Iguatemi River Research Articles

Ichthyofauna from three streams of the lower Iguatemi River in the upper Paraná river basin, Brazil

The ichthyofauna from 3 streams (Água Boa, Perobão, and Santa Maria) to the lower Iguatemi River were inventoried, which is located in the upper Paraná river basin, in Mato Grosso do Sul state, Brazil. Sites in the upper, intermediate, and lower portions of each stream were quarterly electrofished from March to December 2008. All sampled fish (n = 6,816 individuals) represented 43 species of 5 orders, and 16 families. The most abundant species was Phalloceros harpagos (63.5%), followed by Astyanax aff. paranae (10.6%), Hypostomus ancistroides (5.9%), Gymnotus inaequilabiatus (3.4%), and Knodus moenkhausii (2.7%). Despite the high ichthyofauna richness in the lower portion of Iguatemi River, the need to implement and/or expand soil conservation practices and riparian forest restoration is of utmost importance to maintain these populations in the long term.

<b>Immature Odonata-Anisoptera in the Iguatemi river basin, upper Paraná River, Mato Grosso do Sul State, Brazil

This study present an inventory of the genera of Odonata-Anisoptera in lotic environments of the Iguatemi River basin, upper Paraná River, Mato Grosso do Sul State, Brazil. Samplings were performed from December 2006 to February 2009 in the Iguatemi River and eight streams of the basin. We collected 739 immature Odonata, distributed in 25 genera and three families; of which one genus represent a new record for the Mato Grosso do Sul State. Progomphus, Tramea, Elasmotemis, Macrothemis, Aphyla and Phylocycla were the most representative genera in the Iguatemi River basin. The genus accumulation curve predicts an increase of new genera for the Iguatemi River basin.

<b>Fish trophic structure in a first order stream of the Iguatemi River basin, Upper Paraná River, Brazil

We described the spatial distribution of fish trophic groups in the Agua Boa Stream, MS, Brazil. Specimens were caught using electrofishing in the upper, intermediate and lower stretches of the stream, between March and November 2008. We analyzed 415 stomach contents of 24 species. Detritus/sediment and aquatic invertebrates were the main exploited resources. Ordination analysis categorized the species in six trophic groups. Aquatic invertivores showed the highest richness (10 species), followed by detritivores (08 species), omnivores (03 species), terrestrial invertivores (03 species), algivores (02 species) and herbivore (01 species). Three trophic groups occurred in the upper stretch, six in the intermediate and five in the lower. Detritivores, omnivores and algivores showed the highest density, while detritivores and aquatic invertivores presented the highest biomass. Autochthonous resources were particularly important to the studied fish fauna, especially aquatic invertebrates, so, conservation actions reducing the simplification of the habitat by silting and recovering the riparian forest are essential to maintain the ichthyofauna of the Agua Boa Stream.

Assemblage of immature Odonata (Insecta, Anisoptera) in streams of the Mato Grosso do Sul State: spatial implications

ABSTRACT This study investigated the assemblages attributes (composition, abundance, richness, diversity and evenness) and the most representative genera of Odonata, Anisoptera at Água Boa and Perobão Streams, Iguatemi River basin, Brazil. Both are first order streams with similar length that are impacted by riparian forest removal and silting. Quarterly samplings were conducted from March to December 2008 in the upper, intermediate and lower stretch of each stream. The Mantel test was used to check the influence of spatial autocorrelation on the Odonata composition. Spatial variations in the composition were summarized by the Principal Coordinates Analysis (PCoA) using Mantel test residuals. The effects of spatial correlation on richness and abundance were investigated by the spatial correlogram of Moranʼs I coefficients. The most representative genera in each stream were identified by the Indicator Value Method. The spatial variations in the attributes of the assemblages were assessed using analysis of variance of null models. We collected 500 immature individuals of 23 genera and three families. Among the attributes analyzed only the composition and abundance showed significant spatial differences, with the highest mean abundance found in the Perobão Stream. Miathyria and Zenithoptera were the indicator genera of the Água Boa Stream and Erythrodiplax, Libellula, Macrothemis, Progomphus and Tramea were the indicator genera of the Perobão Stream.

