Biological Invasions in Neotropical Regions: Continental Ichthyofauna and Risk Assessment Protocols

The objectives of this study were to compare four risk assessment protocols for non-native species in neotropical regions and to assess the potential application of these tools for the management of invasive species and conservation of the ichthyofauna in Brazil. The protocols Fish Invasiveness Screening Kit (FISK), Aquatic Species Invasiveness Screening Kit (AS-ISK), European Non-Native Species in Aquaculture Risk Assessment Scheme (ENSARS) and Fish Invasiveness Screening Test (FIST) were applied for the species Oreochromis niloticus, Coptodon rendalli, Poecilia reticulata and Apteronotus aff. albifrons, whose sources of introduction are aquaculture and fishkeeping. The species were classified as low, medium or high risk of invasion. The scores of the species O. niloticus, C. rendalli and P. reticulata classified them as high risk of invasion in all protocols, whereas A. aff. albifrons had medium risk in the protocols FISK and AS-ISK and low risk in the FIST. Although the results were similar for species whose impacts are widely described, less studied species may have their classification compromised by the lack of evidences in the literature. Despite the difficulties for practical application, the use of these tools may be encouraged, considering the potential threats of other invasive species emerging in Brazil. The comparison between the methods showed that the use of AS-ISK, combined with ENSARS in cases of introductions by aquaculture, provides important answers about ecological impacts on natural environments and about the stages of the aquaculture production chain that should be better inspected.

Diagnostic value of electrocardiograms to identify pericardial effusion in acute malaria: a cross-sectional study

Background

Patients with acute malaria are at risk of pericarditis and may benefit from timely identification of pericardial effusion. However, diagnostic imaging tools, such as echocardiography, are not always available in malaria endemic regions.

Purpose

The aim of this study is to examine the diagnostic yield of pathology in electrocardiograms (ECG) to identify pericardial effusion in acute malaria.

Methods

We enrolled adult acute malaria patients in community healthcare clinics in a remote area in South America. All patients underwent ECG, echocardiography, and peripheral blood smears. We excluded patients on anti-malarial medication, suspected concomitant infection and pregnant women. All ECGs were examined for the following criteria: (i) PR-depression >0.5mm and/or ST-elevation 0.5–1mm (I, II, aVL, aVF, V2–6) (ii) PR-elevation >0.5mm (only aVR), (iii) ST/T-ratio >0.25 (only V6), (v) low voltage, defined as QRS amplitude <5 mm in limb leads or <10 mm in precordial leads, and (vi) Spodick's sign (all leads). A criterion was positive when present in ≥2 leads. Information on shortness of breath and/or chest pain was also collected. Pericardial effusion was diagnosed by echocardiography and had to be ≥0.5cm in width.

Results

We included 99 non-severe malaria patients (age 40±15 years, 55% men, median parasite density 1517/mm3, [interquartile range 528 to 6,585/mm3]) who suffered from Plasmodium vivax (n=75), falciparum (n=22 falciparum) and mixed vivax/falciparum (n=2). The ECGs showed a mean frequency of 78±16bpm, PR-interval 147±20ms, QRS 88±11ms and QT-interval 376±34ms. A total of 11 patients displayed pericardial effusion (mean width 0.9±0.3cm, n=7 vivax, n=2 falciparum, n=2 mixed). Patients with effusion were older (mean age 39 vs 53 years, P=0.003), but displayed no difference in sex, parasite density or parasite species compared to patients without pericardial effusion (P>0.05). Distribution of ECG findings and symptoms are displayed in figure 1A. PR-depression had a sensitivity and specificity for diagnosing pericardial effusion of 73% and 90%, respectively. The sensitivity and specificity for other ECG findings and clinical symptoms are displayed in Figure 1B.

Conclusion

ECG findings may aid in identifying pericardial effusion in acute malaria, specifically PR depression which had a diagnostic yield of 73% sensitivity and 90% specificity. Based on this, ECG in acute malaria may improve treatment and risk stratification when echocardiography is not an option.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Novo Nordisk Foundation, Independent Research Fund Denmark ECG findings in malaria patients

Do river basins influence the composition of functional traits of fish assemblages in Neotropical reservoirs?

In aquatic environments, dams are considered one of the main threats to fish species, acting as an environmental filter for certain functional traits. Although there is some predictability in the composition of the functional traits in reservoirs, it is hypothesized that the environmental filters imposed by evolutionary processes, linked to the characteristics of the basins, are determinant for the functional composition of the traits in reservoirs. For this we performed a PCoA using the functional traits composition matrix of the reservoirs. We used PERMANOVA to test the difference in functional composition between basins. We performed the same process for the species composition matrix to compare the patterns. In this study, there were taxonomic and functional differences among reservoirs inserted in different basins. It was observed that the basin is a determining factor for the functional structure of fish assemblage in reservoirs. When compared, functional and taxonomic structures follow the same pattern, although functionally the reservoir tends to be more similar. These results reinforce the idea that reservoirs act as filters for functional traits (e.g., related with reproduction, feeding and habitat use), although there is a great influence of evolutionary processes related to the basin's characteristics and origin of the ichthyofaunistic province.

