Brazilian Wetlands Research Articles

Genotoxic evaluation in two amphibian species from Brazilian subtropical wetlands

Biomarkers analysis serves as an early warning system for the presence of pollutants because their responses appear before irreversible damage to the ecosystem takes place. The genotoxic effects of pollutants may occur at cellular pollutant concentrations that are well below levels that would cause gross cytotoxicity, making this a useful tool to detect early effects of toxic environmental agents. Combining the importance of Brazilian wetlands to the conservation of amphibian biodiversity with the potential negative impacts of irrigated rice fields in the surrounding areas, the aim of the present study was to evaluate genotoxic damage in two amphibian species, Pseudis minuta, and Leptodactylus gr latrans, from the southern Brazilian wetlands. Adult specimens from both Anuran species were captured from preserved (Taim Ecological Station=TAIM) and non-preserved (Senandes) wetlands. Nuclear abnormalities were quantified in erythrocytes, and the results were compared using the Mann–Whitney U test. There was a higher incidence of micronucleated erythrocytes in P. minuta, and of notched nuclei in L. gr latrans that were collected in TAIM when compared to those that were collected in Senandes, despite the fact that TAIM is a conservation unit. These findings indicate that Anurans are coping with genotoxic substances in their habitats, and underscore the need to implement monitoring programs in TAIM to determine which compounds or mixtures might be causing cell damage and to investigate the effects of such compounds on other anuran species and animal groups.

Nonheterocytous cyanobacteria from Brazilian saline-alkaline lakes.

Saline-alkaline lakes are extreme environments that limit the establishment and development of life. The Nhecolândia, a subregion of the Pantanal wetland in Brazil, is characterized by the existence of ~500 saline-alkaline lakes, which support an underexplored and rich diversity of microorganisms. In this study, unicellular and homocytous cyanobacteria from five saline-alkaline lakes were accessed by culture-dependent approaches. Morphological evaluation and analyses of near complete sequences (~1400 nt) of the 16S rRNA genes were applied for phylogenetic and taxonomic placement. This polyphasic approach allowed for the determination of the taxonomic position of the isolated strains into the following genera: Cyanobacterium, Geminocystis, Phormidium, Leptolyngbya, Limnothrix, and Nodosilinea. In addition, fourteen Pseudanabaenales and Oscillatoriales representatives of putative novel taxa were found. These sequences fell into five new clades that could correspond to new generic units of the Pseudanabaenaceae and Phormidiaceae families.

Genetic differentiation among populations of the Roseate Spoonbill (Platalea ajaja; Aves: Pelecaniformes) in three Brazilian Wetlands.

Effective population size, levels of genetic diversity, gene flow, and genetic structuring were assessed in 205 colonial Roseate spoonbills from 11 breeding colonies from north, central west, and south Brazil. Colonies and regions exhibited similar moderate levels of diversity at five microsatellite loci (mean expected heterozygosity range 0.50-0.62; allelic richness range 3.17-3.21). The central west region had the highest Ne (59). F ST values revealed low but significant genetic structuring among colonies within the north and within the south regions. Significant global genetic structuring was found between the northern and central western populations as well as between the northern and southern populations. An individual-based Bayesian clustering method inferred three population clusters. Assignment tests correctly allocated up to 64% of individuals to their source regions. Collectively, results revealed complex demographic dynamics, with ongoing gene flow on a local scale, but genetic differentiation on a broader scale. Populations in the three regions may all be conserved, but special concern should be given to central western ones, which can significantly contribute to the species' gene pool in Brazil.

Austrolebias quirogai (Actinopterygii: Cyprinodontiformes: Rivulidae) in Brazil: occurrence, population parameters, habitat characteristics, and conservation status

