• Partição de recursos entre seis espécies de Loricariidae no alto rio Paraná, na região de Guaíra-Pr : distribuição espacial, morfologia e ecologia trófica.

      Delariva, Rosilene Luciana (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 1997)
      This study were approached the spatial distribution, morphology and feeding ecology of six species of Loricariidae during the period August 1996-April 1997, in an area approximately 4 Km, at the Paraná River, including the upper portion of former Sete Quedas waterfalls. For the analysis of spatial distribution, the fishes were catched with castnets commercial fishery from 17 to 22 April 1997. The morphology, biometry and feeding information's were obtained of the fishes captured monthly from August 1996 to April 1997, using the same fishery strategy. Multivariate analyses (Cluster Analysis, Dentrended Correspondence Analysis) were used to examine the similarity patterns of different attributes (distribution, morphology and feeding) among the species. The spatial distribution was related with difference in the substrate type and depth. R. aspera and H. ternetzi showed preference for heterogenic bottom and deeper environments. H. regani and H. margaritifer distributed in shallower areas independent of substrate type, and M. Aculeatus e H. microstomus were more abundant in shallower areas with homogeneous substrate. In general, the six species showed two forms of food intake, for sucking (R. aspera) and browsing (the others). These feeding tactics were related with the differences morphological characters of the feeding apparatus. R. aspera has a morphology adapted to the consumption of high quantity of organic detritus as well as high length gut and gills rakers well developed while that others explore aufuwchs using their cuspited and in scoop form teethes. High value of feeding overlap were registered just among M. aculeatus X H. microstomus and R. aspera X A. regani. For the others congenerics species the value were under of 50.0. So, the feeding specialization as well as the spatial segregation's must represent important role in the separation of the trophic niche among these species avoiding high competitive pressure.
    • Variabilidade genética de Prochilodus lineatus (Characiformes, Prochilodontidae) na bacia do rio Paraná evidenciadas por marcadores moleculares.

      Revaldaves, Eloísa (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2001)
      Overfishing, pollution and construction of dams have impacted migratory fishes of Paraná River basin. Prochilodus lineatus is an economically important endemic migratory species from Platina basin. Decrease in P. lineatus landings have been observed as the need of management and conservation. This study aimed to investigate the genetic variability of this species through Random Amplified Polymorphic DNA (RAPD) and mtDNA sequencing techniques. The analyzed individuals were collected in the Paraná, Bahia, Corumbá and Miranda Rivers. A total of 1815 base pairs from 12 individuals were sequenced to seven PCRAmplified fragments representing five protein-coding mitochondrial genes. Estimates of percent nucleotide sequence divergence ranged from 0.00 to 0.95 and any geographic pattern to mtDNA haplotype distribution was observed. The RAPD study included 86 markers and 58 individuals and revealed a high level of polymorphism. Fisher?s exact test was computed to verify whether the genetic differences were significant for the total data and between geographically proximate population samples. The results suggest that Prochilodus lineatus is not genetically subdivided, although significant divergence in frequencies of some RAPD fragments was found. This information may have useful for stocking and management programs plannings of P. lineatus.
    • Variação espacial na estrutura das assembléias de peixes da planície de inundação do alto rio Paraná, Brasil.

      Petry, Ana Cristina (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2001)
      Spatial variation on fish assemblages structure of the upper Paraná River floodplain, Brazil. Although the upper Paraná River floodplain is subjected to impacts produced by hydroelectric plants upstream, fish assemblages studies acknowledge its importance in the maintenance of regional biodiversity. Fish assemblages of four categories of biotopes belonging to three subsystems were analyzed. The aim was analyse the spatial variation in the structure and to identify processes responsable to species composition and abundance. Quarterly samples were carried out with gill nets in 19 sites during the year 2000. The sites comprised rivers, channels, connected and disconnected lagoons in the subsystem Paraná and two tributaries, the Baía and Ivinheima Rivers. Connected lagoons showed greater species richness and similar species composition. There were not detected significant differences in diversity and in eveness among categories of biotopes and subsystems. Dominance pattern is achieved by species whose life strategies allow to take advantages of the intensity, duration and frequency changes of the flood pulses. Biotic (predation) and abiotic (local processes) factors explained satisfactorily the assemblages structure.
    • Ecologia trófica da ictiofauna do rio Iguaçu-Pr sob efeitos do represamento de Salto Caxias.