Effects of reservoir cascades on diversity, distribution, and abundance of fish assemblages in three Neotropical basins

River systems are characterized by the existence of longitudinal processes structuring fish assemblages. However, the construction of dams, many of them built in cascades, are disrupting these processes worldwide. Here, we analyzed the fish assemblages across reservoir cascades in three Brazilian river basins (Iguaçu, Paranapanema, and São Francisco) to identify whether there is a spatial convergent pattern and to infer the mechanisms structuring metacommunities in these Neotropical rivers. Linear models were used to assess the effect of reservoir cascades, and the associated morphological, spatial and environmental variables, on the species richness and diversity along them. We analyzed if reservoir cascades produce similar species distribution patterns using the elements of metacommunity structure framework and beta diversity and its components. Finally, super-organizing maps were used to find common trends in species abundances and the environmental, morphological, and spatial variables along cascades. The negative relationship between species richness and diversity and the position in the cascade indicated diversity declines along cascades. However, the resulting metacommunities varied in each river basin. They conformed a quasi-Gleasonian structure, a Clementsian structure, and a nested structure with stochastic species loss in the Iguaçu, Paranapanema, and São Francisco River basins, respectively. Generally, total beta-diversity (βsor) and species turnover (βsim) between pairs of reservoirs increased along reservoir cascades, especially at the downstream end, whereas nestedness (βsne) depicted distinct trends in each river basin. By contrast, there were general decreases in species abundances along cascades, especially downstream the fourth reservoir, with very few species benefiting from such situation. In general, species present in the downstream reservoirs were subsets of the species present in the upstream reservoirs (particularly in the São Francisco River Basin), while some had singular responses to the environmental gradient and appeared or disappeared at random. Although the cascade has an effect on fish assemblages, reservoir characteristics and operation also influence them. Our study highlights the impact of such structures and shows general patterns of fish assemblages that should help to mitigate the resulting ecological impacts and assist the process of infrastructure planning.

Adjustments in population and reproductive dynamics of native and non-native congeneric species during 26 years after invasion

ABSTRACT We aimed to improve the understanding of the establishment of Serrasalmus marginatus (non-native), which was followed by a decrease in the abundance of Serrasalmus maculatus (native) in the upper Paraná River floodplain. We estimated age, mortality rate, length and age at first maturity and variations in gonad development in three time-periods along a 26-year truncated time scale for both species. Population and reproduction parameters of both species showed substantial fluctuations among periods. Most age classes were sampled in all time-periods, but with considerable difference in abundance, with predominance of older individuals in the second time-period and younger individuals in the third time-period for both species. The mortality rates decreased for both species in the second time-period, but increased for the native in the third time-period. Length and age at first maturity decreased in the second time-period for both species, increasing the number of mature individuals on their populations. In the third time-period, the number of immature individuals increased for both species. We suggest that species experienced stressful conditions during cooccurrence and this have resulted in physiological responses in both species, reflecting in population and reproductive adjustments that may have relaxed competitive interactions between them, optimizing survival, reproductive effort and coexistence.

Fish die-off in river and reservoir: A review on anoxia and gas supersaturation

Abstract Albeit massive fish mortality has an extraordinary visual impact and is certainly a fatality, we still have rudimentary understanding on how addressing this problem in the Neotropical region. The processes that lead to fish die-off events are complex and sometimes ephemeral, which can lead to incorrect diagnosis. In this review, we discuss these events in Neotropical freshwaters, both in areas impacted by dams and natural environment, with a focus on deaths mediated by the lack of oxygen (anoxia) or the excess of dissolved gases (gas supersaturation). We examine the available knowledge about the related mechanisms, lethal thresholds for dissolved oxygen (DO) and total dissolved gases (TDG) for fish, and the sequelae of gas bubble disease (GBD). An assessment of the main mortality events in Brazil in the last 10 years is also presented, as well as the best practices for monitoring, prevention, and mitigation. Finally, it is concluded that the proliferation of hydroelectric plants in the Neotropical region might contribute to the expansion of these events and, consequently, increasing of impacts on fish conservation. We consider urgent the inclusion of this topic in the licensing processes for new hydropower projects by the environmental agencies.

The potential advantages of using a poly(HPMA) brush in urinary catheters: effects on biofilm cells and architecture

Infections related to bacterial colonization of medical devices are a growing concern given the socio-economical impacts in healthcare systems. Colonization of a device surface with bacteria usually triggers the development of a biofilm, which is more difficult to eradicate than free-floating or adhered bacteria and can act as a reservoir for subsequent infections. Biofilms often harbor Viable but nonculturable (VBNC) cells that are likely to be more resistant to antibiotic treatment and that can become active in more favorable conditions causing infection. Biofilm formation is dependent on different factors, chiefly the properties of the surface and of the surrounding medium, and the hydrodynamic conditions. In this work, the antifouling performance of a poly[N-(2-hydroxypropyl) methacrylamide] (poly(HPMA)) brush was evaluated in vitro in conditions that mimic a urinary catheter using Escherichia coli as a model organism. The results obtained with the brush were compared to those obtained with two control surfaces, polydimethylsiloxane (PDMS) (the most common material for catheters) and glass. A decrease in initial adhesion and surface coverage was observed on the brush. This antifouling behavior was maintained during biofilm maturation and even in a simulated post-bladder infection period when the reduction in total cell number reached 87 %. Biofilms were shown to adapt their architecture during that period and VBNC cells adsorbed weakly on the brushes and were completely washed away. Taken together, these results suggest that the use of the poly(HPMA) brush in urinary tract devices such as catheters and stents may reduce biofilm formation and possibly render the formed biofilms more susceptible to antibiotic treatment and with reduced infectivity potential.

