Benthic macroinvertebrates in the Paranapanema reservoir cascade (southeast Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproductive biology of Palaemon pandaliformis (Stimpson, 1871) (Crustacea, Decapoda, Caridea) from two estuaries in southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Occurrence of Pseudosida ramosa Daday, 1904 (Crustacea: Cladocera: Ctenopoda) in marginal lakes of the Paranapanema River, with comments on its distribution.

Aim: Contribute to the understanding of the distribution of a littoral cladoceran, Pseudosida ramosa Daday, 1904, in Brazil, with special reference for the Paranapanema River basin (Southeast Brazil); Methods: The specimens were sampled in two floodplain lakes located in the middle Paranapanema River basin, in the boundary of São Paulo and Parana States, using a standard plankton net (50 [mu]m mesh size). Trinocular microscopic with camera lucida and milimetric scale was used for the observation and measurements of the specimens; Results: Only three individuals were found (in winter and summer), despite of an extensive sampling program during 17 consecutive months of observations in both lakes. The largest body length was 1,146 [mu]m. The taxonomical identification followed Korovchinsky (1992); Conclusions: This species have a wide geographical distribution in Brazil, but it is restricted to zones colonized by aquatic macrophytes and seems to occur in low population abundance. The scarcity of registers of P. ramosa demonstrates the necessity of deeper investigations of littoral habits as well as the important role of this kind of environment for the conservation of the rivers/reservoirs biota, including some possible rare species.

The invasion of five alien species in the Delta do Parnaiba Environmental Protection Area, Northeastern Brazil

Marine biological invasions have been regarded as one of the major causes of native biodiversity loss, with shipping and aquaculture being the leading contributors for the introductions of alien species in aquatic ecosystems. In the present study, five aquatic alien species (one mollusk, three crustaceans and one fish species) were detected during dives, shore searches and from the fisheries on the coast of the Delta do Parnaiba Environmental Protection Area, in the States of Piaui and Maranhao, Northeastern Brazil. The species were the bicolor purse-oyster Isognomon bicolor, the whiteleg shrimp Litopenaeus vannamei, the giant river prawn Macrobrachium rosenbergii, the Indo-Pacific swimming crab Charybdis hellerii and, the muzzled blenny Omobranchus punctatus. Ballast water (I. bicolor, C. hellerii, and O. punctatus) and aquaculture activities (L. vannamei and M. rosenbergii) in adjacent areas are the most likely vectors of introduction. All exotic species found have potential impact risks to the environment because they are able to compete against native species for resources (food and habitat). Isognomon bicolor share the same habitat and food items with the native bivalve species of mussels and barnacles. Litopenaeus vannamei share the same habitat and food items with the native penaeids such as the pinkspot shrimp Farfantepenaeus brasiliensis, the Southern brown shrimp Farfantepenaeus subtilis, and the Southern white shrimp Litopenaeus schmitti, and in the past few years L. vannamei was responsible for a viral epidemics in the cultivation tanks that could be transmitted to native penaeid shrimps. Charybdis hellerii is also able to cause impacts on the local fisheries as the species can decrease the populations of native portunid crabs which are commercialized in the studied region. Macrobrachium rosenbergii may be sharing natural resources with the Amazon River prawn Macrobrachium amazonicum. Omobranchus punctatus shares habit with the native redlip blenny Ophioblennius atlanticus and other fishes, such as the frillfin goby Bathigobius soporator. Some immediate remedial measures to prevent further introductions from ballast water and shrimp farm ponds should be: (i) to prevent the release of ballast water by ship/vessels in the region; (ii) to reroute all effluent waters from shrimp rearing facilities through an underground or above-ground dry well; (iii) to install adequate sand and gravel filter which will allow passage of water but not livestock; (iv) outdoor shrimp pounds located on floodable land should be diked, and; (v) to promote environmental awareness of those directly involved with ballast water (crews of ship/vessels) and shrimp farms in the region. Rev. Biol. Trop. 58 (3): 909-923. Epub 2010 September 01.

Effects of flooding regime and woody bamboos on tree community dynamics in a section of tropical semideciduous forest in South-Eastern Brazil