      Delariva, Rosilene Luciana (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2002)
      This study were approached the spatial distribution, morphology and feeding ecology of six species of Loricariidae during the period August 1996-April 1997, in an area approximately 4 Km, at the Paraná River, including the upper portion of former Sete Quedas waterfalls. For the analysis of spatial distribution, the fishes were catched with castnets commercial fishery from 17 to 22 April 1997. The morphology, biometry and feeding information's were obtained of the fishes captured monthly from August 1996 to April 1997, using the same fishery strategy. Multivariat analyses (Cluster Analysis, Dentrended Correspondence Analysis) were used to examine the similarity patterns of different attributes (distribution, morphology and feedings) among the species The spatial distribution was related with difference in the substrate type and depth. R. aspera and H ternetzi showed preference for heterogenic bottom and deeper environments. H. regani and H. margaritifer distributed in shallower areas independent of substrate type, and M. aculeatus e H. microstomus were more abundant in shallower areas with homogeneous substrate. In general, the six species showed two forms of food intake for sucking (R. aspera) and browsing (the other). These feeding tactics were related with the differences morphological characters of the feeding apparatus. R. aspera has a morphology adapted to the consumption of high quantity of organic detritus as well as high length gut and gills rakers well developed while that others explore aufuwchs using their cuspited and in scoop form teethes. High value of feeding overlap were registered just among M acu1eatus X H. microstomus and R. aspera X H. regani. For the others congenerics species the value were under of 50,0. So, the feeding specialization as well as the spatial segregation's must represent important role in the separation of the trophic niche among these species avoiding high competitive pressure.
    • Redes de interações tróficas no reservatório de Segredo e um tributário do rio Iguaçu, bacia do rio Iguaçu, Paraná, Brasil (1994-1996).

      Abes, Sara da Silva (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2003)
      Two trophic steady state models (second and third periods) were elaborated for the Segredo Reservoir and the Iratim River, using the Ecopath II software. Segredo Reservoir, the second of a cascade of four reservoirs in the Iguaçu River, was closed in 1992. Iratim River is the largest tributary of the Segredo Reservoir. The diagram flows of the Segredo Reservoir show two trophic groups of the fish (carcinófagos and malacófagos) that are not included in models of the Iratim River. Among other features of food webs, the summary of statistics showed that Segredo Reservoir is a system of intermediary development, which should be reaching a level of stability. Moreover, the Iratim River may be classified as relatively developed and mature system. The detritus (from the drowning of the vegetation) seem to key to the flow of energy in the reservoir trophic networks, in their first years after impoundment, supporting the trophic structure of the ecosystem. The detritus seems to exert similar function in the Iratim River. However, specific studies are needed on the autochthonous and allochthonous detritus. Future projects for the prediction of effects of management strategies for these areas altered by impoundment, should include simulations, requiring a series of static models for this purpose. These models should include the tributary connected to these dam areas.
    • Estudo da relação entre a comunidade parasitária, meio ambiente e dinâmica da população de Prochilodus lineatus (Valenciennes, 1836) e Astyanax altiparanae Garutti & Britski, 2000, na planície de inundação do alto rio Paraná, Brasil.

