Spatial heterogeneity affecting fish fauna in cascade reservoirs of the Upper Paraná Basin,Brazil

In cascade reservoirs, different zonation effects can be observed along the longitudinal axis, depending on the retention time of each reservoir. In this study, we evaluated the relationships among fish and spatial and environmental variables across longitudinal zones within reservoirs with different retention times. Fieldwork was carried out during two periods in three different zones that represent the longitudinal axis (lotic, transitional, and lentic) of three reservoirs. Each reservoir has different retention times (low, intermediate, and high) and all are located in a cascade system of the Paranapanema River, Brazil. In the high retention time reservoir, richness, biomass, and diversity decreased along the longitudinal axis, in contrast to the numerical abundance and dominance. Conversely, in the low retention time reservoir, these community attributes varied in an opposite way. Both spatial (depth, retention time, longitude, and latitude) and environmental (dissolved oxygen, water temperature, Secchi disk, total nitrogen) variables were important controlling factors for fish communities in reservoirs, which confirms the hypothesis that reservoir retention times create a zonation effect with different proportions along the main axis, resulting in a spatial heterogeneity with specific environmental features, and it determines the fish assemblage structure and composition in each reservoirs.     

Allozyme Analysis of Hypostomus (Teleostei: Loricariidae) from the Rio Corumbá, Upper Rio Paraná Basin, Brazil

The taxonomy of the genus Hypostomus in the upper Rio Paraná basin presents some very complex issues. For this reason, an allozyme electrophoresis survey of 10 populations of Hypostomus from the Rio Corumbá basin was performed, revealing 25 loci from 14 enzyme systems. Allozyme data revealed diagnostic genetic markers for the four nominal species analyzed (Hypostomus ancistroides, H. iheringi, H. margaritifer, and H. regani) and for six possible undescribed species. The mean expected heterozygosity of the populations ranged from 0.009 in H. iheringi to 0.099 in Hypostomus sp. 4. The genetically most similar populations (I = 0.954) were H. iheringi and Hypostomus sp. 2; the most divergent (D = 0.839) were H. iheringi and H. ancistroides.     

Description of Freshwater Bacterial Assemblages from the Upper Paraná River Floodpulse System,Brazil

Bacteria were identified from a large, seasonally flooded river (Paraná River, Brazil) and two floodplain habitats that were part of the same river system yet very different in nature: clearwater Garças Lagoon and the highly humic waters of Patos Lagoon. Bacterioplankton were collected during mid-summer (Jan. 2002) from water samples (2 l) filtered first through a 1.2-μm filter then a 0.2-μm membrane filter representing the particle-attached and free-living sub-communities, respectively. DNA was extracted from filters and purified and a 16S rRNA clone library established for each habitat. Over 300 clones were sequenced and checked for similarity to existing 16S sequences in GenBank using the BLAST algorithm with default parameters. Further classification of clones was done using a species “backbone” attachment followed by parsimony analysis. The majority (85%) of sequences, referred to here as operational taxonomic units (OTUs), were most similar to uncultured bacterium 16S sequences. OTUs from each Proteobacteria sub-phylum (α, β, γ, δ, ?) were present in the Upper Paraná River system, as well as members of the Bacteroidetes. The microbial assemblage from Patos Lagoon was least like other samples in that it had no Firmicutes present and was dominated by Actinobacteria. Verrucomicrobia OTUs were only found in the free-living assemblage. This study documents the presence of globally distributed phyla in Upper Paraná River and taxa unique to habitat and particle attachment.     

