Rosilene Luciana Delariva

Food-resource partitioning among fish species from a first-order stream in northwestern Paraná, Brazil

This study addressed the feeding ecology of fish fauna from a first-order stream located in a rural area. The purposes were to evaluate the influence of interspecific, seasonal and spatial factors on the diet, examine the dietary overlap, and determine the predominant food sources. Sampling was conducted in December 2007, September 2008, and March 2009, in three 50-m stretches of Itiz stream (upstream, intermediate, and downstream), through electrofishing. A total of 1,102 stomach contents were analyzed from 14 species, by the volumetric method. In general, allochthonous resources were predominant in the diets. Astyanax aff. fasciatus, Astyanax aff. paranae, Astyanax bockmanni, and Bryconamericus aff. iheringi consumed a higher proportion of plant remains, and Bryconamericus stramineus consumed predominantly Hymenoptera. The diets of Cetopsorhamdia iheringi, Characidium aff. zebra, Imparfinis schubarti, and Trichomycterus sp. consisted of aquatic insects, especially immature forms of Trichoptera, Ephemeroptera, Plecoptera, and Diptera. Hypostomus ancistroides, Hisonotus sp., Poecilia reticulata, and Rineloricaria aff. pentamaculata exploited mainly detritus, while Rhamdia quelen used a variety of items, predominantly terrestrial insects. Detrended Correspondence Analysis (DCA) showed a clear distinction among the species, with different morphology and feeding tactics. The Multi-Response Permutation Procedure (MRPP) supported this differentiation, and also indicated significant spatial and temporal variations in the dietary composition; the Indicator Value Method (IndVal) indicated the main items that contributed to these differences. The diet overlap among species was low (< 0.4) to around 78% of pairs, and the mean value did not vary significantly among the sites or between hydrological periods within each site. According to the null model of Pianka’s index, the values for dietary overlap were significantly higher than expected at random, showing evidence of resource sharing. This was related to the availability of allochthonous resources, highlighting the importance of riparian vegetation as a source of these resources for maintaining the fish fauna of the stream.

Fish larvae assemblages in two floodplain lakes with different degrees of connection to the Paraná River, Brazil

The objective of this study was to assess the abundance, attributes of assemblages, and spatial and temporal distributions offish larvae and their relationships with some abiotic variables in two floodplain lakes with different degrees of connection tothe Parana River in Ilha Grande National Park, PR, Brazil. Four sampling sites were chosen, two in each floodplain lake. Nightsamples were taken with plankton nets during three spawning seasons (monthly, from October to March) from 2001 to 2005.The highest diversity and abundance were recorded at Saraiva Lake, with 25 taxa being identified. In Xambre Lake, onlysedentary species were captured, and the most abundant species were

Spatial and temporal distribution patterns of ichthyoplankton in a region affected by water regulation by dams

The aim of this work was to study the occurrence of ichthyoplankton in a region affected by water regulation by dams. The study area was located in the region of Ilha Grande National Park, upper Parana River floodplain. Specifically, we examined the temporal and spatial distribution of Ichthyoplankton, identified spawning areas and established the relationships between the abundances of fish eggs and larvae and some limnological and hydrological variables. Samples were taken monthly between October and March from 2001 to 2005 at 24 sampling sites. For analytical purposes, the sampling sites were grouped into upper, middle and lower areas. The upper area of the National Park had the highest egg density and should be considered the primary spawning area. The middle area should be considered a drift area, and the lower area likely functions as a growth and feeding habitat. Statistical analyses showed that the spawning was influenced by water temperature, pH, fluviometric level and rainfall, and that larval density was influenced by pH, conductivity, dissolved oxygen and rainfall. The results also revealed that the tributaries apparently are used as migratory routes by fish, and and this shows the need to protect these sites.

Diet and trophic structure of the fish fauna in a subtropical ecosystem: impoundment effects

Neste estudo foram avaliadas a dieta e a estrutura trofica da ictiofauna em escala temporal e espacial, sob efeito do represamento do rio Iguacu, na regiao de Salto Caxias, Parana, Brasil. Para tanto, foram realizadas amostragens nas fases pre (marco/97 a fevereiro/98) e pos represamento (marco/99 a fevereiro/00) em quatro pontos de coleta. Os conteudos estomacais foram avaliados pelo metodo volumetrico. As especies foram organizadas em 10 guildas troficas: algivora, carcinofaga, detritivora, herbivora, insetivora aquatica, insetivora terrestre, invertivora, omnivora, piscivora e planctivora, sendo a primeira e a ultima representadas apenas apos o represamento. Os padroes de similaridade e alteracoes na dieta foram sintetizados atraves da ordenacao multidimensional nao parametrica (nMDS) e estatisticamente testados pela analise de variância permutacional (PERMANOVA). Foram constatadas alteracoes na dieta da maioria das especies, com excecao das piscivoras e detritivoras. Essas alteracoes foram relacionadas ao fator temporal (fases do represamento), configuradas como reducao no consumo de organismos bentonicos e alimentos aloctones, os quais foram geralmente substituidos por recursos provenientes do proprio ambiente (algas, microcrustaceos e peixes), simplificando o espectro alimentar. Diferentes recursos alimentares indicadores (IndVal) corroboram essas alteracoes na composicao alimentar das especies antes e apos o represamento. As proporcoes na abundância (numero e biomassa) das guildas troficas avaliadas com base na captura por unidade de esforco (CPUE) e testadas pela ANOSIM foram significativamente diferentes antes e apos o represamento. As guildas herbivora e piscivora foram as que mais contribuiram (SIMPER) para essas diferencas, especialmente o elevado incremento em biomassa da guilda piscivora apos o represamento. As variacoes na abundância das guildas troficas foram mais relacionadas as alteracoes no habito alimentar da fauna de peixes, do que propriamente aos incrementos em numero e em biomassa das especies que anteriormente compunham tais guildas.