      Perez Lizama, Maria de los Angeles (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2003)
      One hundred and forty-nine fish were collected in the high Paraná river floodplain, Brazil, of these 121 (82.1%) were parasited. Thirty-three species of metazoan parasite specie were recorded. Only Rhinonastes pseudocapsaloideum was classified as secondary, while that the other species were classified like satellites. The metazoan parasite community of P. lineatus show the typical pattern of distribution overdisperse. The pair of species of ectoparasite Ergasilus sp.-Tereancistrum curimba n. sp. showed associated positively, being theirs abundance also positively correlated. Among the endoparasites, the pair Saccocoelioides magnorchis-S. nanii presented positively associated and with the abundance positively correlated. The mean diversity in the infracommunities of P. lineatus was H= 0.6875 ± 0.4398. Regarding the richness of species from the community, had the predominance of 4 species by host. The standard length of the host did not present correlated with the diversity (rs = 0.1726; p = 0.0533). The monogenean T. curimba n. sp. and Kritskya boegeri, and the digenean S. magnorchis and S. nanii presented significant correlation between the standard length and the abundance of parasitism. Correlation between the age of the fish and to prevalence was not observed. The species Amplexibranchius sp, K. boegeri and S. magnorchis presented significant differences in the parasite abundance according to the age class of the hosts. For Amplexibranchius sp., the class more intensely parasited was 3 years. Already for K. boegeri the intermediate age classes 3, 4 and 5 years went the more parasited. Only Tereancistrum curimba n. sp. showed significant difference in the prevalence between hosts male and female where the female presented themselves more parasited. It was not observed significant difference from the abundance of parasitism between the sexes of the hosts.
    • Ecologia de insetos aquáticos associados a Eichhornia azurea (Schwartz) Kunth em uma lagoa de várzea na planície de inundação do alto rio Paraná.

      Franco, Gilza Maria de Souza (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2003)
      This paper deals with the ecology of aquatic insects in phytophylous Eichhornia azurea, addressing aspects of taxonomic composition, abiotic and biotic influences and also the analysis of the trophic structure of the community. To carry out this research were conducted quarterly collections from February to November 2000 aquatic insects associated with E. azurea in the coastal region of the closed lagoon, the Upper Paraná River floodplain. Some steps were taken of environmental variables for the verification of their possible influence on the seasonal fluctuation of density, diversity and diet fitófila entomofauna. In laboratory insects have been identified, quantified and analyzed their diets, those based on the content of the digestive tract. The entomofauna investigated showed high density, diversity and richness, with 9,203 individuals belonging to Ephemeroptera orders Odonata, Trichoptera, Lepidoptera, Coleoptera and Diptera. The most abundant and more wealth was the Diptera Chironomidae family, represented mainly by Polypedilum (Asheum) Polypedilum sp., Chironomus, Goeldichironomus serratus. The highest total density was observed in winter (4,903 ind / 100g PS) when it was found the higher dissolved oxygen content and high primary production of algae. The lower density was in the summer (194 ind / 100g OS). This season was characterized by the low amount of oxygen, high temperature and low concentration of chlorophyll?. In general, the seasonal fluctuation of insects studied was influenced mainly by temperature, dissolved oxygen, pH and periphyton biomass. The diet fitófila entomofauna was well diversified, but with dominance Collectors Guild. Predators and shredders showed low density and abundance relative to other functional groups. The composition of the diet as well as the variation of the density and richness of functional groups were determined mainly by the availability of food resources, which are regulated by environmental factors such as temperature, dissolved oxygen and nutrients.
    • Moluscos da planície de inundação do alto rio Paraná (Brasil) e a potencialidade como primeiros hospedeiros intermediários de digenéticos.

      Souza, Geza Thais Rangel e (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2004)
      This paper reports the distribution and seasonality of the species of snails intermediate hosts of digenean trematodes, and provides information about the possible infections of diplostomidae in this community, in lentic environments in the flood plain of the High Parana River. They were collected and analyzed 10 species of molluscs, which only Biomphalaria pelegrina was characterized as a potential host for Diplostomidae. There was clear seasonality in the density and abundance of shellfish, correlated significantly with the water temperature, and the highest values were observed between the months of November 2002 to February 2003. Found 32 cercariae of Hysteromorpha triloba in March 2003.
    • Evolução morfológica do arquipélago Floresta Japonesa no alto rio Paraná.

