The B chromosomes of the African cichlid fish Haplochromis obliquidens harbour 18S rRNA gene copies

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

Comparative chromosome mapping of repetitive sequences. Implications for genomic evolution in the fish, Hoplias malabaricus

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

Chromosome spreading of associated transposable elements and ribosomal DNA in the fish Erythrinus erythrinus. Implications for genome change and karyoevolution in fish

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

Isolation and characterization of microsatellite loci in the Neotropical fish Astyanax altiparanae (Teleostei: Characiformes) and cross-species amplification

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

Integrating cytogenetics and genomics in comparative evolutionary studies of cichlid fish

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

Aquatic insects as the main food resource of fish the community in a Neotropical reservoir

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

Influence of a cage farming on the population of the fish species Apareiodon affinis (Steindachner, 1879) in the Chavantes reservoir, Paranapanema River SP/PR, Brazil

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

Three sympatric karyomorphs in the fish Astyanax fasciatus (Teleostei, Characidae) do not seem to hybridize in natural populations

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

GFAAS Determination of Zinc in Fish Feed and Feces Using Slurry Sampling

This paper presents a simple, fast, and sensitive method to determine zinc in samples of feces and fish feed by electrothermal atomic absorption spectrometry through the direct introduction of slurries of the samples into the spectrometer's graphite tube. The procedure is based on the injection of 10 mu L of an acidified aqueous solution containing 0.50% w/v of feces or feed and 0.50% v/v HNO(3) into graphite tube. The limits of detection and quantification calculated for 20 readings of the blank of the standard slurries (0.50% w/v of feces or feed devoid of zinc) were 0.04 and 0.13 mu g L(-1) for the standard feces slurries and 0.05 and 0.17 mu g L(-1) for the standard feed slurries. The proposed method was applied in studies of digestibility of zinc in different fish feeds, and their results proved compatible with that obtained from samples mineralized by acid digestion using microwave oven.

Independent and interactive effects of a top and an intermediate fish species on the food web structure of a tropical stream

Two fish species, one top predator (Imparfinis mirini) and one intermediate detritivorous species (Hisonotus depressicauda), were experimentally manipulated to evaluate their relative importance in structuring the periphytic community, as well as their effects on the other trophic levels. An enclosure experiment was conducted in the Potreirinho creek, a second order tributary of Paranapanema River, SE Brazil. Five treatments were used: enclosure of the predator species. enclosure of the detritivorous species, enclosure of both together, exclusion of all fish species (closed control cage), and cage open to all fish community, (open control). Through direct and indirect effects, I. mirini, when alone gave rise to a trophic cascade that resulted in a positive effect on algal resources. Through direct effects, H. depressicauda. when alone, reduced the amount of organic matter, resulting in a positive indirect effect on algae. In addition, when the two species were enclosed together, only the effects determined by the detritivorous species were present. The results indicate the important role of the intermediate detritivorous species in the maintenance of the composition and trophic structure of the analyzed community by reducing the effects caused by the top predator.

Genetic structure of the ornamental tetra fish species Piabucus melanostomus Holmberg, 1891 (CHARACIDAE, IGUANODECTINAE) in the Brazilian Pantanal wetlands inferred by mitochondrial DNA sequences

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

Induction of micronucleus and nuclear alterations in fish (Oreochromis niloticus) by a petroleum

In this study, micronucleus and nuclear alterations tests were performed on erythrocytes of Oreochromis niloticus (Perciformes, Cichlidae) in order to evaluate the water quality of the Atibaia river, in an area that receives effluents discharge of a petroleum refinery and also to evaluate the effectiveness of the treatments used by the refinery. Water samples were collected in five different sites related with a refinery from São Paulo State, Brazil. For the micronucleus and nuclear alterations tests, O. niloticus specimens were exposed for 72 h to the water samples and in pure ground water (negative control). The results herein obtained indicated that the treatments used by the refinery diminished the cytogenetic damage; however they were not fully effective, since the final mill has induced damages in the genetic material of the test organism. (C) 2008 Elsevier B.V. All rights reserved.

Natural and artificially-induced habitat complexity and freshwater fish species composition

The effects of habitat complexity, induced by construction of artificial reefs, on the fish assemblages in the Barra Bonita reservoir, Brazil, and in the lotic zone immediately below the dam were studied. Four artificial reefs were constructed in each habitat at variable distances from the shore. Multiple correspondence analysis showed that the factors distance from the shore and type of habitat were determinants for the group formation, and artificial reefs had a lesser effect. Fish species composition was about the same at locations with and without reefs.

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.