Impact of modified diamond-like carbon coatings on the spatial organization and disinfection of mixed-biofilms composed of Escherichia coli and Pantoea agglomerans industrial isolates

This work investigated the effects of diamond-like carbon (DLC) coatings on the architecture and biocide reactivity of dual-species biofilms mimicking food processing contaminants. Biofilms were grown using industrial isolates of Escherichia coli and Pantoea agglomerans on bare stainless steel (SST) and on two DLC surface coatings (a-C:H:Si:O designated by SICON® and a-C:H:Si designated by SICAN) in order to evaluate their antifouling activities. Quantification and spatial organization in single- and dual-species biofilms were examined by confocal laser scanning microscopy (CLSM) using a strain specific labelling procedure. Those assays revealed that the E. coli isolate exhibited a higher adhesion to the modified surfaces and a decreased susceptibility to disinfectant in presence of P. agglomerans than alone in axenic culture. While SICON® reduced the short-term growth of E. coli in axenic conditions, both DLC surfaces increased the E. coli colonization in presence of P. agglomerans. However, both modified surfaces triggered a significantly higher log reduction of E. coli cells within mixed-species biofilms, thus the use of SICON® and SICAN surfaces may be a good approach to facilitate the disinfection process in critical areas of food processing plants. This study presents a new illustration of the importance of interspecies interactions in surface-associated community functions, and of the need to evaluate the effectiveness of hygienic strategies with relevant multi-species consortia.

Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

ABSTRACT. The relationships between the degree of dietary overlap and food availability, and implications for food selectivity of fish species were evaluated at floodplain lakes on the upper Paraná River floodplain, Brazil. The hypothesis tested were: i) species become less selective in lakes with high availability of food resources; and ii) species (interspecific) or individual (intraspecific) present higher food overlap in conditions of high availability of food resources. In general, with the results was observed that species become less selective when the environment provided higher availability of food resources. Interspecific overlap did not show a pattern when evaluating availability of food resources in the lakes. However, intraspecific overlap tended to be more accentuated in conditions of high availability of resource food.

Salinity does not alter the effectiveness of menthol as an anesthetic and sedative during the handling and transport of juvenile fat snook (Centropomus parallelus)

The effectiveness of menthol as anesthetic and sedative for fat snook (Centropomus parallelus) was tested at different salinities. In the first experiment, the fish were exposed to different concentrations of menthol (25, 37 and 50 mg L-1) in water at different salinities (0, 17 and 36 ppt). In the second experiment, the fish were transported for 10 hours in water with menthol at concentrations of 0, 3.7 and 7.4 mg L-1 under different salinities. Na+ and K+ ions from fish body and water were analyzed after transport. The optimal concentrations of menthol for a short handling period and surgical induction was 37 and 50 mg L-1, respectively, and these values were independent of salinity. After transport, neither mortality nor significant changes in ammonia or dissolved oxygen were observed between treatments at the different salinities. The nitrite levels were lower in freshwater than in brackish and saltwater, but did not change with mentol. The total body levels of Na+ increased with the salinity increase. Menthol is an effective anesthetic for handling of juvenile fat snook at different salinities. Menthol did not influence the measured water parameters and body ions, and it is not necessary for the transport of fat snook.

Fish reproductive guilds downstream of dams

Fish reproductive guilds were used to evaluate the responses of species with different reproductive strategies during two different periods of post-dam construction. The data used for the comparisons were collected in the upper Paraná River floodplain (Brazil), downstream of the Porto Primavera dam, 2 and 10 years after impoundment. The abundance (catch per unit effort, CPUE), species richness, evenness and structure of communities, all within reproductive guilds, were used to test the hypothesis that these metrics vary spatially and temporally. The influence of damming on species structure and the diversity of fish reproductive guilds varied spatiotemporally, and species with opportunistic reproductive strategies tended to be less affected. Conversely, long-distance migratory species responded more markedly to spatiotemporal variations, indicating that the ecosystem dynamics exert greater effects on populations of these species. Thus, the effects of a dam, even if attenuated, may extend over several years, especially downstream. This finding emphasizes the importance of maintaining large undammed tributaries downstream of reservoirs.

Taxonomic and numeric structure of Chironomidae (Diptera) in different habitats of a Neotropical floodplain

We characterized the local benthic Chironomidae by analyzing the numerical density, biomass, diversity index of Shannon-Wiener and dominance of larvae in the main channel of the Ivinhema River, in a secondary channel, in five lakes connected to the main channel and in five lakes without connection. Of the 68 taxa identified, Aedokritus sp., Tanytarsus sp., Chironomus strenzkei Fittkau, 1968 and Procladius sp.1 were found in all sampling sites and were considered morphospecies with greater of greatest ecological plasticity. Chironomus strenzkei Fittkau, 1968, contributed with the greatest biomass in the central region of lakes without connection, whereas Aedokritus sp. dominated in the littoral of lakes. The greater values of diversity indices in the littoral region of channels were due to the greater water flow and to the higher food availability in these areas. The dominance indices, by contrast, were greater on the central region of these environments. The littoral region has exclusive characteristics, representing habitats that could play important controlling in the numerical density and index diversity on the ecosystem, whereas that the biomass of benthic invertebrates in the central region in some biotopes would have different spatial probably according organisms drift.