      Correa, Geraldo Terceiro (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2004)
      This work presents besides cartographic material, quantitative data about the marginal erosion as also the differences of the geomorphic features that occured at the multichannel segment of the high Paraná river. From historical sources of photographic material existing in the region, were studied the difference between transformations expressed in the fluvial channel in the years of 1952, 1965, 1970, 1980 and 1996. In this respective years, it was observed that the Japanese Forest Archipelago presents erosive-depositional behavior similar to two other great archipelago located on its upstream, the Carioca and the Mutum Porto Rico. The marginal erosion was accompanied between the years 1999 and 2001 and the results showed up that not only the granulometric constituents were responsible for the erosion rates but also the average flow speed.
    • A traíra Hoplias aff. malabaricus (Bloch, 1794) na planície de inundação do alto rio Paraná : influência sobre as assembléias de peixes e aspectos da auto-ecologia.

      Petry, Ana Cristina (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      This study tested experimentally the hypothesis that traíra Hoplias aff. malabaricus is a keystone predator in isolated lagoons of the upper Paraná River floodplain. The experiment was conducted from April to October 2002, through an initial manipulation of traíra density (levels of treatment: addition, removal and reference). Treatment effects were evaluated on descriptors of fish assemblage structure (species richness, abundance, equitability and biomass), through repeated measures analysis of variance, in two habitat categories (open and macrophyte-dominated areas). In spite of being recorded in all assemblages and depended on habitat category, reductions in species richness were significantly more pronounced in lagoons where H. aff. malabaricus was removed. In these lagoons, the number of individuals was also significantly lower than in those where the piscivore was added or maintained in natural densities. Equitability showed opposite tendencies. Analysis of relative abundance by size-classes revealed a sharp reduction in the number of small-sized individuals (< 3cm), contributing to the absence of pronounced alterations in biomass. These evidences supported our hypothesis and demonstrated that the understanding of mechanisms by which predators affect the persistence of prey species constitutes a challenge for future researches, especially in tropical ecosystems, in which phytoplankton changes in Paraná River were verified, in function of the formation of Porto Primavera Reservoir and the climatic alterations that occurred during the period studied (1993-1994 and 2000-2005), especially those related to El Niño and La Niña phenomena. In the second chapter entitled "Interannual variation of phytoplankton in a river-flooding lake system (Upper Paraná River, Brazil)", we verified that the alterations of phytoplankton structure in Patos Lagoon and Ivinhema and Paraná rivers were associated to the fluctuations of hydrosedimentological regime of Ivinhema and Paraná rivers, probably, influenced by the phases La Niña (2000-2001) and El Niño (2003-2004) Southern Oscillation cycle (ENSO).
    • Oligochaeta aquáticos em diferentes ambientes da planície aluvial do alto rio Paraná.

      Fujita, Daniele Sayuri (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      In the upper Paraná River plain, the distribution of benthic organisms is directly affected by the variation in the flow of the main channel and geomorphological aspects that influence the physical and chemical characteristics of the environment. Oligochaeta is one of the most abundant zoobênticos groups of the upper Paraná River plain, and recorded in different environments that plain. The samples were collected every three months between February 2000 and November 2002 in different types of environments Ivinhema and Parana rivers. In lotic, it was found higher percentages of sandy sediment, ponds, mud percentages and higher organic matter, especially lakes without communication. These studies were analyzed 10,250 individuals Oligochaeta. Through the indicator value analysis (IndVal) allowed the classification indicator species from different environments: Haplotaxis aedochaeta as indicator species of the main channel Ivinhema, Narapa bonettoi for the primary and secondary channels, while for ponds with communication and without communication direct with Ivinhema, indicator species were Pristina osborni and Branchiura sowerbyi respectively. The dynamic factors of the water flow and the degree of connectivity of the lakes with the main channel, influenced the composition and abundance of Oligochaeta. Temporal variations in density and dominance of species of Oligochaeta of the Parana River, seem to be controlling the impact of the consequences of the hydrological regime of the river, exercised by dams located upstream. These results underscore the need for specific knowledge of Oligochaeta in benthic macroinvertebrate studies because they are good indicators of specific environments and environmental change.
    • Fatores que determinam o comprimento da cadeia alimentar em reservatórios neotropicais : uso dos isótopos estáveis de ¹³C e ¹5N.