Cytogenetic analysis of two locariid species (Teleostei, Siluriformes) from Iguatemi River (Parana River drainage) in Brazil.

Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters. In this study, were cytogenetically examined two species of Loricariidae (Pterygoplichthys anisitsi Eigenmann & Kennedy, 1903 and Farlowella amazonum (Günther, 1864) belonging to Hypostominae and Loricariinae subfamilies respectively) from Iguatemi River. Our study provide the first description regarding C-band and fluorochromic analysis in Farlowella amazonum. In Farlowella amazonum, diploid number was 58 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric regions of some chromosomes and large subtelomeric blocks were evidenced on the long arm of the pair 27, being this region CMA3+/DAPI-. The Pterygoplichthys anisitsi showed diploid number equal 52 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric and telomeric regions of some chromosomes and conspicuous large telomeric blocks on the long arm of the pair 10, being this region CMA3+/DAPI-. The results show that karyotype formula is nonconservative in Pterygoplichthys anisitsi and Farlowella amazonum.

Length-weight relationships for 55 freshwater fish species from the Iguatemi River, Upper Paraná River basin, Brazil

Summary This study reports the length-weight relationship estimatives (LWRs) for 55 fish species caught in the Iguatemi River drainage, Upper Parana River Basin, Mato Grosso do Sul State, Brazil. The LWRs of 15 of the species are provided for the first time.

Cytogenetic and morphometric analysis in the species Astyanax altiparanae Garutti & Britski, 2000 (Teleostei, Characidae) from the Iguatemi River Basin, Brazil.

The genus Astyanax is relatively common and encompasses various similar taxa forming a highly complex group that is difficult to precisely delimit. The present study aims to analyze cytogenetically and morphologically specimens of A. altiparanae belonging to distinct populations of the Iguatemi River Basin, Mato Grosso do Sul State, Brazil, for a better understanding of the evolutionary processes in this fish group. This study analysed 32 specimens of Astyanax altiparanae from Iguatemi River basin, MS, Brazil: 24 from the Agua Boa stream and 8 from the Santa Maria stream. All specimens showed a diploid number equal to 50 chromosomes with differences in the karyotypic formula and types of chromosomes bearing the NOR between the two localities. The constitutive heterochromatin showed interstitial markings evident in the region of some chromosomes in both populations. In the morphometric analysis, the first three axes were retained for interpretation which together explained 81% of variance, showing morphometric distinction between populations. Chromosomal and morphometric data obtained may be useful for taxonomic and phylogenetic studies in this group of fish.

New records and checklist of aquatic and semi-aquatic Heteroptera (Insecta: Hemiptera: Gerromorpha and Nepomorpha) from the Southern region of Mato Grosso do Sul, Brazil

A list of aquatic and semi-aquatic Heteroptera species from the southern region of Mato Grosso do Sul State is presented. The material was collected between 2008 and 2009. Samples were obtained from 10 streams (Água Boa, Cerro Verde, Cumprida, Ponte, Doradão, Guaçú, Guaporites, Nhu-Verá, Perobão and Santa Maria), one river (Iguatemi River) and nine ponds (Bacal, Balan, Ponte, Cinco, Macrófitas, Bugão, Sítio, Cascalho, and Oxbow). A total of 63 aquatic and semi-aquatic species of Heteroptera were recorded, of which 32 are new records.