Background. The Neotropical genus Austrolebias is the most diverse of the Rivulidae family, with 22 species recorded in Brazil, with 21 found in the state of Rio Grande do Sul. Austrolebias quirogai Loureiro, Duarte et Zarucki, 2011 is an annual fish previously only found in Uruguay and there is currently no information about their ecology and life history. Here, we recorded A. quirogai for the first time in temporary wetlands in Brazil. Furthermore, we provide information about population parameters, life history traits, conservation status, and habitat characteristics. Materials and methods. We captured the fish with a D-shaped hand net in a sampling survey carried out in October 2012 in the Jaguarão-Chico River, Aceguá municipality, Brazil. We analysed density (CPUA), body size, length–weight relation (LWR), condition factor (K), and sex ratio. Results. We recorded a total of three populations of Austrolebias quirogai in the Jaguarão-Chico River. The CPUA was 0.33 fish · m–2. The sex ratio relation did not differ significantly and was 1.5 : 1 (M : F). The mean body size between sexes was not statistically different. The LWR of A. quirogai was W = 0.011TL3.23. The value of parameter b was significantly different from 3.0 for males and females, both sexes presenting positive allometric growth. The K for A. quirogai differed between sexes. Females had higher values than males. All populations of A. quirogai were found in ponds smaller than 1000 m² and were degraded by the activity of rice and soybean cultivation and overgrazing. We consider A. quirogai an endangered species in Brazil because of: its reduced area of occupancy, populations becoming severely fragmented, and suffering a continuous decrease in their area of occupancy and the quality of habitat. Conclusion. The observed results may be used to assist the development of management strategies and conservation of the species and its habitat. Moreover, they provide basic information for the evaluation of the conservation status of the species according to IUCN criteria and for the definition of priority areas for conservation in southern Brazil. Further studies should focus on the distribution, life history and ecology of the species to aid in their conservation.

Chemical diversity and spatial variability in myriad lakes in Nhecolândia in the Pantanal wetlands of Brazil

Nearly 15,000 shallow, saline or freshwater lakes and ponds coexist in close proximity in the Nhecolândia, a 24,000 km2 subregion of the Pantanal wetland in Brazil. This study aims to understand the origin of such diversity in surface water, which is a key aspect for the wetland services and biodiversity in the region. Both soil observations and water samples were collected at the regional or local scale and supplemented by previously published data sets. Statistical and geostatistical treatments were carried out and completed by discrete water‐table monitoring. The results confirmed the absence of a regional pattern in surface‐water salinity, and the independence of electrical conductivity values, even for neighboring lakes. Despite great differences in chemical composition, all surface waters in the region belong to the same chemical family, corresponding to several concentration stages of the Taquari River water that supplies the region. The concentration stage depends on the hydrological functioning of each lake, which is itself controlled by the relative importance of low‐permeability soils as a barrier to movement of water into or out of the lakes through the subsurface. In this framework, oligosaline ponds, freshwater lakes, and saline lakes work as recharge, flow‐through, and discharge wetlands, respectively. The salinity observed in some lakes results from an ongoing process of accumulation and evaporation under relatively humid climatic conditions and poor drainage.

Brazilian wetlands: their definition, delineation, and classification for research, sustainable management, and protection

ABSTRACT Although 20% of Brazilian territory is covered by wetlands, wetland inventories are still incomplete. In 1993, Brazil signed the Ramsar Convention but a coherent national policy for the sustainable management and protection of wetlands has yet to be established. Major gaps in the definition of a specific wetland policy are twofold: (1) the lack of standardized criteria by which wetlands are defined and delineated that reflects the specific ecological conditions of the country and (2) the lack of a national classification of wetlands that takes into account specific hydrological conditions and respective plant communities. In recent years, efforts have been made at a regional level to improve public awareness of the ecology of Brazilian wetlands, their benefits to society, and the major threats endangering them. Studies have shown that wetlands play a crucial role in the regional hydrological cycle and provide multiple benefits for local populations. Furthermore, Brazilian wetlands contribute significantly to South American biodiversity. Therefore, wetland conservation and sustainable management should be given high legislative priority. This article provides a synthesis of the current body of knowledge on the distribution, hydrology, and vegetation cover of Brazilian wetlands. Their definition, delineation, and classification at the national level are proposed in order to establish a scientific basis for discussions on a national wetland policy that mandates the sustainable management of Brazil's extremely diverse and complex wetlands. This goal is particularly urgent in the face of the continuing and dramatic deterioration of wetlands resulting from large‐scale agro‐industrial expansion, and hydroelectric projects as well as the projected impact of global climate change on hydrological cycles. Copyright © 2013 John Wiley & Sons, Ltd.

