Food resources partitioning among sciaenid fishes (Perciformes, Sciaenidae) of the Flamengo bay, Ubatuba, southeastern Brazil

The determination of the diet and feeding habits is one of the principal aspects of the study on fish biology, as feeding is a basic process and its study is necessary for the understanding of the populations' dynamic and ecology. The Sciaenidae family has a significant occurrence in the bay's demersal ichthyofauna, constituting an important fishing resource. The goal of this work was to analyze how the partitioning of available food resources takes place among the ten sciaenid species which live in the Flamengo Bay. One single survey, consisting of three trawls, was carried out with a fishing boat equipped with two otter-trawl. Diet analysis showed that all species are exclusively carnivore, using several items as food, but crustaceans are the main food ingested. The use of the ''Proportional Overlap Index'' showed possible overlapping between six couples of species but in the majority of cases, morphologic differences between these species, such as the mouth position, probably determine different foraging strategies.

Mutagenic and genotoxic effects of the Atrazine herbicide in Oreochromis niloticus (Perciformes, Cichlidae) detected by the micronuclei test and the comet assay

Atrazine is the triazinic herbicide most found in the rural aquatic environments due to its extensive use and its stability in such places. The mutagenicity and the genotoxicity of different concentrations of the Atrazine herbicide were determinated by the micronucleus test and the comet assay, using Oreochromis niloticus as test-system. The tested concentrations of Atrazine herbicide were 6.25, 12.5 and 25 mu g/L, both for the micronuclei test and for the comet assay. The results showed a significant rate of micronuclei and nuclear abnormalities for all the tested concentrations of Atrazine herbicide. For the comet assay, we also observed results significantly different from the control in 6.25, 12.5 and 25 mu g/L concentrations. Due to these results, we could infer that such herbicide may be dangerous to the lives of those organisms exposed to it. (c) 2007 Elsevier B.V. All rights reserved.

The ultrastructure of the pre-meiotic and meiotic stages of spermatogenesis in Plagioscion squamosissimus (Teleostei, Perciformes, Sciaenidae)

Spermatogenesis of 'corvina' P. squamosissimus starts from a stem cell that gives rise to germ cells. These cells are enveloped by Sertoli cells, forming cysts. The germ cells in the cysts are all at the same stage of development and are interconnected by cytoplasmic bridges. Spermatogonia are the largest germ cells. In the cysts, these cells differentiate into primary spermatogonia and secondary spermatogonia. The primary spermatogonia are isolated in the cyst and give rise to the secondary spermatogonia. After several mitotic divisions, they produce spermatocytes I, which can be identified by synaptonemal complexes in the nucleus. The spermatocytes I enter the first phase of meiosis to produce the spermatocytes II. These are not very frequently seen because they rapidly undergo a second phase of meiosis to produce spermatids.

Relação peso-comprimento e fator de condição para Cichla cf. ocellaris e Cichla monoculus (Perciformes, Cichlidae) no reservatório de Volta Grande, Rio Grande - MG/SP

The aim of this paper was to analyze the length-weight relationship and the condition factor of two species of cichlids (Cichla cf. ocellaris and Cichla monoculus) (Perciformes, Cichlidae) that were inducted in Volta Grande Reservoir, Rio Grande. There was no difference in the length-weight relationship between the sexes for Cichla cf. ocellaris and Cichla monoculus. The allometric condition factor showed a fall in the spring and another smaller one in the winter. It happens when these fishes change their feeding activity. In the spring all the reproductive behavior are developed and, in the winter, there is a shortage of prey. The variation of the relative condition factor followed the variation of the allometric condition factor due to the low contribution of the gonads weight and the small amount of accumulated fat in the total weight. The length distribution, length-weight relationship and condition factor of these fishes vary in accordance with the time of introduction into the reservoir, the characteristics of the ecosystem as well as the interactions among the species at these sites.

Revision of the South American freshwater genus Plagioscion (Teleostei, Perciformes, Sciaenidae)

The South American freshwater sciaenid genus Plagioscion is reviewed. Five of the 15 nominal species assigned to the genus are considered to be valid: Plagioscion squamosissimus, widely distributed in Atlantic drainages east of the Andes; P. auratus from the Río Orinoco and Río Amazonas basins; P. magdalenae from the Río Magdalena and Río Amazonas basins; P. ternetzi from the lower Río Paraná, Río Paraguay and Rio Uruguay basins; and P. montei from the Río Amazonas basin. Copyright © 2005 Magnolia Press.

Schooling behavior of Mugil curema (Perciformes: Mugilidae) in an estuary in southeastern Brazil

Schools of mullets, Mugilidae, are abundant in estuaries and shallow marine waters. We report on the schooling behavior of juvenile white mullet, Mugil curema, in the estuary of the Canto da Paciência stream, in Ubatuba, southeastern Brazil. Schools of small fish (15 to 35 mm TL) were composed of a larger number of individuals (up to a hundred individuals), and were found feeding mainly in shallow nearshore waters, whereas schools of larger fish (40 to 100 mm TL) were observed only in deeper waters. Three patterns of swimming were observed for the schools: stationary feeding, slow movement while searching for food, and rapid displacement. The variations observed in school structure and behavior seem to be related to the balance between predation risk and increasing food intake. Copyright © 2007 Sociedade Brasileira de Ictiologia.