      Pereira, Alexandre Leandro (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      Studies focusing on the energy flow in ecosystems has been the concern of many environmentalists in recent decades. Among the most widely discussed issues stand out from those who seek to identify the factors that determine the length of the food chain in neotropical reservoirs. In this sense, analyzing the isotope ratio of nitrogen (δ¹5N) and carbon (δ¹³C) of piscivorous fish and primary producers in six of Paraná reservoirs aimed to identify the factors that drive the variation in the length of the food chain. Associated with these indicators factors, investigated whether it still environment stability of effect on omnivorism and its potential less productive environments. Therefore, quarterly samplings from February to December 2002 were held in the reservoirs Parigot Governor Souza, Irai, Santo do Vau, Secret, Mourao and Rosana. In these environments, the length of the food chain did not correlate significantly with the availability of resources, reservoir area and integration-productivity area. However, the stability of the ecosystem, measured by its capacity development (overhead) (%) showed non-linear correlation (R = 0.90), and environments with intermediate development capability values ​​had the largest chain lengths. The omnivorous species, G. brasiliensis showed lower trophic position in more stable environments, and the degree reservoir productivity did not influence the isotopic differentiation of trophic levels.
    • Tática reprodutiva e estrutura da população de Cichla monoculus Spix & Agassiz, 1831 (Perciformes, Cichlidae) em ambientes com diferentes regimes hidrológicos.

      Espinola, Luis Alberto (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      This study assumed that some species are able to change the reproductive tactic depending on currently environmental conditions. The tested hypothesis is that the peacock bass Cichla monoculus, an introduced species of Amazonian region, presents a differential reproductive tactic that depends on the variation of the hydrometric level on the upper Paraná River floodplain and Corumbá Reservoir. The hydrological analysis showed that the level on the floodplain was very irregular compared to the level on the reservoir, presenting often potamophases. Limnophases were less frequent and of long duration. Because of the short retention time, hydrometric level variations on reservoir were of less than 9 cm above and below the overflow level, with the same number of potamophases and limnophases, both of them of similar duration. Either in the floodplain as in the reservoir, abundance peaks of juveniles occurred on potamophases. In the floodplain, these peaks were associated to sharp increase of short duration of the hydrometric level, especially in February 2000 and March 2003. In the reservoir, the occurrence of juveniles was registered practically in all samplings, with two peaks in April and December 1998, corresponding to the rainfall period. In both systems, juvenile abundance was positively correlated with the hydrometric level. It was concluded that C. monoculus changes its reproductive tactic responding to variations of hydrometric level and environmental seasonality.
    • Estrutura da assembléia de cladóceros em reservatórios nos Estados de São Paulo e Paraná : riqueza, diversidade β e abundância.