Reproduction of the South American Dogfish Characid, Galeocharax knerii, in Two Reservoirs from Upper Paraná River Basin, Brazil

We analysed the reproductive biology of the dogfish characid, Galeocharax knerii, by histological and ultrastructural techniques during two consecutive annual cycles at the Furnas and Itumbiara reservoirs, upper Paraná River basin, Southeastern Brazil. We classified the ovaries as cystovarian with asynchronous oocyte development and the testes as anastomosing tubular and unrestricted spermatogonial. Spermatogenesis is cystic and the spermatozoa have a rounded head, short middle piece and a long tail that contains microtubules in a 9 + 2 axonemal arrangement. Oogenesis occurs in ovigerous lamellae that project into the ovarian cavity. Vitellogenic oocytes possess a zona pellucida that is folded around the micropyle in an arrangement that facilitates fertilisation and which is also seen in other characids. Although the reservoirs of Furnas and Itumbiara have similar geomorphology and ichthyofauna, the biological parameters (e.g., gonadosomatic index) indicated more favourable conditions for reproduction of G. knerii in Itumbiara. An extended reproductive period, multiple spawnings and continuous spermatogenesis were the main reproductive characteristics of this species. We conclude that G. knerii has an opportunistic reproductive strategy, characterised by absence of parental care, early maturation and continuous reproduction, that also occurs in other neotropical characids, and allows them to rapidly colonise most of the reservoirs of the Southeastern Brazil.     

Hydrologic and climatic regimes limit phytoplankton biomass in reservoirs of the Upper Paraná River Basin,Brazil

In reservoirs of the Upper Paraná River Basin, Brazil Paraguay, phytoplankton biomass is generally low relative to reservoirs in other parts of the world. To investigate what might be limiting phytoplankton biomass in the Upper Paraná reservoirs, we used an empirical approach wherein climatic conditions in the basin as well as chemical, hydrological and morphometrical characteristics of 13 reservoirs, were compared against those prevailing in 58 reservoirs of the south-central United States. In both regions, phytoplankton biomass was correlated with chemical, hydrological and morphometrical characteristics of the reservoirs. There were no differences in phosphorus concentrations between the two regions, nitrogen levels were higher in the Upper Paraná, ionic concentrations were higher in the south-central United States and there were major differences in all physical characteristics considered. In reservoirs of the south-central United States, hydraulic retention time increased and discharges decreased during the post-spawning period allowing increases in phytoplankton biomass; in the Upper Paraná River Basin, discharges peaked during the post-spawning period, delaying the peak of phytoplankton blooms until after completion of the post-spawning period. Our comparison between the two sets of reservoirs suggests that hydrologic regimes dictate differences in phytoplankton biomass and that hydrology of the Upper Paraná River Basin, exacerbated by climatic patterns, deter phytoplankton production despite suitable levels of essential nutrients.     

A new species of Cambeva (Siluriformes,Trichomycteridae) from the Rio Ivaí basin,Upper Rio Paraná basin,Paraná State,Brazil

A new species of Cambeva endemic to the Rio Ivaí basin, Upper Paraná basin, is described combining morphological and molecular data. This new species is distinguished from all congeners by characters related to the number of pectoral-fin rays, to the colour pattern of the dorsal and lateral surface of the body, to the presence of diffuse blotches in the ventral surface of body, to the presence of a pelvic-fin and pelvic girdle, to the number of odontodes in the inter-opercular and opercular patches, to the number of dorsal and ventral procurrent rays. In addition, the analysis of mitochondrial DNA sequences identified a satisfactory genetic distance between this new species and its congeners. The new species from the Rio Ivaí reinforces its characteristics as an area of endemism for fishes in the Upper Rio Paraná basin.     

Spatial and temporal variations of oligochaetes of the Ivinhema River and Patos Lake in the Upper Paraná River Basin,Brazil

The composition and spatial and temporal variation of oligochaete community were analyzed in Patos Lake and Ivinhema River, a tributary of the Paraná River Brazil, during the period March 1993 to February 1994. Lentic and lotic environments were studied, with the objective of analyzing species association and temporal changes in the function of the abiotic variables at nine sites studied. Seventeen species of oligochaetes were identified. Oligochaete association was analyzed by Detrended Correspondence Analysis (DCA) and abiotic variables, by Principal Components Analysis (PCA). This method showed that Aulodrilus pigueti predominated in Patos Lake, probably because it has adapted to mud with high organic matter in low currents. Brinkhurstia americanus predominated at the right bank of the Ivinhema River while Paranadrilus descolei predominated at the left bank. Temporal variation of organism density was influenced by hydrological cycle, and spatial variation was determined by grain size and quantities of organic matter in the sediments.     

