexes with the onset of sexual maturity occuring at smaller sizes among males. Reproductive investment is high for both males and females but higher for males, maximum Gonadosomatic Index for females and males were 40.97% and 44.90%, respectively. Reproductive specimens were registered all over the year, suggesting continuous reproduction. High values of fecundity were also registered varying from 1342 to 5535 eggs for ripe females of 4.4 and 7.0 cm, respectively and an amount of 1105 oocytes per grams of fish. We suggest that differences in the reproductive strategy, between sexes, determine the observed patterns in the size structure; the absence of males in the higher SL classes could be a consequence of high mortality rates and/or reduction in the growth rates as a precocity consequence in the onset of reproduction and/or high reproductive investment. Relationship between continuous reproduction and environmental condition could be explained as an adaptation to maximise supervivency of the young fishes that is: guarantee the species maintenance in a stochastic environment.

Lepidosiren paradoxa (pirambóia) is the single representative of Dipnoan (lungfish) in South America. This species is considered a living fossil, in spite of some reports describing this fish as having a very specialized life style. It aestivates during the dry season, and has developed metabolic adaptations to cope with both flooding and drought. The literature describing its tissue ultra-structure shows high glycogen stored in the muscle, suggesting a strong dependence on anaerobic glycolysis. The present paper reports tissue enzyme levels of LDH, MDH, and CS, and isozymic tissue distribution of LDH, MDH, ADH, PGI, SOD, and PGM of 7 aestivating specimens from Lago do Canteiro in the Amazonas River. Animals were caught while burrowed in mud during the aestivation period. Our findings reveal high anaerobic capacity of both skeletal and heart muscles, even during the aestivation period, when enzymes showed suppressed levels compared to those of non-aestivating animals (data from the literature). Isozymic patterns suggest loss of duplicate condition in most analyzed loci, a characteristic that occurs mainly in higher vertebrate categories. These data indicate that, compared to the fish group, lungfish may be considered advanced, despite retaining primitive morphological characters.

In this study we analyzed a population of Bradypus torquatus with individuals originally distributed in different localities of Bahia, and two populations of B. variegatus with individuals from Bahia and São Paulo States. Using the DNA fingerprinting method, we assessed the genetic variability within and between populations. Analysis of the DNA profiles revealed genetic similarity indices ranging from 0.34 ± 0.07 to 0.87 ± 0.04. Similar low levels of genetic variability were found only in isolated mammalian populations or among related individuals. This study presents the first analyses of genetic diversity in sloth populations.

Rotifer production in a shallow artificial lake (Lobo-Broa Reservoir) was studied for twenty consecutive days between August 25, 1995 and September 13, 1995, during the dry season. Two species were dominant, during this period namely Filinia pejleri and Keratella americana, contributing, respectively, 36% and 28% to total rotifer numbers. Production estimates of these species were, respectively, 41.93 and 80.70 µg dry weight.m-3.d-1, corresponding to 18.45 and 35.51 µgCm-3.d-1. The population of F. pejleri was numerically more abundant than that of K. americana, while the production of the former was less, as a result of lower egg to female ratios.

Both the presence of receptors for gonadal steroids in the pineal gland and in vitro observations of direct action of melatonin upon Leydig cells, inhibiting testosterone secretion, indicate a direct connection between pineal gland and gonadal function. In the present study, we used a transmission electron microscope to analyze the morphologic parameters of Leydig cells from adult Swiss outbred white mice treated with daily subcutaneous injections of 100 µg of melatonin (N-acetyl, 5-methoxytryptamine), during 22 consecutive days, compared with sham-control animals which had only received the melatonin vehicle. The melatonin group of mice showed a decrease in nuclear volume and fractional nuclear volume; smooth and rough endoplasmic reticulum; mitochondria; and Golgi complex. Our data also showed an increase in cytoplasmic volume, fractional cytoplasmic volume, and lysosomes in these same animals. The results suggest that melatonin, directly or indirectly, alters the ultrastructure of mouse Leydig cells and possibly influences their secretory activity by inhibiting their capacity to secrete steroids.