      Santos, Francini Vila dos (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      The main aim of this study was to evaluate the spatial and temporal patterns of richness, β diversity species and abundance, in six reservoirs located at Paraná State (Iraí, Parigot de Souza, Segredo, Mourão and Salto do Vau reservoirs) and São Paulo State (Rosana reservoir). We supposed that these attributes of the assemblage were higher in the transition region of the eutrophic reservoirs in the rain season. Cladocerans were sampled each three months, at subsurface, in mixing zone and in the deepest layer of water column, in three reservoir regions (fluvial, transition and lacustrine regions), from March to November 2002. Higher values of species richness were registered in the Mourão reservoir and lower values in the Salto do Vau reservoir (oligotrophics). There were no significant differences for species richness among the regions and hydrological periods. For b diversity, we found higher values in the Salto do Vau reservoir and lower values in the Segredo reservoir (mesotrophic). There was no a single pattern for β diversity according to the regions, but there was a temporal pattern that showed higher values in the dry season. The β diversity was significantly different among the reservoirs. The higher abundance was registered in Iraí and Parigot de Souza reservoirs (eutrophics). Significant differences were verified among the reservoirs according the trophic status. In general, the higher abundance was observed in the lentic regions of the reservoirs (transition and lacustrine regions). Temporally, we found significant differences between the periods, with higher values in the dry season. The results were different from the hypothesis. In general, we suggest that the cladoceran assemblage was structured according to the influence of the hydrodynamic and depth of the reservoirs to the richness and the β diversity, and according to the trophic status to the species dominance and abundance.
    • Chironomidae em diferentes ambientes da bacia do rio Ivinhema, planície de inundação do alto rio Paraná, MS.

      Butakka, Cristina Márcia de Menezes (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      The first chapter of this work have objective to characterize the Chironomidae fauna in the basin of the Ivinhema River, in the main channel, in the secondary channel, in five lakes connected and in five lakes without connection and to analyze the numerical density, biomass, diversity and dominance of the larvae. Of the 68 taxa, Aedokritus sp., Tanytarsus sp., Chironomus gr. decorus sp. I and Procladius sp.1 were found in all sampling sites. Chironomus gr. decorus sp.1 contributed with the greatest biomass values in the central region of lakes without connection, whereas Aedokritus sp. dominated in the littoral region of lakes. The greater values of diversity indices of Chironomidae in the littoral region of channels whereas the dominance indices were greater on the central region of theses environments. In the second chapter was analyzed the diet of Chironomid larvae and calculated the relative abundance of dietary items using the area taken in the digestive content Chironomid larvae. The categories recorded were algae, organic detritus (fragments of algae, of plants and animals), mineral detritus (sponge spicules), and fungi spores. The most common algae were those of the class Bacillariophyceae (Aulacoseira granulata, Pinnularia sp.1, Fragilaria sp.1, Gomphonema gracile; Gomphonema parvulum, Navicula cf. constans, Eunotia bidens and Cymbella sp.1) and those of the class Euglenophyceae (Trachelomonas sp.2). The majority in the larvae appeared to be opportunistic and omnivore, feeding non-selectively from the available sources in each type of habitat. In the chapter III, was carried a study to analyze the niche overlap between trophic groups of Chironomid larvae in different types of environments. The greatest number of trophic niche overlaps was found between collectors-gatherers (Aedokritus sp., Chironomus gr. decorus I, Goeldichironomus neopictus) and other trophic groups in the connected lakes. In the chapter IV, to of examine the emergence of Chironomidae in the different habitats of the Patos Lake, were utilized traps of surface emergence (floating) for a period of 48 ±2 hours, obtaining quantitative data for richness and abundance. The taxons identified in the specific level were: Goeldichironomus neopictus, G. petiolicola, G. maculatus, Tanytarsus ligulatus, Parachironomus atroari, P. guarani e P. cayapo. The higher abundances were of Polypedilum (Tripodura) sp.1 and Tanytarsus ligulatus, specially in the littoral region. The spatial variation leads to the assumption that the attributes of the Chironomidae fauna vary with the diversity and quantity of habitats of the lakes, channels and rivers in the floodplain of the Upper Paraná River.
    • Fatores determinantes da distribuição de plantas submersas e dos atributos das assembléias de macrófitas aquáticas no reservatório de Rosana.