Lepidophylloides corumbataensis sp. nov. from the Guadalupian in the Paraná Basin,southern Brazil

A new species of the isoetalean leaf genus Lepidophylloides is described. This Guadalupian species from the Paraná Basin, Lepidophylloides corumbataensis, found as silicified microphylls in the Corumbataí Formation in the municipality of Piracicaba, São Paulo state, in southern Brazil, is the first species of the genus to be formally described for Brazil, and possibly the first for Gondwanaland. This is also the first time that surviving palisade tissue has been found in a species of Lepidophylloides. The new species is compared to known species and shown to be distinct from all previously described from Euramerican and Cathaysian floras. The organization of the xylem in arch-like or crescent-shaped bundles suggests a relation to Cathaysian species. The close association with Lycopodiopsis derbyi stems (which have true leaf scars and must have suffered leaf abscission) suggests that they are different organs from the same species.     

Paleosols and host rocks from the Middle–Upper Permian reference section of the Kazan Volga region,Russia: A case study

The Urzhumian (Wordian) and Severodvinian (Capitanian) reference section of the Monastery Ravine (Kazan Volga region, Russia), contains two siltstone lithofacies: (a) laminated and (b) massive. Depositional settings of the laminated siltstones can be interpreted as perennial to ephemeral lakes; depositional settings of the massive siltstones are interpreted as floodplains with soil cover and periodical silt influx in wet seasons. The bulk geochemistry of siliciclastics has revealed a high degree of weathering of both types of siltstone. The similar chemical composition, mineralogy, and grain size suggest the same provenance of silt material. Geochemical data indicate eastern source rocks, which are the Permian red beds of the Cis-Ural plains.The main genetic types of paleosols hosted in the massive siltstones in the studied section, include moderately developed Vertisols and Calcisols with drab-colored root traces, calcareous nodules, low chroma mottles, angular blocky peds and slickensides. These pedofeatures indicate in general a semi-arid climate with clear seasonality of rainfall. Major oxides of the paleosol matrix were used to estimate paleoprecipitation through the bases to alumina (ΣBases/Al) ratio and chemical index of alteration minus potassium (CIA-K) proxies. Estimates from Urzhumian paleosols indicate relatively low mean annual precipitation (MAP) of 390 mm/yr. The transition to the Severodvinian paleosols is marked by a noticeable MAP increase up to 777 mm/yr. This climate moistening coincides with changes in the morphology of paleosols from dolomitic with low redoximorphy to calcitic with gley horizons. The pedogenic carbonate nodules consisting of dolomicrite (5–10 μm) are very common in the Urzhumian paleosols and their morphology, micromorhology and isotopic features indicate the pedogenic origin of dolomite.Sedimentological and paleopedological features of the studied siltstones, as well as the location of the Volga-Ural basin in a mid-latitude position (25–32 °N) indicate a monsoonal character of precipitation during the Middle Permian.     

Length-weight relationships for seven endemic fish species from streams of the last two large remaining dam-free tributaries of the Upper Paraná River Floodplain in the Paraná State,Brazil

This study reports the length-weight relationships (LWR) for seven endemic fish species from streams in the Ivaí (Characidium heirmostigmata, Corydoras lacrimostigmata, Curculionichthys oliveirai, Hisonotus pachysarkos, and Cambeva horacioi) and Ivaí and Piquiri (Apareiodon vladii and Planaltina kaingang) River basins, Paraná State, Brazil. Fish specimens measured and weighed were collected between November 1994 and July 2019, fixed with 10% formalin, and are preserved in 70% alcohol. Measurements were done for standard length (SL—0.1 cm precision) and total weight (TW—0.01 g precision). All coefficient of allometry obtained is within the general range for fishes representing useful tentatives for LWR parameters. We highlight the importance of information about the biology of the endemic fish species in a crucial area for the biodiversity conservation of the Upper Paraná River system.     