The Imperial Palm (Roystonea oleracea (Jacq.) O.F. Cook) as an invasive species of a wetland in Brazilian Atlantic forest

The aim of this research was to study the population structure of an exotic palm, Roystonea oleracea (Arecaceae), map its spatial distribution and investigate its invasive status in an Atlantic forest wetland. A total of 130 live and 7 dead standing palms ≥10 cm DBH were sampled. Data showed a trend towards population expansion, with most seedlings and saplings occurring within a radius of ~12 m from the mother plants but some larger trees (DBH >10 cm) up to 440 m from the parents. This exotic species is established and has the potential to become invasive, especially near wetlands. Its control or eradication should be undertaken and we suggest the immediate removal of reproductive individuals, and constant monitoring of young individuals leading to their future removal. Use of this species as an ornamental should be made with care to prevent or reduce possible harmful effects of this exotic and potentially invasive species in Brazilian wetlands.

Serological and molecular investigation of the prevalence of Aujeszky's disease in feral swine (Sus scrofa) in the subregions of the Pantanal wetland, Brazil

The feral swine (FS) originated from the domestic pig and is present throughout the Brazilian wetland plain (the Pantanal). Aujeszky's disease (AD) was first serologically confirmed in the state of Mato Grosso do Sul (MS) in 2001; however, there was no viral confirmation. The aim of this study was to investigate antibodies against-SuHV-1 in the sera of feral swine in the studied areas, detect SuHV-1 through PCR and classify the viral genome. Among the 218 animals sampled, 186 were analyzed by ELISA, resulting in 88 (47.3%) reactive samples. In the serum neutralization test (SN), 57/179 (31.8%) samples presented antibodies against the AD virus (SuHV-1). By nested PCR, 104 DNA samples were extracted for analysis and confirmed with amplification of a fragment of glycoprotein B (gB) in five samples. The SuHV-1 was detected in 12 samples by using primers for glycoprotein E (gE) and viral genome was classified as Type I by ul44 partial sequencing. The amplification of SuHV-1 glycoprotein fragments in the fetuses of seropositive sows indicate that the vertical transmission contribute to maintain SuHV-1 in a free-living feral swine population. The origin of AD in the feral swine populations of the Pantanal is unknown, however, the determination of viral latency, the vertical transmission of the antigen by the amplification of SuHV-1 glycoprotein fragments in the fetuses of seropositive sows and genome typing contribute to the elucidation of the epidemiology of this disease in the wetlands of MS, Brazil.

Haementeria lutzi Pinto, 1920 (Hirudinea: Glossiphoniidae) as a putative Vector of Trypanosoma evansi (Kinetoplastida: Trypanosomatidae) in the Pantanal Matogrossense (MS, Brazil)

In the present study, it was shown under experimental conditions that Trypanosoma evansi could be mechanically transmitted to Rattus norvegicus by leeches (Haementeria lutzi). Additionally, we also described some aspects related to the behavior of the Trypanosoma evansi in the leeches after an infective blood feeding, as follows: a) 10 minutes after the parasites were ingested; they promptly progressed to the coelomic cavity. b) Approximately, from 10 to 30 minutes inside the gut, rounded and dividing forms together with stumpy and slender trypomastigotes showed a random dispersion. c) 24 hours after, the trypanosomes also invaded both, the salivary glands as well as the proboscis cells. Our results suggest that leeches of the species Haementeria lutzi could have some role as a probable alternative vector of Trypanosoma evansi at wetlands in Brazil.

Geothermal Dynamics in Vochysia Divergens Forest in a Brazilian Wetland

Research involving the thermal soil dynamics of wetland areas has not yet been explored in a way that promotes a deeper understanding of the dynamics of this region. This makes it necessary for further studies to contribute to the understanding of this biome. In the present work, we studied the thermal dynamics of the soil contrasting seasonal conditions in the Vochysia Divergens Forest. The Fourier equation was used to analyze the influence of the thermal conductivity and thermal gradient on the soil heat flux. We determined how variable water content causes the system to behave differently in the four seasons, observing seasonality in soil when completely dry and when completely flooded.