Escherichia coli adhesion, biofilm development and antibiotic susceptibility on biomedical materials

The aim of this work was to test materials typically used in the construction of medical devices regarding their influence in the initial adhesion, biofilm development and antibiotic susceptibility of Escherichia coli biofilms. Adhesion and biofilm development was monitored in 12-well microtiter plates containing coupons of different biomedical materials--silicone (SIL), stainless steel (SS) and polyvinyl chloride (PVC)--and glass (GLA) as control. The susceptibility of biofilms to ciprofloxacin and ampicillin was assessed, and the antibiotic effect in cell morphology was observed by scanning electron microscopy. The surface hydrophobicity of the bacterial strain and materials was also evaluated from contact angle measurements. Surface hydrophobicity was related with initial E. coli adhesion and subsequent biofilm development. Hydrophobic materials, such as SIL, SS, and PVC, showed higher bacterial colonization than the hydrophilic GLA. Silicone was the surface with the greatest number of adhered cells and the biofilms formed on this material were also less susceptible to both antibiotics. It was found that different antibiotics induced different levels of elongation on E. coli sessile cells. Results revealed that, by affecting the initial adhesion, the surface properties of a given material can modulate biofilm buildup and interfere with the outcome of antimicrobial therapy. These findings raise the possibility of fine-tuning surface properties as a strategy to reach higher therapeutic efficacy.

96-well microtiter plates for biofouling simulation in biomedical settings

Microtiter plates with 96 wells are routinely used in biofilm research mainly because they enable high-throughput assays. These platforms are used in a variety of conditions ranging from static to dynamic operation using different shaking frequencies and orbital diameters. The main goals of this work were to assess the influence of nutrient concentration and flow conditions on biofilm formation by Escherichia coli in microtiter plates and to define the operational conditions to be used in order to simulate relevant biomedical scenarios. Assays were performed in static mode and in incubators with distinct orbital diameters using different concentrations of glucose, peptone and yeast extract. Computational fluid dynamics (CFD) was used to simulate the flow inside the wells for shaking frequencies ranging from 50 to 200 rpm and orbital diameters from 25 to 100 mm. Higher glucose concentrations enhanced adhesion of E. coli in the first 24 h, but variation in peptone and yeast extract concentration had no significant impact on biofilm formation. Numerical simulations indicate that 96-well microtiter plates can be used to simulate a variety of biomedical scenarios if the operating conditions are carefully set.

Macroscale versus microscale methods for physiological analysis of biofilms formed in 96-well microtiter plates

Microtiter plates with 96 wells have become one of the preferred platforms for biofilm studies mainly because they enable high-throughput assays. In this work, macroscale and microscale methods were used to study the impact of hydrodynamic conditions on the physiology and location of Escherichia coli JM109(DE3) biofilms formed in microtiter plates. Biofilms were formed in shaking and static conditions, and two macroscale parameters were assayed: the total amount of biofilm was measured by the crystal violet assay and the metabolic activity was determined by the resazurin assay. From the macroscale point of view, there were no statistically significant differences between the biofilms formed in static and shaking conditions. However, at a microscale level, the differences between both conditions were revealed using scanning electron microscopy (SEM). It was observed that biofilm morphology and spatial distribution along the wall were different in these conditions. Simulation of the hydrodynamic conditions inside the wells at a microscale was performed by computational fluid dynamics (CFD). These simulations showed that the shear strain rate was unevenly distributed on the walls during shaking conditions and that regions of higher shear strain rate were obtained closer to the air/liquid interface. Additionally, it was shown that wall regions subjected to higher shear strain rates were associated with the formation of biofilms containing cells of smaller size. Conversely, regions with lower shear strain rate were prone to have a more uniform spatial distribution of adhered cells of larger size. The results presented on this work highlight the wealth of information that may be gathered by complementing macroscale approaches with a microscale analysis of the experiments.

Percentage of Impervious Surface Soil as Indicator of Urbanization Impacts in Neotropical Aquatic Insects

Several recent studies have shown a strong correlation between the area of impervious surface soil (IS) and the insect community structure from urban streams. This study assessed whether this relationship is observed in Neotropical streams. We examined if an increased IS reduces the diversity and simplifies the trophic structure of the community of Ephemeroptera, Plecoptera, and Trichoptera. An IS threshold was detected between 1.6 and 9.3%, in which there is a change in the community, both in taxonomic richness and trophic structure. Among the 27 genera identified, only 15 occurred in streams with IS > 9%, while 24 genera were registered in streams with IS < 2%. The trophic guilds of predators and shredders were not observed in streams with high IS, decreasing the number of guilds in these streams from 5 to 3, compared with the streams with low IS. Three hypotheses with cumulative effect have been proposed to explain such variations. Based on the IS threshold verified, the creation of a mosaic of land use, where some subbasins would be sacrificed and others would be preserved, was suggested as a mitigation measure for the impacts caused by urbanization in the Neotropical aquatic insects' fauna.