The influence of a population of the understorey woody bamboo Merostachys riedeliana and different flooding regimes on tree community dynamics in a section of tropical semideciduous forest in South-Eastern Brazil was examined. A forest section with an area of 1.6 ha composed of 71 adjacent plots was located on a slope ending at the river margin. The section was divided into five topographical sectors according to the mean duration of river floods. In 1991 and 1998 all trees with a diameter at the base of the trunk greater than or equal to 5 cm were measured, identified and tagged, and all live bamboo culms were counted. Annualised estimates of the rates of tree mortality and recruitment, gain and loss of tree basal area, and change in bamboo density were calculated for each of the 71 plots and five topographical sectors as well as for diameter classes and tree species. To segregate patterns arising from spatially autocorrelated events, geostatistical analyses were used prior to statistical comparisons and correlations. In general, mortality rates were not compensated by recruitment rates but there was a net increase in basal area in all sectors, suggesting that the tree community as a whole was in a building phase. Tree community dynamics of the point bar forest (Depression and Levee sectors) differed from that of the upland forest (Ridgetop, Middle Slope and Lower Slope sectors) in the extremely high rates of gain in basal area. The predominant and specialised species, Inga vera and Salix humboldtiana, are probably favoured by relaxed competition in an environment stressed by long-lasting floods. In the upland forest, mortality rates were highest at the Middle Slope, particularly for smaller trees, while recruitment rates were lowest. As bamboo clumps were concentrated in this sector, the locally higher instability in the tree community probably resulted from the direct interference of bamboos. The density of bamboo culms in the upland forest was negatively correlated with the rates of tree recruitment and gain in basal area, and positively correlated with tree mortality rates. Bamboos therefore seemed to restrict the recruitment, growth and survival of trees.

Aquatic macrophyte distribution in relation to water and sediment conditions in the Itaipu Reservoir, Brazil

Aquatic macrophyte community distribution along the eastern shoreline of the Itaipu Reservoir (one of the South America's largest impoundments) is described in relation to limnological and sedimentological factors. The central body of the reservoir is mesotrophic, while the arms (flooded influent river valleys) along the eastern shore may be oligo-mesotrophic to eutrophic, depending on time of year and sub-catchment characteristics. Macrophyte community composition and species cover were surveyed at 30 sites in four arms, in relation to sediment total P and organic matter; underwater light regime; and water total P and Kjeldahl N concentration, alkalinity, conductivity, depth and pH. Seventeen euhydrophyte and six emergent macrophyte species were recorded. Large stands of Egeria najas dominated the euhydrophyte vegetation, together with free-floating weed species (Pistia stratiotes Linn., Salvinia auriculata Aublet and Eichhornia crassipes (Mart.) Solms.). Canonical Correspondence Analysis of the data showed that two sets of variables were important predictors of aquatic macrophyte community structure. Floating macrophyte assemblage was closely related to concentration of nutrients in both water and sediment, while light penetration was the strongest predictor of submerged species occurrence. Although a large number of potential nuisance species were present, dense growths were restricted to shallower areas of the Itaipu Reservoir, causing localised problems. The possibility of increasing interference by these plants with fisheries, recreational use, transport and hydroelectricity generation suggests a need for continued monitoring of weed distribution and abundance, and investigation of appropriate management measures.

Adaptation of the reservoir fish assemblage index (RFAI) for assessing the Barra Bonita Reservoir (São Paulo, Brazil)

In order to evaluate the environmental condition of the Barra Bonita Reservoir, we adapted the Index of Biotic Integrity (IBI). We chose 24 sampling sites in which three types of habitats were sampled: the mouths of tributaries, the central reservoir and the lateral reservoir. Fish were caught in two seasons (dry and rainy) using 10 gillnet gangs, with meshes ranging from 3 to 12 cm between opposite knots, and funnel traps. Abiotic and biotic variables were measured. Due to the artificial nature of the reservoir, the term biotic integrity was considered inappropriate and the term RFAI (Reservoir Fish Assemblage Index) was adopted. Twelve metrics from sixteen possibles were selected using the Pearson correlation coefficient. The reference conditions were set up based on the criteria of the best condition observed. For each metric, a score of 1, 3 or 5 was assigned as it strongly departs (1), slightly departs (3) or approaches (5) the reference condition. The index value is the sum of the metrics partial scores and ranges from 12 to 60. To evaluate the importance of the unit of measurement of the metric, the index was calculated in fish number (RFAI(N)) and in weight (RFAI(w)). The correlation between RFAIN and RFAIw was very high (r = 0.90, n = 46) indicating that the unit of measurement does not influence the final result of the index. Most of the sampling sites were classified in the 'reasonable' RFAI category. Only the central sites were classified as 'poor'. To validate the RFAI, another index, the Habitat Quality Index (HQI), was built starting from the physiochemical and habitat variables collected. The correlation of the RFAI with the HQI was highly significant (RFAIN, r = 0.37; RFAI(w), r = 0.47; n = 46), indicating that they respond in the same way to environmental degradation. The HQI metrics which most affect RFAI were depth, surrounding landscape and macrophyte presence/absence. Copyright C) 2007 John Wiley & Sons, Ltd.