Subsídios para a proteção de áreas úmidas da bacia do rio Xingu (Mato Grosso, Brasil)

O rio Suiá-Miçu é um importante tributário do rio Xingu, e sua bacia hidrográfica (BHSM), situada no planalto do Parecis, Estado de Mato Grosso, abrange 2,36 milhões de hectares. A BHSM contempla Formações Pioneiras, Cerrados e a Floresta Estacional Perenifólia, cuja composição de espécies é consequência da variabilidade de chuvas e do clima estacional. O objetivo deste trabalho foi caracterizar as áreas úmidas da BHSM e sua importância para a preservação ambiental. O mapeamento da BHSM foi realizado a partir do georreferenciamento de imagens do satélite CBERS-2 (2006), que resultou em um mosaico RGB234 com 20 m de resolução. Esse mosaico permitiu o mapeamento de todas as drenagens da BHSM e, assim, a definição da planície de inundação, complementada pelo cruzamento dos mapas de hidrografia e geomorfologia e trabalhos de campo. Os resultados indicaram mais de 192 mil hectares de área de inundação, dos quais 13% foram desmatados para usos agropecuários. As áreas úmidas da BHSM têm papel importante no suprimento de água durante as estações secas. São compostas de hábitats fluviolacustres e de uma diversidade de vegetação que abarca os campos úmidos, a floresta inundável e as veredas (dominadas pelo buriti Mauritia flexuosa). Apesar de no Brasil existirem leis ambientais para proteção de cursos d'água e das áreas marginais, sua implementação e monitoramento são necessários, dada a fragilidade de ecossistemas presentes na planície de inundação, como no caso da BHSM. Recomendam-se mais pesquisas científicas sobre esses ecossistemas para apoiar as tomadas de decisão na proteção das áreas úmidas no Brasil.

Cytogenetic characterisation of the ornamental freshwater fish, Piabucus melanostomus (Iguanodectinae) from Brazilian wetlands and its relation with species of Characidae basal group

The genus Piabucus is the only member of the subfamily Iguanodectinae found in the Pantanal of Mato Grosso State, where it is represented by Piabucus melanostomus. P. melanostomus from the Paraguay and Bento Gomes Rivers of the Pantanal wetlands were analysed using conventional and molecular cytogenetic techniques to cytogenetically characterise the species and broaden the knowledge of the subfamily. The results indicated no sex-related heteromorphisms. The diploid number for the species was 2n = 50 chromosomes, which were divided into six metacentric, eight submetacentric, 24 subtelocentric, and 12 acrocentric with a fundamental number (FN) of 88. Heterochromatin was visualised using the C-banding technique, which showed that it was mainly distributed in the centromeric and pericentromeric region of most chromosomes, but larger blocks were observed on the long arms of large subtelocentric chromosomes (8, 9, 10, 13, and 20 pairs). Nucleolar organising regions (Ag-NOR) were observed in the p-subterminal region of one subtelocentric chromosome pair (9) with a remarkable size polymorphism between homologues in individuals from the Paraguay River, which was confirmed using the FISH technique with 18S rDNA. In this population, in all individuals studied, one of the homologous shows block considerably larger. The karyotype was compared with those of other subfamilies considered basal in Characidae, according to morphological data.

Parasitism rates of Lipoptena guimaraesi and a new record of Lipoptena mazamae on Ozotoceros bezoarticus from the Central Pantanal wetlands in Brazil

From May to October of 2006 we collected 143 louse flies of the genus Lipoptena on the body surface of 16 pampas deer Ozotocerus bezoarticus captured in four farms from the central area of the Brazilian Pantanal wetlands. We also examined 172 cattle individuals and none of them had louse flies. Most of the parasites identified were Lipoptena guimaraesi but one specimen of L. mazamae was also found, representing a new host record for this ked fly. The prevalence of L. guimaraesi was 93.8%, the mean intensity of infestation was 9.5, and the index of discrepancy was 0.444.