Effects of the interannual variations in the flood pulse mediated by hypoxia tolerance: the case of the fish assemblages in the upper Parana River floodplain

The effects of the duration of the floods on abiotic variables and attributes of species tolerant and intolerant to hypoxia (STH and SIH respectively) were evaluated in rivers and lakes of the upper Paraná River. Fish were sampled once a year, in six sampling stations, during the high water period from 2000 to 2003. There were overall reductions in dissolved oxygen levels and increases in transparency of water in lakes in years of moderate floods. The duration of floods influenced species differentially based on their tolerance to hypoxia: in moderate floods, richness of STH increased and numerical abundance and biomass of SIH reduced significantly. Opposite relationships were detected between dissolved oxygen and the attributes of STH and SIH. Dissolved oxygen was the best predictor of variability of STH and SIH in years of moderate floods, whereas water transparency predicted significant amounts of STH in years of short floods. Being positively affected by dissolved oxygen reductions, STH seem to take advantages in persisting in seasonally harsh lentic habitats. The incorporation of abiotic data as well the differential tolerance of species to hypoxia would improve further investigations of the effects of interannual variations in the flood pulse on tropical fish assemblages

A barrier to upstream migration in the fish passage of Itaipu Dam (Canal da Piracema), Paraná River basin

The majority of the fish passages built in the Neotropical region are characterised by low efficiency and high selectivity; in many cases, the benefits to fish populations are uncertain. Studies conducted in the Canal da Piracema at Itaipu dam on the Parana River indicate that the system component designated as the Discharge channel in the Bela Vista River (herein named Canal de deságue no rio Bela Vista or CABV), a 200 m long technical section, was the main barrier to the upstream migration. The aim of this study was to evaluate the degree of restriction imposed by the CABV on upstream movements of Prochilodus lineatus and Leporinus elongatus, Characiformes. Fish were tagged with passive integrated transponders (PIT tags) and released both downstream and upstream of this critical section. Individuals of both species released downstream of the CABV took much more time to reach the upper end of the system (43.6 days vs. 15.9 days), and passed in much lower proportions (18% vs. 60.8%) than those tagged upstream of this component. Although more work is needed to differentiate between fishway effects and natural variation in migratory motivation, the results clearly demonstrate passage problems at the CABV.

Estimates of population parameters and consumption/biomass ratio for fishes in reservoirs, Paraná State, Brazil

Consumption, natural mortality, and growth are important parameters for the construction for both fisheries and ecosystems models. We estimated k (growth constant of the von Bertalanffy's function), Loo 1(asymptotic length), Woo (asymptotic weight), Ar (caudal fin index), M (natural mortality), and Q/B (consumption/biomass ratio) for several fish species inhabiting reservoirs. We explored possible relationships among these parameters for 135 fish species sampled in thirty reservoirs in the State of Paraná, southern Brazil. Maximum length (Lmax) varied from 2.60 to 79.00 cm, Loo from 2.73 to 85.05 cm, Woo from 0.23 to 9,490.26 g, k from 0.01 to 2.38 yr-1, Ar from 0.03 to 3.60, M from 0.16 to 2.82 yr-1, and Q/B from 3.31 to 67.18. Significant correlations were observed between most pairs of parameters, except for Ar and k, Ar and Loo , and for M and Q/B. The estimates presented here may be useful for constructing Ecopath models, both in Brazil and other tropical regions, where the use of ecosystem modeling is growing.

The ichthyofauna of drifting macrophyte mats in the Ivinhema River, upper Paraná River basin, Brazil

We describe the fish assemblages associated with drifting macrophyte mats and consider their possible role as dispersal vectors in the Ivinhema River, a major tributary of the upper Paraná River, Brazil. Fish associated with drifting mats were sampled in the main river channel during January and March 2005, when the wind and/or the increased water level were sufficient to transport macrophyte stands. Fish in the drifting mats were sampled with a floating sieve (4 m long x 2 m wide x 0.6 m high, and 2 mm mesh size). In the laboratory, larvae, juvenile, and adult fish were counted and identified to the lowest possible taxonomic level. In four drifting macrophyte mats we captured 218 individuals belonging to at least 28 species, 17 families, and 6 orders. Aphyocharax dentatus, Serrasalmus spp., and Trachelyopterus galeatus were the most abundant taxa associated with the mats, but species richness ranged from 6 to 24 species per mat. In addition, 85% of the total number of individuals caught was larvae and juveniles. Although preliminary and based on limited samples, this study of drifting macrophyte mats was the first one in the last unregulated stretch of the Paraná River remaining inside Brazilian territory, and alerts us to the potential role of macrophytes mats as dispersers of fish species in the region.