Cytogenetic Studies in Two Species of Genus<i> Pimelodella </i>(Teleostei, Siluriformes, Heptapteridae) from Iguatemi River Basin, Brazil

Cytogenetic Studies in Two Species of Genus<i> Pimelodella </i>(Teleostei, Siluriformes, Heptapteridae) from Iguatemi River Basin, Brazil

A conservationist approach on environmental diagnosis of ground use in the Iguatemi river basin, Mato Grosso do Sul State, Brazil

Landscape Ecology is a contemporary approach in conservation studies in which, coupled to the development and use of GIS-based tools, provides new methods for the analysis of forest fragments. Based on these new approaches, the environmental assessment of ground use in the Iguatemi river basin Mato Grosso do Sul State, Brazil is provided through conservation-based flora and ecology aspects. A regional map of ground use with field-collected data using Rapid Ecological Assessment methodology and digital satellite images was prepared. AER analysis showed a highly impacted region featuring intense transformation in ground use with a conversion of 87% of native forest into grazing and agriculture land. The general situation is inconsistent with APA guidelines, the conservationist unit which operates in the river basin. PPAs’ recovery, erosion control and adjustment to current environmental regulations are mandatory.

Participação da sociedade civil na gestão de unidades de conservação e seus efeitos na melhoria da qualidade ambiental da região Sudeste do Estado do Mato Grosso do Sul

Since the approval of Decree no. 4.340/2002 on the The National System of Conservation Units, several councils have been established with the participation of civil society throughout Brazil. The southeastern region of Mato Grosso do Sul comprises the “State Park of the River Ivinhema Margins” a total conservation and protection unit and an environmental protection area (EPA) of the Iguatemi river basin, a sustainable conservation unit comprising nine municipalities. The Park has a Management Council and EPA has municipal councils which are all involved in the areas management. Current research analyzed questionnaires forwarded to the 141 council members, coupled to information on the knowledge, environmental perception and level of the advisors participation. Data were also taken on the advisors profile and on their decisions recorded in minutes of meetings. Results show limited knowledge of environmental legislation and a general perception that deficient inspections undertaken by public agencies are responsible for environmental degradation. No possibility of a joint action between government and society has been taken into consideration for the establishment of a new efficient and efficacious participation process. Although deficiencies existed, environmental gains were detected in the Council’s decisions.

System of Multiple Sex Chromosomes in Eigenmannia trilineata Lopez & Castello, 1966 (Sternopygidae, Gymnotiformes) from Iguatemi River Basin, MS, Brazil

The genus Eigenmannia belongs to the family Sternopygidae, a monophyletic group of Neotropical electrogenic fish. Eigenmannia trilineata from Iguatemi River basin were analyzed using classical cytogenetic techniques. Chromosomes of this species of Eigenmannia presented a X1X1X2X2 : X1X2Y sex chromosome system, with 2n=31chromosomes for the males and 2n=32 for the females, where the Y is metacentric chromosome originated from Robertsonian translocation. The NORs are located interstitially on the long arm of chromosome pair 10. Constitutive heterochromatin is distributed in very conspicuous blocks at the juxtacentromeric regions acrocentrics chromosomes in the males and females, including the unique large metacentric neo-Y in the males also presented a juxtacentromeric block. The chromosomal data obtained may be useful for the taxonomy and phylogenetic studies in this fish group.

Cytogenetic Studies Comparing Three Characidae Fish Species from the Iguatemi River Basin, Brazil

Characidae is one of the predominant fish groups in the Neotropical region with approximately 30 highly diversified subfamilies, probably not representing a monophyletic group. Three Characidae species from the Iguatemi River Basin (Mundo Novo, MS, Brazil) were analyzed: Astyanax bockmanni with 2n=50 chromosomes (6m+20sm+8st+16a), Bryconamericus stramineus with 2n=52 chromosomes (6m+10sm+16st+20a) and Piabina argentea with 2n=52 chromosomes (6m+24sm+12st+10a), all the species showing no differences between male and female karyotypes. The Ag-NORs were located in only a single chromosome pair in the three species. The chromosomal data obtained may be useful for the taxonomy and phylogenetic studies in these fish groups.