Diversity of aquatic macrophytes in the Lagoa do Peixe National Park

Floristic surveys are significant tools to get to know species diversity and distribution. Little is known about the diversity of aquatic macrophytes in the palustrine wetlands of the Lagoa do Peixe National Park. The goal of this study was to survey aquatic macrophytes in the park wetlands. It identified 176 aquatic macrophyte species distributed in 98 genera and 44 families. Families with the largest number of species included Cyperaceae, Poaceae, Juncaceae, and Asteraceae. The most diverse genera were Eleocharis (14 species), Juncus (10 species), Cyperus (7 species), Utricularia (7 species), Rhynchospora (6 species), and Ludwigia (6 species). The most frequent species were Hydrocotyle bonariensis, Centella asiatica, Ischaemum minus, Nymphoides indica. The predominant biological forms were amphibious (45% of the species) and emergent (28% of the species) macrophytes. The floating ones represented 16% of the species, and the submerged macrophytes represented 11% of the species. The diversity of the palustrine wetlands is high and comparable to other extensive wetlands in Brazil, such as Pantanal and Taim. The information in this study is important to improve the knowledge about the biological diversity of the National Park. Key words: Lagoa do Peixe, floristic survey, aquatic plants, biological forms.

Historical reconstruction of floodplain inundation in the Pantanal (Brazil) using neural networks

Summary The relations between hydrology, geomorphology and vegetation provide the basis for understanding the ecological processes in the floodplains of rivers. In this paper, long-term (1969–2009) local flood characteristics (magnitude, duration, frequency, return period) are quantified for the floodplain of the Cuiaba River (Pantanal wetland in Brazil), using a predictive model based on artificial neural networks (ANNs) with input given by the historic river-level record. Morphological features were then described and their relation to vegetation analyzed and used to reconstruct floods. In addition to the river-level data used to train and validate a three-layer ANN, data were also used from 11 floodplain gauges across a 12 km transect lateral to the river, which were monitored during the annual floods of 2004–2007. The resulting neural network gave satisfactory estimates of water depth over the floodplain, with an absolute error of 0.09 m not exceeded in 95% of occurrences. The ANN showed that in almost all years, the level reached by the river was high enough to flood the profile completely: the exceptions were 1971 and 2001 when only 50% and 58% was flooded, to mean depths of 0.34 and 0.48 m, respectively. The highest flood was that of 1995 when the floodplain was flooded to a mean depth of 2.56 m. The median flood event (return period 2 years) produced a mean flood depth 1.80 m and lasted 119 days. Among the most important morphological features is the presence of palaeo-channels which provide hydrological connectivity between the river and the floodplain. The distribution of phytophysiognomic units is significantly influenced by local geomorphology, which determines spatial variation in the magnitude, duration, and frequency of flooding.

Mapping a wetland complex in the Brazilian savannah using an Ikonos image: assessing the potential of a new region-based classifier

The Pandeiros is a unique wetland in northern Minas Gerais, Brazil. Even though it is an official wildlife sanctuary, it suffers from increasing degradation because of livestock grazing and other forms of human activity. The absence of specific laws defining and protecting wetlands in Brazil is partly responsible for this situation. Having no official designation, most environments of the Pandeiros have not yet been identified or characterized as wetlands. This article presents a comparison between an unsupervised region-based classification approach and traditional supervised and unsupervised classification techniques for mapping different environments within this complex wetland system. All three classification methods were tested and their results compared with field data and with an interpreted reference map. The results suggest that the traditional supervised classification approach and the new region-based approach have good potential for identifying the main vegetal physiognomies, but the latter yielded superior results, with an estimated accuracy of 95% compared with 88% for the former. The region-based approach had the advantage of a much superior spatial consistency and allowed easier visual interpretation of the classified image. In a second accuracy assessment, we compared the results with a visually interpreted reference map and obtained total accuracies of 70%, 41%, and 39% for the region-based, maximum likelihood, and unsupervised ISODATA algorithms, respectively.

A systematic evaluation of the conservation plans for the pantanal wetland in Brazil

The Pantanal is the world's largest contiguous freshwater wetland spanning Brazil, Bolivia, and Paraguay. It contains the greatest wildlife densities in the Neotropics and was enlisted by all three countries in the Ramsar convention on wetland conservation. The Brazilian government, together the UNESCO's Man and the Biosphere Program, declared a biosphere reserve in the Pantanal in 2000. Other plans to protect the region include expansion of existing reserves and land use regulations following recommendations from the Cerrado-Pantanal priority setting workshop. Here we evaluated how four conservation scenarios complied with the principles of systematic conservation planning and analyzed their representativeness, efficiency, and complementarity using 17 vegetation classes as surrogates for regional biodiversity. We used MARXAN (systematic conservation planning software) to determine the value of the habitat types protected by each conservation scenario. We found that none of the four conservation scenarios met preferred areal targets for protection of habitats, nor did any protect all 17 biodiversity surrogates. The Pantanal Biosphere Reserve provided the best compromise in conservation planning.