Relação peso-comprimento e fator de condição de Cichla kelberi (Perciformes, Cichlidae) introduzidos em um lago artificial no sudeste Brasileiro

The length-weight relationship and condition factor for Cichla kelberi introduced in an artificial lake in southeastern Brazil were analyzed. By studying separately the male, female and immature individuals, different length-weight patterns were found to happen among them. The same happened when distinct seasonal variations were compared. They are related to feeding alterations and me reproductive periods. The length-weight relationship and condition factor for these fishes vary in accordance with the time of introduction, population size, the characteristics of the ecosystem, sexual maturity, as well as the intra- and interspecific interactions.

Reproduction, food dynamics and exploitation level of Oreochromis niloticus (Perciformes: Cichlidae) from artisanal fisheries in Barra Bonita Reservoir, Brazil

Nile tilapia (Oreochromis niloticus), which is exotic to South America, is the most common species caught in artisanal fisheries at the Barra Bonita Reservoir, Southeastern Brazil. This species is of great socioeconomic importance for the region and keeps active a population of about 500 fishers. In the present study we assess reproduction, food dynamics and level of exploitation of O. niloticus, caught by artisanal fisheries in the Barra Bonita Reservoir. Specimens were collected monthly, from July 2004-June 2005, and a total of 1 715 specimens were analyzed. Each specimen was examined to obtain biological and biometric data: standard length (cm), total weight (g), reproductive data (sex and stage of maturation), and stomach contents (empty, partly full, and full). We also estimated the sex ratio (by macroscopic observation of gonads), reproductive period (by ovarian development and seasonal average of gonadosomatic index in females), and feeding habits (by stomach contents). The possible relationship between abiotic factors and the reproductive period was statistically verified using Spearman's Rank Correlation. The FiSAT (ELEFAN I) package was used to assess growth parameters, mortality rates and to infer exploitation rate from standard length frequencies. The O. niloticus population had a sex ratio of 1.3:1 (M:F). Results indicated that ripe females were captured throughout the year, with a higher frequency during the winter-2004 (with a frequency of 59%, at a mean temperature of 20.5°C), and in spring-2004 (with a frequency of 60.5% at a mean temperature of 21.18°C). The GSI mean values obtained by season were: winter-2004: 1.71; spring-2004: 1.72; summer-2005: 0.80, and autumn-2005: 1.19. The Spearman correlation indicated positive values with respect to pH, dissolved oxygen, electric conductivity, transparency and chlorophyll a, and negative values with respect to temperature, accumulated rainfall and altimetric benchmark. The main food items were phytoplankton and periphytic algae, observed in 99.6% of the analyzed stomachs. The estimated growth and mortality parameters were: L∞=33.60cm, k=0.63/year, longevity= 4.76years, Z=2.81/ year, M=1.20/year and F=1.61/year. The weight-length relationship was Ln Wt=-2.8532+2.8835 Ln Lp. The estimated yield per recruit values were as follows: E=0.570, Emax=0.776, E0.1=0.604 and E0.5=0.349. These results indicate that a well established population of O. niloticus is present at Barra Bonita Reservoir; with an active reproduction throughout the year, more intense during winter and spring, and that O. niloticus is a phytoplanktophagus species. There were no indications that this species is being overfished, we therefore recommend that, due to its exotic condition, no restrictions need to be taken on its fishing activities.

The helminth community of Geophagus proximus (Perciformes: Cichlidae) from a tributary of the Paraná River, Ilha Solteira Reservoir, São Paulo State, Brazil

This study aimed to evaluate the helminth parasites of Geophagus proximus from the São José dos Dourados River, a tributary of Paraná River, Ilha Solteira Reservoir, São Paulo State, Brazil. From May 2006 to May 2007, 116 G. proximus specimens were examined and seven different taxa of helminth were collected and identified: proteocephalidean plerocercoids (Cestoda); metacercariae of Austrodiplostomum compactum, Clinostomum heluans and Clinostomum sp. (Trematoda); and Raphidascaris (Sprentascaris) hypostomi, and larvae of Raphidascaris sp. and Contracaecum sp. (Nematoda). All parasites presented the typical aggregated pattern of distribution, as well as the presence of a high number of larval stages, an absence of influence of the host sex and seasonality upon community parameters, as well as a correlation between species richness and host body weight. Moreover, with the exception of A. compactum metacercariae, all helminths found in this study are reported for the first time in G. proximus. Copyright © Cambridge University Press 2012.

Ciclo reprodutivo e análise ultraestrutural da espermatogênese de Cichla kelberi (TeLeostei: Perciformes: Cichlidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação do potencial genotóxico e mutagênico do Rio Paraíba do Sul, numa área sob influência de uma refinaria de petróleo, utilizando Oreochromis niloticus (Perciformes, cichlidae) como organismo-teste

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Contribuições ao conhecimento de cromossomos supernuméricos em peixes, utilizando como modelo Haplochromis obliquidens (Perciformes, Cichlidae)

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

Estudo da dieta do Lutjanus synagris (Linnaeus, 1758) e Ocyrus chrysurus (Bloch, 1791), teleostei :perciformes: lutjanidae, no banco dos abrolhos, Bahia, Brasil e pesca das principais espécies de lutjanídeos e serranídeos na região

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Caracterização espermáticas na subfamília Cichlinae (Perciformes : Chlidae) e suas implicações filogenéticas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)