Caracterização das assembléias de peixes do rio Taquari, tributário da represa de Jurumirim (Alto rio Paranapanema, SP): diversidade e atributos ecológicos

The aim of this study was to characterize the composition, diversity and ecological attributes of fish assemblages of Taquari River, one of the main tributaries of Jurumirim Reservoir, Upper Paranapanema River, SP. Samplings were carried out every other three months between April, 2011 and February, 2012, using gill nets, trawl net and sieve to capture the fishes with standardized effort. It was established four sampling sites (upper, middle, low and dam) with different physical characteristics. It was sampled 4.598 specimens belonging to five orders, 16 families, 31 genus, and 41 species. A longitudinal pattern related to ecological attributes of fish assemblages was characterized, in which the upper stretch, the furthest from the dam floodplain, showed greater abundance and species richness. However, these indexes tend to diminish toward the stretches located downstream. This study contributes to occurrence records of nonnative species, with greater abundance and biomass of Cichla kelberi, an invasive piscivorous species, in the lentic stretch indicating patterns of spatial and temporal variations differentiated among the stretches sampled. Dammed waters jeopardize species richness of natural aquatic ecosystem overtime, due to the reduction of areas that are favorable to life cycle success of local species. Therefore, the study emphasizes the importance of large tributaries upon maintenance of fish diversity of large river basins with several dammed stretchesO objetivo deste trabalho foi caracterizar a composição, diversidade e atributos ecológicos das assembleias de peixes do rio Taquari, um dos principais tributários da represa de Jurumirim, Alto rio Paranapanema, SP. Foram realizadas coletas trimestrais entre abril de 2011 a fevereiro de 2012, utilizando-se de redes de espera, arrasto e peneirão para captura dos peixes com esforço padronizado. Foram estabelecidos quatro trechos amostrais (alto, médio, baixo e represa) com diferentes características físicas. Foram coletados 4.598 espécimes de peixes pertencentes a cinco ordens, 16 famílias, 31 gêneros e 41 espécies. Um padrão longitudinal relacionado com os atributos ecológicos das assembleias de peixes foi caracterizado, no qual o trecho Alto, mais distante da planície de alagamento da represa, apresentou maior abundancia e riqueza de espécies. À medida que se avança para os trechos à jusante, esses índices tendem a diminuir. Este trabalho contribui para o registro de ocorrência de espécies não nativas, com destaque à espécie piscívora invasora Cichla kelberi no trecho de ambiente lêntico. Os resultados indicam que ocorrem padrões de variações espaciais e temporais nas assembleias de peixes entre os trechos amostrados. Portanto, este estudo sugere que as águas represadas compromete a riqueza de espécies de ecossistemas aquáticos naturais, devido à redução ao longo do tempo das áreas favoráveis ao sucesso do ciclo de vida das espécies locais. Este trabalho enfatiza a importância de grandes tributários na manutenção da diversidade de peixes de grandes bacias hidrográficas, já com diversos trechos represado

Influência de uma piscicultura em tanquesrede na dieta e atributos biológicos de Galeocharax knerii na represa de Chavantes, Brasil

The aim of the present study was to evaluate the diet and biological attributes of the population of Galeocharax knerii residing near net cage fish farming activities in the Chavantes reservoir (Paranapanema River, Brazil) to check their possible impacts. Samples were collected from two populations: one near the net cages (NC) and one from an area not influenced by these cages denominated the reference site (RS). Monthly sampling was carried out from March 2008 to February 2009. Fish were caught with a standardized effort using gill nets deployed for 14 hours. The alimentary index (AI) and degree of repletion (RD) were calculated to determine diet composition. Analyses of the sex ratio and the gonadosomatic index (GSI) were also performed. The calculations of AI revealed that fish wastes constituted the most frequent food item in the diet in both study areas (NC = 70.43; RS = 87.55), followed by the consumption of Apareiodon affinis (AI = 29.56), which was abundant near the NC, and prawn at the reference site (AI = 12.28). The sex ratio differed from 1:1 and mature individuals were only found in the population near the NC. The findings demonstrate that G. knerii indirectly benefits from the input of organic matter, using small fish as its main food resource. We conclude that the activities of fish farming influence diet and biological attributes of the species G. knerii, evidenced mainly by higher feeding activity, numerical abundance and biomass in the area of the cages