Cage culture with tilapia induces alteration in the diet of natural fish populations: the case of Auchenipterus osteomystax

Fish rearing in cages installed in reservoirs has developed rapidly in Brazil over the last decade. However, this type of aquaculture induces some changes in the environment because of the high quantity of nutrients released into the surroundings. This study evaluated trophic changes resulting from these nutrient inputs into the diet, feeding activity and nutritional condition of Auchenipterus osteomystax, an insectivore that alternatively feeds on zooplankton. Fish were sampled with gillnets in two tilapia (Oreochromis niloticus) experimental caging aquaculture areas of the Rosana reservoir (Paranapanema River), at different distances from the cages. Samplings were carried out for 90 days (before the cages were installed and 30 and 60 days after installation). Diet analysis was based on 250 stomach contents evaluated with occurrence and volumetric methods, combined into a Feeding Index. The spatial and temporal variations in feeding activity were inferred by the stomach repletion index (stomach weight). The relative condition factor was used to evaluate the individual nutritional condition of the sampled fish. Insects and zooplankton accounted for more than 85% of the diet in any sample. Insects predominated before caging culture started and at the end of the sampling period, whereas zooplankton predominated 30 days after caging began. The repletion index increased at 30 days after caging in both areas when the condition factor was the lowest, with some recovery at the end of this period. The input of nutrients near caging areas caused a short elevation in zooplankton availability, which promoted changes in the diet of this opportunist species, increasing its feeding activity. However, these changes appeared to be unsustainable due to the poor nutritional condition of the individuals.

Age, growth, mortality and yield per recruit of the dourado Salminus brasiliensis, Corumbá Reservoir, Goiás State, Brazil

In order to evaluate the fate of the migratory species dourado Salminus brasiliensis in the first years of impoundment in Corumbá Reservoir we estimated age, growth, mortality and yield per recruit. Samplings were carried out monthly in Corumbá Reservoir and its main tributaries (Goiás State) from March 1998 to February 1999 using gillnets. After one year of impoundment, age was estimated from scales and the maximum number of rings was six for males and five for females. Rings are formed annually in May and June. The asymptotic length and growth rate for males and females were 37.1 cm and 0.77 and 56.6 cm and 0.52, respectively. A dominance of juveniles was verified in the reservoir and its tributaries. The instantaneous total mortality rate (Z) was 1.59 and the annual total mortality rate (A) was 79.6%. The highest yield per recruit (1200g) and the highest average weight (1900g) were obtained in simulations with low values of fishing (F) and natural (M) mortalities. Based on the above information we describe the Corumbá Reservoir impoundment has influenced the growth of the dourado. As regards this study, we recommend that the fishing effort not be applied during the trophic upsurge period and that the monitoring of the dourado assemblage continue. Fishery programs management for this species should be carried out with subsequent monitoring involving efficient communication, realistic practices and involvement of fisher organizations.

Fish larvae from the upper Paraná River: do abiotic factors affect larval density?

The purpose of this study was to evaluate the role of abiotic factors on fish larvae occurrence. Samplings were carried out monthly at 12 stations (grouped in four areas) in the Amambaí, Ivaí and Paraná rivers and in the Itaipu Reservoir (upper Paraná River basin), from October 1994 to January 1995 (spawning season). Simultaneously, we obtained water temperature, pH, electrical conductivity, dissolved oxygen, water level, water velocity, and rainfall. Principal Component Analyses (PCA) and Detrended Correspondence Analyses (DCA) were applied to summarize abiotic and larvae density data, respectively. Amambaí River differed significantly from the other areas in relation to abiotic factors. Itaipu Reservoir differed significantly from the other areas considering species composition, and the Ivaí River also differed from the Paraná River. The relationship among PCA and DCA axes were significant, indicating that abiotic factors do influence larva. For example: Leporinus elongatus prefered the Amambaí River, Hypophthalmus edentatus, Plagioscion squamosissimus, and Hoplias aff. malabaricus the Itaipu Reservoir, and Pimelodus maculatus, Auchenipterus osteomystax and Iheringichthys labrosus the Ivaí River. We suggest that species selected some abiotic factors characteristic to a given environment as spawning grounds.

Environmental factors related to entry into and ascent of fish in the experimental ladder located close to Itaipu Dam

We evaluated the seasonality of the ascent of fish in an experimental ladder located close to Itaipu Dam, and its relationships to reproduction, temperature, river level and discharge. Samplings of fish and measurements of abiotic factors were performed from February, 1995 through January, 1997, in two resting pools of the ladder. Pool A was located 10 m above the mean level of the Paraná River; Pool B was located at the upper end of the ladder, at a height of 27 m. Autoregressive models were used to remove the temporal dependence between observations. Residuals of the models were used to relate, using Pearson's correlation coefficient, the densities of fish to the environmental variables. Clear patterns of seasonality were observed for temperature. River level, turbine discharge and spillway discharge, although they showed no clear seasonal dynamics, were time-dependent, because the autocorrelation coefficients for different k values were significant. In the samples of larger-sized fish, 23 species were recorded during the two years of study. Most of the individuals were in a non reproductive state, and about 90% of the individuals belonged to only six species. The temporal variability in total abundance, considering all species, indicated a pattern of seasonal variation; high abundances occurred from October through February (75%) and in Pool A (61% of the 1343 individuals sampled). Low abundances were recorded during winter, with the correlogram of total density confirming this tendency. In the samples of smaller-sized species, six species were recorded, with all six present in both pools, but more frequent in the first pool (64%). Bryconamericus stramineus comprised 99% of the total numbers of smaller fish in the samples. The total abundance of small species showed different temporal patterns of seasonal variation in the two years of study.