      Pierini, Sandra Andréa (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      The effects of underwater radiation, represented by different depths (0.5 and 1.0m) and the effects of stands colonized by E. najas and E. densa upon the growth rates of shoots and roots, stem number and length and ratio root:shoots of these species were assessed in field experiments in the Rosana Reservoir. Differences in the measurements were not significant when species grew at 0.5 and 1.0m, indicating that these two underwater radiation levels did not affect the measured attributes. Nevertheless, there were significant differences between species and the results for all attributes were higher for E. najas than E. densa. The effect of stands showed significant differences for shoot:root ratios, root growth rates and number of branches. The interaction between species branches number and stands were also significant. E. najas showed lower value of the shoot:root ratios when growing inside stands of E. densa. It is probably a response to maximize the use of underwater radiation. On the other hand, E. densa increased allocation of biomass to roots, probably to maximize nutrient uptake. Despite different strategies, the values of all attributes were greater in E. najas than E. densa, mainly when the first species grew inside stands of its own species. Based upon these results, we suppose that E. najas is a more efficient competitor when both colonize simultaneously the same habitat.
    • Estudos ecológicos dos ciconiiformes (aves) nos hábitats de forrageamento da planície alagável do alto rio Paraná, Brasil.

      Gimenes, Márcio Rodrigo (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2005)
      Cap.1. The structure and composition of Ciconiiformes community in the foraging habitats on the floodplain of the upper river Paraná, Brazil, as well as the possible seasonal variations in the selection of these habitats for each species and the seasonal population fluctuations of the species in the studied habitats were analyzed. Four foraging habitats were considered: rivers, channels, connected lagoons and disconnected lagoons. Data on prey availability (fish) in the foraging habitats along the sampling period were obtained. Quarterly samplings of Ciconiiformes were conducted in 2002 and 2003, by foot or by boat. A total of 15 species of Ciconiiformes was registered in the area, and connected lagoons presented the highest species number and highest abundance for most species. Egretta thula, Mycteria americana, Platalea ajaja and Jabiru mycteria were the species more dependent on high-quality patches, because they frequently selected connected lagoons (habitat with highest prey availability) and abandoned the area during flood. Ardea cocoi, Ardea alba and Tigrisoma lineatum were not so dependent on highquality patches, using habitats with lower prey availability and they did not abandon totally the area during flood. Variations in the foraging techniques and social behavior explain that difference between the two groups. Besides a considerable species number, the study area can have special importance as feeding place for the Pantanal populations of M. americana and P. ajaja during migration to Argentina and Rio Grande do Sul. Management strategies that maintain the hydrologic regime more similar possible to the natural are necessary in order to promote an enhancement of the area as foraging place for Ciconiiformes.
    • Influência da construção da hidrelétrica do rio Jordão sobre a ictiofauna : impactos e colonização.

      Luiz, Elaine Antoniassi (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2006)
      Alterations prompted by the filling of Jordão Reservoir, located in the Jordão River, a tributary of the Iguaçu River, on the fish assemblage were evaluated. Captures were performed with gillnets (before and after reservoir filling; periods Pre, Pos 1 and Pos 2) with different mesh sizes. Four stations, previously selected considering the reservoir filling, were sampled. Abundance was indexed by catch per unit of effort (CPUE), that was used to evaluate spatial and temporal variations in demography, to measure some attributes (species richness, evenness and Shannon Diversity Index), and to describe composition and structure of fish assemblages as well (summarized in a detrended correspondence analysis - DCA). The endemism was considerable high (72.5% of the fish fauna). Most of the captured species was small to middle sized, mainly belonging to the orders Characiformes and Siluriformes. After the first year of filling (Pos 1), mean species richness increased in all sampling stations, with slightly lower values in the following year (Pos 2), except in the station located upstream from the reservoir. Evenness and Shannon Index decreased after reservoir filling. Composition and structure of the species varied among periods (Pre, Pos 1 and Pos 2), in all stations located above the dam. The most conspicuous change in the fish assemblage was verified in its structure (both spatial and temporal) instead in its composition (few species disappeared). Therefore, studies conducted before and after reservoir filling are fundamental, especially in low order rivers with high endemism. In addition, studies have to encompass adequate temporal and spatial scales, to allow a more precise identification of impacts resulted from reservoir filling.
    • Ovos de resistência de cladóceros e sua contribuição para a diversidade específica do zooplâncton em uma lagoa da planície de inundação do alto rio Paraná.

