The structure of Cichla kelberi population was characterized regarding the sex ratio, total length composition and some reproductive characteristics. The specimens were collected in two periods, from November 2002 to November 2003 and from December 2004 to May 2006. The sex ratio was significantly different than 1:1. The total length varied from 3.4 to 40.1 cm, with individuals in the shortest length classes occurring throughout the year, but with greater incidence in the warmer periods. Females and males reached similar lengths and there was no difference between the sexes regarding the length-weight relationship.The estimated values of condition factor were near the central value of 1.0 and decreased during the cooler months, coinciding with periods of lower reproductive activity. Individuals with mature or semi-spent gonads occurred from November to April, indicating that Cichla kelberi reproduces for a long period of time. The spawning is partitioned, with an average absolute fecundity of 6072 oocytes (from 5220 to 6908 oocytes). The high relative condition factor values, long reproductive period, large output of fingerlings and high fecundity are biological conditions that indicate the species is well adapted in this reservoir.A população de Cichla kelberi foi caracterizada quanto à proporção sexual, composição em comprimento total e algumas características reprodutivas. As coletas foram realizadas em dois períodos, de novembro de 2002 a novembro de 2003 e de dezembro de 2004 a maio de 2006. A proporção sexual foi significativamente diferente de 1:1. Os comprimentos totais variaram de 3,4 a 40,1 cm sendo que a ocorrência de indivíduos nas classes de menor comprimento se deu ao longo de todo o ano, com maior incidência nos períodos mais quentes. Fêmeas e machos atingem comprimentos similares e não houve diferença entre os sexos quanto à relação peso -comprimento. Os valores do fator de condição estimados foram próximos ao valor centralizador 1.0 e apresentaram quedas nos meses mais frios, coincidindo com períodos de menor atividade reprodutiva. Indivíduos com gônadas Maduras ou Semi Esgotadas ocorreram de setembro a abril, indicando que Cichla kelberi reproduz-se por um longo período. A desova é do tipo parcelada e apresenta, em média, uma fecundidade absoluta de 6072 ovócitos (de 5220 a 6908 ovócitos). Os altos valores de fator de condição relativo, longo período reprodutivo, grande produção de larvas e fecundidade alta são condições biológicas que indicam boa adaptação da espécie neste reservatório.

The introduction of species has become an important problem for biodiversity and natural ecosystem conservation. The lake system of the middle Rio Doce (MG, Brazil) comprises c. 200 lakes at various conservation states, of which 50 are located within the Rio Doce State Park (PERD). Previous studies had verified several of these lakes suffered non-native fishes introductions and the presence of these species needs for the implementation of actions aiming at not only their control but also the preservation of the native species. This study discusses the effects of non-native fish species in the largest conservation unit of Atlantic Forest in Minas Gerais, southeast of Brazil, using data from 1983 to 2010 distributed as follow: data prior to 2006 were obtained from previous studies, and data from September 2006 to July 2010 were obtained in Lake Carioca at four sampling stations using gillnets, seine nets and sieve. A total of 17 fish species was collected (2006)(2007)(2008)(2009)(2010) of which five were introduced species. Among the small to medium size native species (30 to 2000 mm standard length) seven had disappeared, two are new records and one was recaptured. The non-native species Cichla kelberi (peacock bass) and Pygocentrus nattereri (red piranha) are within the most abundant captured species. Integrated with other actions, such as those preventing new introductions, a selective fishing schedule is proposed as an alternative approach to improve the conservation management actions and the local and regional biodiversity maintenance.Keywords: fish fauna, biological invasion, Rio Doce basin, conservation management, local extinction. Palavras-chave: ictiofauna, invasão biológica, bacia do Rio Doce, manejo conservacionista, extinção local. Perda de biodiversidade em uma unidade de conservação da Mata Atlântica brasileira: efeitos da introdução de espécies não nativas de peixes

During studies carried out with a small characid (Astyanax scabripinnis), from the Brazilian streams located in

The trophic ecology of ichthyofauna in a stream can be related to the presence or absence of riparian and aquatic vegetation, and mainly resource availability. Therefore, the aim of this study was to analyse the seasonal and ontogenetic variations for the trophic ecology of Hemigrammus marginatus in the Beija-Flor stream located at the Jataí Ecological Station in the municipality of Luiz Antônio-SP, Brazil. In order to attain this objective, the data collections were carried out on a monthly basis from August, 2011 to July, 2012. Fish were collected using a trawl net and bait traps from three collection stations distributed along the Beija-Flor stream. The quality of the water was evaluated by the chemical variables: ammonia, nitrate, total nitrogen, total phosphorus, and physical temperature, dissolved oxygen, pH, turbidity and conductivity, obtained by using a Yellow Springs sonde. The collected specimens were fixed in 10% formalin in the field and were subjected to biometric measurements in the laboratory. The stomachs were weighed and transferred to 70% alcohol and the stomach contents were analysed using a stereomicroscope at the lowest possible taxonomic level. The species was considered insectivorous and the autochthonous food items were the most important during the dry season, mainly from the orders Ephemeroptera and Trichoptera, while allochthonous items from the order Hymenoptera were more important in the wet season. The young individuals' diet was based on the consumption of zooplankton, and insofar as the fish develops, there was a decrease in this item in the diet showing that the species has ontogenetic shifts in its diet. The conservation state of the Beija-Flor stream, as well as the flexibility of using food and food resources provided by aquatic macrophytes and riparian vegetation are key factors for the high abundance of the H. marginatus species.Keywords: stream fish, diet, ontogenetic variations, riparian vegetation, upper Paraná basin, seasonality. Ecologia trófica do Hemigrammus marginatus Ellis, 1911 (Characiformes, Characidae) em um riacho tropical conservado ResumoA ecologia trófica da ictiofauna em um riacho pode estar relacionada à presença ou ausência de mata ciliar e vegetação aquática, e principalmente pela disponibilidade de recursos no ambiente. Assim, o objetivo deste estudo foi analisar as variações sazonais e ontogenéticas na ecologia trófica de Hemigrammus marginatus no córrego Beija-Flor, localizado na Estação Ecológica de Jataí, localizada no município de Luiz Antônio-SP, Brasil. Para atender esse objetivo as coletas de dados foram realizadas mensalmente no período de agosto de 2011 a julho de 2012. Os peixes foram coletados utilizando rede de arrasto e armadilhas iscadas, em três estações de coleta distribuídas ao longo do córrego Beija-Flor. A qualidade da água foi avaliada pelas variáveis químicas amônia, nitrato, nitrogênio total, fósforo total, e físicas temperatura, oxigênio dissolvido, pH, turbidez e condutividade, obtidas com auxilio de uma sonda Yellow Sp...