Allozyme Differentiation of Four Populations of Hypostomus (Teleostei: Loricariidae) from Ribeirã;o Keller, a Small Stream in the Upper Rio Paraná Basin, Brazil

Hypostomus hermanni (Ihering, 1905) and three other morphotypes of the genus Hypostomus were collected from the Ribeirã;o Keller, a small tributary of Rio Ivaí, a tributary of upper Rio Paraná. An allozyme analysis of 25 gene loci revealed diagnostic loci alleles for each population and there were fixed differences between some of them at some loci. Thus all populations were genetically distinct, although there were many common alleles. Heterozygosity (H _e) ranged from 0.059 in Hypostomus sp. 2 to 0.144 in Hypostomus sp. 1 and was higher than the average for other species of Hypostomus and also for fish in general. H. hermanni and Hypostomus sp. 1 were more similar to each other (I= 0.878) whereas H. hermanni and Hypostomus sp. 2 showed the least genetic identity (I= 0.392).     

Allozyme relationships in hypostomines (Teleostei: Loricariidae) from the Itaipu Reservoir,Upper Rio Paraná basin,Brazil

In an allozyme electrophoresis survey of 15 hypostomine species from the Itaipu Hydroelectric Reservoir, 25 loci from 14 enzyme systems were scored. Allozyme data allowed recording diagnostic genetic markers for all species analyzed and for some species groups within Hypostomus, a taxon which is taxonomically still unresolved in the Upper Rio Paraná basin. The mean expected heterozygosity of the species was considerably variable and hypotheses to tentatively explain this variation are discussed. A cladogram based upon the allelic frequencies of the species analyzed was produced by the continuous maximum likelihood method: Rhinelepis aspera and M. parananus were separated from the species of Hypostominae by a long branch length. Pterygoplichthys anisitsi was the sister of all the representatives of the genus Hypostomus. Within Hypostomus, two main clades were produced: in the first, H. cochliodon was the sister of the species comprising the H. plecostomus group, and in the second, the tree showed the following relationships: (H. albopunctatus (H. regani + Hypostomus sp. 3) + (H. margaritifer (H. microstomus (Hypostomus sp. 1 (H. ternetzi + Hypostomus sp. 2))))). Hypostomus ternetzi and Hypostomus sp. 2 are referred to here as representatives of the H. ternetzi group.     

Carnivory during Ontogeny of the Plagioscion squamosissimus: A Successful Non-Native Fish in a Lentic Environment of the Upper Paraná River Basin

This study evaluated feeding patterns and ontogenetic variations in a non-native fish species (Plagioscion squamosissimus) in an isolated lake in the Upper Paraná River floodplain. Quarterly samplings were performed from April 2005 to February 2006 using plankton nets to capture larvae, seining nets for juveniles, and gill nets and trammel for adults. Stomach contents (n = 378) were examined according to the volumetric method in which the volume of each food item was estimated using graduated test tubes or a glass counting plate. During early development (larval stage), P. squamosissimus consumed mainly Cladocera and Copepoda. Juveniles showed a more diverse diet, including shrimp (Macrobrachium amazonicum), fish, aquatic insects (Trichoptera, Ephemeroptera, Chironomidae and pupae of Diptera) and plants. It was notable the high proportion of cannibalism (23.3%) in this stage. Adults consumed predominantly shrimp and fish. The use of food resources varied significantly between development stages (ANOSIM; r = 0.458; p<0.005), showing changes in food preferences during ontogeny. The Similarity Percentage Analysis (SIMPER) indicated that Cladocera and Copepoda were responsible for the differences observed between the larval stages of pre-flexion, flexion and post-flexion. M. amazonicum and Chironomidae were responsible for the differences between juvenile and larval stages, while M. amazonicum and other fishes caused the differences between adults and other ontogenetic stages. These results are confirmed by the relationship between standard length and developmental periods (ANCOVA; r² = 0.94; p<0.0001). In general, there were low values of trophic niche breadth. The essentially carnivorous habit from the early stages of P. squamosissimus and the predominant use of M. amazonicum by adults have important roles in feeding patterns of the species, suggesting a major contribution to its success and establishment, especially in lentic environments.     