Ecology of Phallotorynus pankalos (Cyprinodontiformes: Poeciliidae) in a first-order stream of the upper Paraná Basin

Some aspects of the population ecology of Phallotorynus pankalos in a first-order stream of the Iguatemi River Basin are described based on samples taken from March/2007 to February/2008. A total of 2680 individuals, including 948 males and 1732 females was collected. Adult females are larger than males; theirs mean fecundity was estimated as 6.5 embryos/female. There was a strong correlation between standard length and ovary weight, relative ovary weight, and number of embryos. The size of the first maturation of 50% of female population was estimated as 18.24 mm of standard lenght. High female mortality was observed after the first reproduction and sex ratio presents seasonal variation with higher female proportion in the winter.

Gradientes de diversidade nas comunidades de peixes da bacia do rio Iguatemi, Mato Grosso do Sul, Brasil

Com o objetivo de verificar a importância da variação longitudinal, sazonal e a influência das características físicas e químicas da água sobre a diversidade de espécies de peixes realizamos amostragens trimestrais, entre Novembro/1999 e Agosto/2000, em três pontos amostrais no rio Jogui e oito pontos amostrais no rio Iguatemi-MS. A variação longitudinal foi mais importante que a variação sazonal na determinação da riqueza e número de indivíduos no rio Jogui, no entanto, a equitabilidade não apresentou diferença significativa sazonal ou longitudinal. No rio Jogui 78,3% da variação na riqueza de espécies, 81,6% no número de indivíduos e 41,1% na equitabilidade foram explicadas pelas características físicas e químicas da água. No rio Iguatemi nós não detectamos diferenças estatisticamente significativas longitudinais ou sazonais nos descritores analisados das comunidades nem influência significativa dos fatores ambientais.

Organização das assembléias de peixes em riachos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul

Aiming to describe the patterns of the fish assemblages organization in streams of the Iguatemi River basin we sampled streams with seine nets and sieves from November/1999 to August/2000. We collected 567 individuals distributed in 24 species. We detected statistically significant influence of the streams characteristics upon species diversity. The species composition was hardly explained by the physical and chemical characteristics of the streams. Then we detected significant influence of the fish ecomorphology in the species occurrence (Mantel r = -0,34; P = 0,04), but not in the distribution of its abundance (Mantel r = -0,21; P = 0,07). We verified through the species co-occurrence index (C-score) that its composition in the studied streams is stochastic

Associações de espécies de peixes em ambientes lóticos da bacia do rio Iguatemi, Estado do Mato Grosso do Sul

The aim of this paper is to describe the patterns of associations between fish species and their distribution in lotic habitats at basin level. Samples were accomplished in 27 localities of Iguatemi river basin, distributed in four environments (Iguatemi river, Jogui river, Puita river and streams). The presence/absence data of those species which occurred in 2 or more sites were submitted at multivariate methods with the aim to describe the major species associations. The species distribution was considered determinative in these communities (C-score = 17,33; P = 0,000), with significant difference among the studied environments (ANOSIM r = 0,082; P = 0,012), with verified difference between Iguatemi river and streams (P = 0,001) and also streams and Jogui river (P = 0,014). We verified a strong segregation among species from headstreams and more discharge river stretches or even larger streams

Colonização ictiofaunística do Reservatório de Itaipu e áreas adjacentes

Samples were taken from November 1983 to October 1989 in sites along the main body of the Itaipu reservoir and its area of influence to evaluate the impacts of this reservoir on ichthyofauna and to provide information about the colonization process in the dammed area. The ichthyofaunistic similarity between the sites was analysed during the studied period. Spatial and temporal variations of the ichthyofaunistic diversity were also done, using Shannon-Winer Index of Diversity, eveness and species richness, comparing the results with those obtained before the damming. After Itaipu Reservoir formation, it was observed significative alteration in specific abundance and ichthyofauna structure of the Parana River, with an increase in species number in ali tributaries of the reservoir, and a high replacement in species. Diversity and species richness were higher in the dammed stretch of the Parana river and in its tributaries of the left side after the Itaipu reservoir formation. Among the sampled sites, the highest values of the diversity index were registered in Parana River upstream and downstream the reservoir, Iguatemi river and Arroio Guacu. Based on information of similarity in species composition and abundance in the sampled area, five site groups could be identified.