Factors regulating diversity and abundance of fish communities in Pantanal lagoons, Brazil

The factors effecting fish species richness, evenness and relative abundance in 19 floodplain lagoons in the Pantanal (Brazil) were examined. Richness and evenness were strongly correlated with the lagoon's: (i) isolation time from the main river; (ii) depth; and (iii) distance from the main river. Abundance of the five dominant fish species was correlated mainly with: (a) macrophyte cover; (b) the distance from the main river; and (c) piscivore abundance. These results suggest that the species select lagoons to avoid or minimize their confinement in inappropriate floodplain habitats. A combination of strategies, together with variations in the lagoon's connection period, determines the diversity and abundance of the fish species in the Nhecolandia Pantanal.

Factors determining the structure of fish communities in Pantanal lagoons (MS, Brazil)

The fish communities of lagoons in the Nhecolandia Pantanal were studied to determine the factors which are responsible for the composition and abundance of species. Fishes were collected in 19 lagoons during August 1997, after their isolation from the River Negro, using beach seines (15 x 1.5 m; 2 mm mesh). A total of 51 species were collected. In the lagoons, or in parts with dense macrophytes, a screened box trap was used. Fishing was also accomplished with hooks of several sizes. Species richness was estimated by the jack-knife procedure, after adjustment to the log-normal distribution and with von Bertalanffy's equation (asymptotic). The most important factors in the community organization were macrophyte cover, piscivore abundance and depth of the lagoons. The role of these habitats in the Pantanal ecosystem was discussed.

Fish community alterations due to pollution and damming in Tiete and Paranapanema rivers (Brazil)

The Tiete River crosses the metropolitan region of São Paulo (Brazil) and receives a large amount of pollution, in contrast to Paranapanema River which runs in a less populated area. In the inferior portions of the basins of these rivers, a series of reservoirs has been built for hydroelectric energy generation which improve the water quality due to the decantation of suspended soils and aeration in the water spills.Twenty-nine sampling sites were established along the two rivers and in each sampling site, two groups of eight gillnets were used with standardized sizes in two seasons: winter (dry season: June-September 1994) and summer (rainy season: December-March 1995). The fishes were measured and weighed.Twenty-five parameters related. to the water were recorded. PCA and cluster analysis helped to identify two groups of sampling sites. The first one corresponds to the rainy season samples, while the second corresponds to the dry season samples, so evidencing strong seasonal environmental variation. However, the dry season group is still divided into polluted and non-polluted sites, showing that during drought there are larger effects of pollutant concentration due to the decreased flow.A total of 415 kg of fish were caught, corresponding to 8324 individuals belonging to 64 different species, in 22 families and four orders of Teleostei. The largest catches occurred in the middle Tiete River. The catches in the reservoirs of the Tiete River, during the rainy season are superior to those of the dry season. on the other hand, sampling sites located in running water presented an inverse pattern with the largest catches in the dry-season. In river Paranapanema, catches are lower than in the Tiete River, except in Rosana Reservoir during the rainy season. Fish diversity was shown to be a good-indicator of environmental stress. In Tiete River an expressive fall in species richness was detected in the polluted stretches, with dominance of one or two species. In the intermediary stretches, the presence of rapids increases the amount of dissolved oxygen, allowing the development of the most abundant and diverse fish community of the river. Fish communities in the reservoirs of the inferior stretch of Tiete River are more diverse. on the other hand, the damming of the superior reaches of Paranapanema River provoked a decrease in diversity. 0 the whole, types of local fish communities detected, showing different compositions and specific abundances, revealed different ecological situations. A discriminant analysis revealed that the parameters of the water influencing the fish community were: dissolved oxygen, conductivity, nitrogen (nitrate, ammoniacal and albuminoid), phosphate, alkalinity, hardness and iron. Copyright (C) 2003 John Wiley Sons, Ltd.

Health variables and gill morphology in the tropical fish Astyanax fasciatus from a sewage-contaminated river

The relative condition factor (Kn), gonadosomatic index (GSI), selected hematological variables and gill morphology of the fish Astyanax fasciatus were analyzed in two sites (site I was unpolluted and site 2 was polluted with untreated domestic sewage) of a tropical river (Camanducaia river, São Paulo State, Brazil). The relationship between the body mass (M-B) and the standard length (L-S) of A. fasciatus from both sites was M-B = 0.00799 L-S(3.51843). Tyhe Kn values from both the males and females were significantly higher in site 2. The mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were higher in females from site 2. Gill tissue anomalies and gill parasites were rare in fish from both sites; however, the number of chloride cells was significantly higher in fish from site 1. A. fasciatus presents high capacity to live in ion-poor and soft water and is able to compensate for environmental changes caused by untreated domestic sewage discharges. (c) 2004 Elsevier B.V. All rights reserved.

Spatial and temporal patterns and their influence on fish community at Itupararanga Reservoir, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Reproduction of a fish assemblage in the state of São Paulo, southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Feeding of Oligosarcus hepsetus (Cuvier, 1829) (Characiformes) in the Serra do Mar State Park - Santa Virgínia Unit, São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ichthyofauna diversity in a protected area in the state of São Paulo, southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)