Paracoccidioidomycosis in wild monkeys from Paraná State, Brazil

The aim of this study was to evaluate the seroprevalence of Paracoccidioides brasiliensis infection in wild New World monkeys (Cebus sp. and Alouatta caraya). A total of 93 animals (Cebus sp., n = 68 and Alouatta caraya, n = 25) were captured in the Paraná River basin, Paraná State, Brazil and the serum samples were analyzed by ELISA and immunodiffusion using P. brasiliensis gp43 and exoantigen as antigens, respectively. The seropositivity observed by ELISA was 44.1% and 60% for Cebus sp. and A. caraya, respectively, while by immunodiffusion test Cebus sp. showed positivity of 2.9% only. No significant difference was observed in relation to age and sex. This is the first report of paracoccidioidomycosis in wild capuchin monkeys and in wild-black and golden-howler monkeys. The high positivity to P. brasiliensis infection in both species evaluated in our study and the positivity by immunodiffusion test in Cebus sp. suggest that natural disease may be occurring in wild monkeys living in paracoccidioidomycosis endemic areas.     

Fish diversity and community structure in two small tributaries of the Paraná River,Paraná State,Brazil

In eleven sites on two small tributaries of the Paraná River (North-West Paraná State), 6.8 and 4.0 km in length, 1263 fish specimens of 28 taxons and 14 families were collected using electrofishing. Up to twelve years ago the catchments of the two rivers were covered by tropical jungle; this has now been replaced by pasture and arable fields. Mean diversity indices of Simpson and Shannon indices were close to 0.6, which would indicate that human impact affected fish populations although the river beds have retained their original shape, except cleared of riparian trees. Despite their close location (about 18 km), the two streams differed from each other in their fish faunal composition. The distinctive nature of the fish communities in the two streams was a result of: conductivity, pH, also hiding places, riparian vegetation, submerged macrophytes and depth and width of the rivers.     

Diversity and Abundance of the Planktonic Rotifers in Different Environments of the Upper Paraná River Floodplain (Paraná State – Mato Grosso do Sul State,Brazil)

This study proposes that diversity and abundance of rotifers show spatial and temporal variations in the Upper Paraná River floodplain due to heterogeneity of the environment and hydrological level fluctuations of the main river. The structure and dynamics of rotifer assemblages were investigated by samplings carried out during the rainy (February) and dry period (August) of the year 2000, in 36 environments (rivers, channels, backwaters, open and isolated floodplain lakes). The influence of phytoplankton biomass on rotifer diversity and abundance was also investigated. 104 taxa of rotifers were identified. The highest species richness was found in rivers and open floodplain lakes, the highest abundances in the isolated floodplain lakes, and the highest values of species diversity in the channels, especially during the rainy period. β₂-diversity values were higher in the channels, especially during the dry period. Flow differences and food availability were predominant factors influencing the structure and dynamics of the rotifer communities.     

Petunia guarapuavensis (Solanaceae): A new species from planalto of Paraná and Santa Catarina,Brazil

Petunia guarapuavensis, a new species fromplanalto (high plateau) of Paraná and Santa Catarina in Brazil, is described, and its morphological distinction from related species, features of the habitats, and geographical distribution are discussed.