The Canal da Piracema at Itaipu Dam as a fish pass system

The Canal da Piracema is the longest (nearly 10 km) fish pass system in the world. The construction of this fish pass was somehow controversial, because it connected two distinct ichthyofaunistic provinces. This study evaluated the ichthyofauna present in the Canal da Piracema and the abundance and distribution of long-distance migratory fish species along this fish pass system (evaluated possible selectivity). The Canal da Piracema was shown to be difficult to sample because of its environmental heterogeneity: artificial ponds, ladders and nature-like fish pass. To solve this problem, we used several fishing gears, adequate for the several biotopes present (unstructured and structured littoral were sampled with seining nets and electrofishing; lentic were sampled with gillnets and longlines (deeper areas); and rapid water areas were sampled with cast nets). The ichthyofauna of the Canal da Piracema followed the pattern for South America and the Paraná River, with a predominance of Characiformes and Siluriformes. The most representative families were Characidae, Anostomidae, Pimelodidae and Loricariidae. We captured 116 species (17 were long-distance migratory) during the period studied. Small-sized species were predominant in unstructured and structured littoral areas, especially Bryconamericus exodon and Apareiodon affinis.The most abundant species was Hypostomus spp. in lentic areas, followed by Iheringichthys labrosus. Hoplias aff. malabaricus predominated in deeper lentic areas. Long-distance migratory species were abundant in rapid waters; they were Prochilodus lineatus and Leporinus elongatus. The sharp reduction in the number of species, including migratory ones, is an indication that the Canal da Piracema is selecting the species that ascend it. Therefore, the search for information on the efficiency of the various fish passes present in the Canal da Piracema is fundamental, to facilitate upward movements of fish. If this is reached, this polemic fish pass has the potential to contribute to the conservation of fish stocks in Itaipu Reservoir and upstream stretches, because of the presence of spawning and development (nurseries) areas for migratory species.

Utilization of the fish ladder at the Engenheiro Sergio Motta Dam, Brazil, by long distance migrating potamodromous species

Utilization of the fish ladder installed at the Engenheiro Sergio Motta Dam (also known as Porto Primavera) on the Paraná River, Southern Brazil, by long-distance migrating potamodromous species (sampling Protocol I), and ascending and descending movements (Protocol II) were evaluated. Three pools along the fish ladder (designated as lower, middle, and upper) were sampled monthly between December, 2004 and March, 2005 to determine the abundance of species in the ladder. The ascending and descending movements of the species in the ladder were also analyzed in the same period. In the samples for both protocols, 37 species representing 17 families and 5 orders (Characiformes, Siluriformes, Perciformes, Gymnotiformes, and Myliobatiformes) were recorded. Characiformes were represented by 21 species. Long- distance migratory species (11 species) predominated in the ladder (60% of the total number of individuals), with high abundance of Rhinelepis aspera (5645 individuals). For protocol I, mean abundance varied greatly among the months and pools, with lowest values in December and March for all pools, and highest in January for the lower pool due to high capture of R. aspera. Fish abundance declined from the lower to the upper pool, especially for R. aspera and Rhaphiodon vulpinus. For Protocol II, 17 species were recorded ascending the ladder, where Astyanax altiparanae and Leporinus friderici were the most abundant species (684 and 111 individuals, respectively). However, 18 species showed descending movements, with high captures of Metynnis maculatus and A. altiparanae (339 and 319 individuals, respectively). Twelve species (52%) moved in both directions, and among the seven migratory species sampled, four were recorded ascending and descending, and three species only ascending the ladder. The fish ladder appears to selectively favor species with high swimming capabilities. A discussion is presented on the requirements for future research on attraction to the fish ladder entrance, downstream movements, fish utilization of the ladder, and impacts on spawning and rearing habitat both upstream and downstream of the dam.

Modeling energy flow in a large Neotropical reservoir: a tool do evaluate fishing and stability

Recently, there is an increasing perception that the ecosystem approach gives important insights to support fisheries stock assessment and management. This paper aims to quantify energy flows in the Itaipu Reservoir (Brazil) and to simulate increase of the fishing effort of some species, using Ecopath with Ecosim software, which could allow inferences on stability. Therefore, two steady-state Itaipu models were built (1983-87 and 1988-92). Results showed that: a) there are no differences between models, and results on aging trends do not vary over time indicating that fishery does not alter the ecosystem as a whole; b) results of fisheries simulations are approximate to mono-specific stock assessment for the same species and periods; c) many authors believe that tropical ecosystems are environments where biotic and abiotic oscillations are annual and sometimes unexpected, but the results found for the Itaipu Reservoir indicate that stability was met after 16 years.

Transportation of juvenile tambaqui (Colossoma macropomum) in a closed system

The objective of this study was to investigate the effect of density, duration and the use of additives to the water during the transportation of juvenile tambaqui (Colossoma macropomum) and use of this data to establish a safe transportation protocol for the species. The tested products and dosages were: salt (1000, 2000 and 3000 mg/L), gypsum (100, 300 and 500 mg/L) and benzocaine (10, 20 and 30 mg/L). Fish were transported in closed systems (plastic bag) at different densities and time periods of up to 24 h. Fish survival (FS) and water quality parameters were monitored immediately after transportation. The remaining fish were kept in floating cages in order to evaluate mortality which occurred up to 96 h after transportation (S96). The best fish density, additives dosages and time period of the transportation was estimated with a general linear model. The effect of the condition factor on FS and S96 was also evaluated. As expected, FS and S96 were significantly related to time and density. FS but not S96, were also were significantly related to treatment. FS with gypsum treatment was not different from controls and FS with table salt and benzocaine treatments were significantly reduced. The condition factor was not related to either FS or S96. FS was inversely correlated with carbon dioxide concentration. It was concluded that the additives did not improve fish transportation survival. Linear models were developed to predict the best transportation densities as a function of time.