Biology, ecology and biogeography of the South American silver croaker, an important Neotropical fish species in South America

The South American silver croaker is a popular fish that has recently received substantial attention from scientists, mainly due to its importance as source of animal protein and as a key fisheries species. However, little is known about the conditions that explain its historical and current spatial distribution, both in its native habitat and where it is a successful invasive species. The aim of the present study was to explore the ecological information available for this species, to then critically examine ecological theories related to the conditions underpinning its success. To this end, an exhaustive literature search was conducted with the immediate aim of investigating whether the success of South American silver croaker was driven by species-climate or species–human interactions. The non-native populations were found to occupy climate niche spaces different from those observed in their native ranges. In addition, it was clear that humans played a role in facilitating the large-scale dispersion of silver croaker, and assisted as agents of impact driving the observed current and, probably, the future spatial distribution, which we can predict from our data and from the pattern of propagule pressure. Overall, the current biogeography of this species illustrates how the construction of dams, along with the introduction and stocking of non-native species, overfishing and other human activities can alter fish populations and assemblages. Such processes can reduce native species, increase the abundance and distribution of invasive species, as well as cause changes in life-history traits and genetic variability, all with long-term socioeconomic consequences. © 2018, Springer International Publishing AG, part of Springer Nature

Tyramine exerts hypolipidemic and anti-obesity effects in vivo

Obesity and dyslipidemia are conditions often associated with cardiovascular risk, inflammation, oxidative stress, and death. Thus, a new approach has been highlighted to promote research and development of pharmacological tools derived from natural sources. Among the most widely studied groups of substances, polyphenols such as tyramine stand out. This study investigated hypolipidemic and anti-obesity properties of tyramine. Oral toxicity evaluation, models of dyslipidemia and obesity were used. To induce dyslipidemia, Poloxamer-407 (P-407) was administered intraperitoneally. In the hypercholesterolemic and obesity model, specific diet and oral tyramine were provided. After 24h of P-407 administration, tyramine 2 mg/kg (T2) decreased triglycerides (TG) (2057.0 ± 158.5 mg/dL vs. 2838 ± 168.3 mg/dL). After 48h, TG were decreased by T2 (453.0 ± 35.47 vs. 760.2 ± 41.86 mg/dL) and 4 mg/kg (T4) (605.8 ± 26.61 760.2 ± 41.86 mg/dL). T2 reduced total cholesterol (TC) after 24h (309.0 ± 11.17 mg/dL vs. 399.7 ± 15.7 mg/dL); After 48h, 1 mg/kg (T1) (220.5 ± 12.78 mg/dL), T2 (205.8 ± 7.1 mg/dL) and T4 (216.8 ± 12.79 mg/dL), compared to P-407 (275.5 ± 12.1 mg/dL). The treatment decreased thiobarbituric acid reactive substances and nitrite in liver, increased superoxide dismutase, reduced the diet-induced dyslipidemia, decreasing TC around 15%. Tyramine reduced body mass, glucose, and TC after hypercaloric feed. Treatment with 5 mg/L (0.46 ± 0.04 ng/dL) and 10 mg/L (0.44 ± 0.02 ng/dL) reduced plasma insulin (1.18 ± 0.23 ng/dL). Tyramine increased adiponectin at 5 mg/L (1.02 ± 0.02 vs. 0.83 ± 0.02 ng/mL) and 10mg/L (0.96 ± 0.04 ng/mL). In conclusion, tyramine has low toxicity in rodents, has antioxidant effect, reduces plasma triglycerides and cholesterol levels. However, further studies should be conducted in rodents and non-rodents to better understand the pharmacodynamic and pharmacokinetic properties of tyramine