Benthic macroinvertebrate community structure in a stream of the north-west region of Paraná State, Brazil

This study aimed to survey the benthic macroinvertebrate fauna of a first order stream located in an agricultural area, and to assess the environmental factors involved in the spatial distribution of this community. Invertebrates were gathered in November 2007 at three sampling sites distributed along the Itiz Stream, located in Marialva municipality, Parana State. At each site, we measured the physical and chemical variables of the water, and then took four samples, using Surber sampler. In order to evaluate the differences in density, richness, diversity and evenness, we employed an ANOVA and a DCA to summarize biotic data. The invertebrates were categorized into functional groups and the BMWP score was applied to calculate the biological integrity of the environment. The faunal composition was represented by 103 taxa distributed across five phyla, of which the highest occurrence was of arthropods, especially insects. Higher density values were observed for Chironomidae, Ephemeroptera, Coleoptera and Trichoptera. The richness, diversity and density, as well as the density of gathering-collectors, were higher in the intermediate course of the stream. The distribution pattern of the taxa was mainly influenced by lentic or lotic characteristics of the sampled sites and microhabitats, as evidenced by the DCA. The BMWP indices indicated that the three sampling sites presented scores of excellent and good water quality. In the Itiz Stream, the presence of preserved marginal vegetation and the distance from urban centers that generate pollution, combined with peculiarities of each sampling site, influenced the structure of the benthic community.

Fishes in first order stream in Ivaí River drainage basin, upper Paraná River Basin, Paraná state, Brazil

Itiz Stream is a first order tributary of the Ivai River basin, located in a rural area of Marialva municipality, Parana state. Fish were sampled in October, November and December 2007, September 2008 and March 2009, using electrofishing and a sieve technique in three stretches along the stream. We collected 20 species belonging to 13 genera, seven families and three orders. Only Po ecilia reticulata was considered non-native species and five are probably undescribed.

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.

Use of food resources by small fish species in Neotropical rivers: responses to spatial and temporal variations

Spatial and temporal variations in food supply play a crucial role in the determination of the patterns of food use by fish species. This study evaluated spatial and temporal variations in food utilization by small fish species of the Verde River, Upper Parana River Basin, state of Mato Grosso do Sul, Brazil. Samplings were conducted in the rainy and dry periods, from November 2010 to August 2012, using trawls, cast nets and gillnets, in nine sampling sites grouped into three biotopes: upstream and downstream of the Branca Waterfall, and tributary. The stomach contents of 3,263 individuals of 12 small species were examined according to the volumetric method. Altogether, 31 food items were identified. Overall seed consumption was greater in the rainy period, and the consumption of terrestrial plants was greater in the dry period. Hymenoptera was an important item in the diet, but the proportions in the consumption of this item was different between biotopes and periods. The consumption of Coleoptera and Isoptera was expressive only downstream of the Branca Waterfall in the rainy period, and aquatic plant was mostly consumed in the tributary in the dry period. Significant differences were detected in the diet composition between biotopes, hydrological periods and also the interaction between these two factors. Allochthonous resources were clearly the most consumed by the species in all biotopes, especially during the rainy period. The dietary overlap between species, although showing significant spatial and temporal differences, was low (0.4) for about 60% of species pairs. Thus, it is concluded that spatial and temporal changes in the utilization of food resources by small fish were related to physiographic differences of the channel and the surroundings, which contributed to the significance of seasonal changes in the diet, also reflecting the low dietary overlap between species.

Fish fauna of headwater streams of Perobas Biological Reserve, a conservation unit in the Atlantic Forest of the Northwestern Paraná state, Brazil

The Perobas Biological Reserve is a Conservation Unit characterized by two physiognomies of the Atlantic Forest: Semideciduous Seasonal Forest and Mixed Ombrophilous Forest. The reserve is situated on a ridge watershed between the basins of the Piquiri and Ivai rivers, Upper Parana River and had its fish fauna surveyed for the first time. Fishes were collected quarterly from December 2010 to March 2012, using electrofishing in five stretches of 50 m along the four streams, and gillnets only at one site in December, 2010. A total of 2628 individual were collected, belonging to 34 species in 25 genera, 13 families and six orders. Ten taxa may be new species or part of a complex of species within each genus, and requiring more detailed taxonomic revisions. Nine species are the first records for the Piquiri river basin.

Use of Muscular Cholinesterase of Astyanax bifasciatus (Teleostei, Characidae) as a Biomarker in Biomonitoring of Rural Streams

Cholinesterase (ChE) activity was measured in Astyanax bifasciatus maintained in controlled conditions. Muscle ChE activity of individuals collected in field conditions in two seasons was compared among specimens collected in seven streams (forest and rural) of the lower Iguaçu river basin in association with physical, chemical, pesticides and biological factors. Significant differences in muscle ChE activity between control fish and fish collected in streams in both seasons were found, with higher activity in natural conditions. This the first time that differences in muscle ChE activity have been found among fish collected from different streams, suggesting synergism among multiple factors (e.g. temperature, pH, animal weight) and ecological attributes (richness and abundance) as influencing the variation in biomarkers. It is necessary to evaluate the quality of aquatic environments for a more accurate biomonitoring approach.