Can management practices in rice fields contribute to amphibian conservation in southern Brazilian wetlands?

Abstract Rice field expansion is one of the activities associated with the disappearance of 90% of the wetlands in southern Brazil. Worldwide, rice agriculture has been recognized as having considerable potential value for many aquatic species. Nevertheless, management practices in such systems must be ameliorated and better investigated. This study evaluated the potential role of rice fields as refugia for amphibians, and whether different hydrologic management practices after rice cultivation could contribute to wetland amphibian conservation in southern Brazil. Six collections were made in six rice fields with different management practices after cultivation (three dry and three flooded) and three natural wetlands. The amphibians were sampled through six random 15‐min visual transects per collection in each rice field and the natural wetlands. In total, 2139 anuran individuals were observed in rice fields (798) and Reserva Lake (1341), comprising 12 anuran species distributed among five anuran families. Anuran richness and abundance varied over the rice cultivating cycle, and they were higher in the growing phases than in the fallow phases. The mean anuran richness and abundance was higher in Reserva Lake than in flooded and dry rice fields. The different management practices adopted after the harvesting period (presence or lack of surface water) did not influence the anuran richness and abundance. It did, however, influence species composition. The difference in species composition between the management practices adopted is an interesting result in terms of biodiversity conservation. Rice producers could maintain part of their agricultural land flooded during the fallow phase as a strategy to preserve a higher diversity of anurans. These results should be taken into consideration in wetland conservation plans in southern Brazil; however, the percentage of each agricultural land that should be kept flooded should be decided by Brazilian agricultural and conservation policies. Such a strategy would reconcile agricultural/economic needs with the conservation of biodiversity in southern Brazil, where more than 90% of wetland systems have already been lost. Copyright © 2009 John Wiley & Sons, Ltd.

Fish communities of the Pantanal wetland in Brazil: evaluating the effects of the upper Paraguay river flood pulse on baía Caiçara fish fauna

The physicochemical variables and the ichthyofauna associated with aquatic macrophyte beds in two stretches of the baia Caicara were evaluated seasonally between September 2005 and May 2007. Low depth, high water transparency, and relatively well-oxygenated waters characterized both stretches during the low water season, whereas the flooding of the upper Paraguay River correlated with drastic alterations in these variables: depth registered a fivefold increase, and turbid and anoxic waters predominated during the high water season. During the falling and low water seasons, species richness, fish abundance, biomass, and diversity were significantly higher than during periods of rising and high waters. The presence of large-sized migratory species, however, was strictly associated with the high water season. The results suggest strong relationships between the abiotic and biotic components of the system and indicate an overall high degree of dependence of the system on the hydrological seasonality of the upper Paraguay River.

Continuous growth of the giant grass Zizaniopsis bonariensis in subtropical wetlands

Summary1. Zizaniopsis bonariensis (giant grass) is an emergent macrophyte species endemic to subtropical wetlands in Brazil, Argentina, Paraguay and Uruguay. In this study, we show the effects of its continuous clonal reproduction and its ‘phalanx’ growth strategy in the Taim Wetland (southern Brazil).2. The continuous clonal growth of this 3‐m high grass gave rise to the emergence of 11.7 new shoots m−2 per month and a high total above ground production (2870 g dry weight m−2 year−1). The biomass of the new shoots emerging every month formed a wave of growth, moderated by only weak seasonal variation.3. We show its phalanx growth strategy by analysing the variations in population density and shoot height within a transect through the stand canopy. The inverse relation between density and height from the border to the interior indicates self‐regulation of biomass.4. The plants modified their environment, enhancing resistance to drought within the stand and thus facilitating their dominance. This positive feedback suggests that the dominance of the plant might constitute an alternative state in subtropical wetlands.