      Palazzo, Fabiana (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2006)
      Zooplankton produces resting eggs and diapause stages as strategies to promote its survival in the environment during periods of adverse conditions, and consequently allow the community diversity. The main aim of this study is to investigate these eggs contribution, presents in the bottom from an isolated lagoon in the upper Paraná river floodplain, for cladoceran diversity. We predict that species proceeding from eggs hatching do not occur in the plankton of the lagoon. Bottom samples were collected at six sampling sites in the Osmar lagoon banks, in September 2004 and June, July, August and September 2005, using a corer sampler. Zooplankton samplings were carried out in the pelagic region using a motorized pump (1000 L) and plankton net (68 µm). At the same time, pH, water temperature (°C), electric conductivity (µS.cm-1) and dissolved oxygen (mg.L-1) were measured. In laboratory, the resting eggs were counted, photographed and stored in individuals plastic flasks, containing distilled water and maintained under constant temperature (25 ± 2°C) and photoperiod (12 h). Resting eggs were examined daily until hatching. Higher abundances of these eggs were observed in July, when lower values of temperature and electric conductivity and higher values of dissolved oxygen and pH were verified. ANOVA results showed that the abundance mean was significantly different among months. From resting eggs, Ceriodaphnia reticulata, Macrothrix spinosa, Ilyocryptus spinifer, Ephemeroporus tridentatus and Diaphanosoma sp. hatched out although they were not registered in the plankton samples. C. reticulata was registered in the first time on this floodplain. These results corroborated the hypothesis that resting eggs contribute for zooplankton diversity in the lagoon.
    • Alimentação e análise morfológica de quatro espécies de peixes (Astyanax altiparanae, Parauchenipterus galeatus, Serrasalmus marginatus e Hoplias aff. malabaricus) na planície de inundação do alto rio Paraná, Brasil.

      Peretti, Danielle (Universidade Estadual de Maringá. Departamento de Biologia. Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais., 2006)
      The species was set in two trophic guilds - insectivores (Astyanax altiparanae Garutti & Britski, 2000, Parauchenipterus galeatus (Linnaeus, 1766) and piscivores (Serrasalmus marginatus Valenciennes, 1847 and Hoplias aff. malabaricus (Bloch, 1794). The first two, although consumers of insects, explored different alimentary groups, standing out the Hymenoptera to A. altiparanae and Coleoptera to P. galeatus. Serrasalmus marginatus and H. aff. malabaricus consumed mainly fishes, however just pieces of preys were more often found in the first specie stomach content and whole fishes in the second one. The morphology of the digestive tract was important to do inferences as how the predators obtain and use food resources. Astyanax altiparanae exhibited characteristics that allowed it to obtain food in several compartments of the water column according to mouth position and the type of food explored associated with characteristics as teeth, gill rakers and pyloric cecum. Also P. galeatus consumed food resources that are available in all aquatic compartments, however the characteristics to capture, to manipulate and to absorb food differed, being evidenced the importance of teeth plates and pharyngeal teeth. Serrasalmus marginatus and H. aff. malabaricus although resembling each other in many aspects of the digestive tract morphology they differed in the strategies to capture preys. It still stands out, as one of the several mechanisms to avoid the prey escape when already inside the digestive tract structures, the presence of striated muscle in the initial portion of the H. aff. malabaricus stomach.