Factors influencing Serrapinnus notomelas (Characiformes: Characidae) populations in upper Paraná river floodplain lagoons

Identification of variables that influence fish populations is one of the main challenges in ecology. To explore this, data were collected quarterly from February 2000 to November 2001 using seines, along the shore of four isolated lagoons of the upper Paraná River floodplain. Serrapinnus notomelas was selected to assess the effect of abiotic and biotic variables using indirect gradient analysis. Abiotic variables were summarized by principal components analysis (PCA) and then the scores of the axis retained for interpretation were correlated with abundances of S. notomelas. Variables that best explained S. notomelas abundance were surface area of the lagoon, total suspended solids and Secchi depth (these last two, indirectly linked to predation). The most relevant biotic variable that determined population size of S. notomelas was predation.

Metabolic adjustments in two Amazonian cichlids exposed to hypoxia and anoxia

The effects of graded hypoxia on the physiological and biochemical responses were examined in two closely related species of cichlids of the Amazon: Astronotus crassipinnis and Symphysodon aequifasciatus. Ten fish of each species were exposed to graded hypoxia for 8 h in seven oxygen concentrations (5.92, 3.15, 1.54, 0.79, 0.60, 0.34, and 0.06 mg O(2) L(-)(1)), with the aim to evaluate hypoxia tolerance and metabolic adjustments, where plasma glucose and lactate levels, hepatic and muscle glycogen contents, and maximum enzyme activities (PK, LDH, MDH and CS) in skeletal and cardiac muscles were measured. Another experimental set was done to quantify oxygen consumption (MO(2)) and opercular movements in two oxygen concentrations. Hypoxia tolerance differed between the two species. Astronotus crassipinnis was able to tolerate anoxia for 178 min while S. aequifasciatus was able to withstand 222 min exposure in deep hypoxia (0.75 mg O(2) L(-)(1)). Suppressed MO(2) was observed during exposure to 0.34 (A. crassipinnis) and 0.79 mg O(2) L(-)(1) (S. aequifasciatus), while opercular movements increased in both species exposed to hypoxia. Higher levels of muscle and liver glycogen and larger hypoxia-induced increases in plasma glucose and lactate were observed in A. crassipinnis, which showed a higher degree of hypoxia tolerance. Changes in enzyme levels were tissue-specific and differed between species suggesting differential abilities in down-regulating oxidative pathways and increasing anaerobic metabolism. Based on the present data, we conclude that these animals are good anaerobes and highly adapted to their environment, which is allowed by their abilities to regulate metabolic pathways and adjust their enzyme levels.

Fish assemblages of tropical floodplain lagoons: exploring the role of connectivity in a dry year

Irregular rainfall and pronounced reductions of the hydrometric level in the year 2000 resulted in drastically altered hydrological connectivity of lentic environments in the upper Paraná River floodplain. The objective of the present work was to examine spatial and temporal patterns of fish assemblage attributes and structure in relation to limnological variables associated with hydrological connectivity. Fish were collected quarterly by seining in the marginal areas of 15 lagoons belonging to two biotopic categories (connected and disconnected). Variation in assemblage composition reflected the degree of hydrological connectivity. Values of assemblage attributes (species richness, density and biomass) were significantly lower in connected lagoons than in disconnected lagoons. Significantly higher values of species richness and biomass were recorded in November than in August. Rare species had the greatest effect on observed patterns in fish assemblage ordination (DCA). Observed patterns of variation in assemblage attributes were directly correlated with factors related to hydrological connectivity, such as depth, resources (zooplankton and chlorophyll a) and nutrients (total phosphorus).

[Illness, hospitalization and anxiety: an approach to mental health]

With the purpose of completely approaching the patient in the hospital, this research had the goal to identify the generating factors of the of anxiety patient and how they express their uneasiness towards the illness and the hospitalization the data were collected from april/may/96 with adults in a school-hospital and was based on a guide for observation of the anxieting situations and in an interview guide. We found out that the patients' major concerns were: Knowing if their illness has aure, how long they will be there, their and the support of the family. They get sadder at night and in the afternoon, when the staff is reduced, there is more silence and they feel lonely. Only a small percentage of them have the consistent information about the disease and treatment, however, the hospital is mainly identified as a good place for the possibility of cure, good assistance and food. Witnessing the suffering and the dying risk of the neighbour, be discharged, exams and treatment procedures suspended on cancelled, bling communicated of the necessity of bling operated on that the disease doesn't have a cure, were the anxieting factors that were remanked not only in the immediate sections, but also in the late ones of the anxieting situations, prevail passive attitudes such as sadness, crying, depression and negativism. We concluded that the psychic and emotional conditions of the patients in the hospital have to be taken on consideration on hospitals emphasizing a comsiete approach, with special care of the speed of the actions and the consistence of the information given to the patient about their health and treatment.