Resumo -O presente estudo descreve a estrutura de tamanho e maturidade sexual das espécies de peixes que vivem associadas às raízes de macrófitas aquáticas durante o período de cheia. Foi o objetivo do trabalho demonstrar que este habitat funciona como um berçário e que a maior parte da sua fauna é composta por indivíduos jovens. Foram coletados 3910 indivíduos de 91 espécies de peixes, em quatro tipos de macrófitas aquáticas (Paspalum repens, Echynochloa polystachya, Eichhornia spp. e "mistura de capins em decomposição") em três lagos de várzea da Amazônia Central (Camaleão, Rei e Janauacá). A ictiofauna foi composta predominantemente por indivíduos menores que 7 cm. Indivíduos jovens formaram a maioria da assembléia (87%). Quarenta e uma espécies são explotadas pela frota pesqueira da região. Conclui-se que este habitat é um berçário importante e que deve ser conservado para manter o potencial dos recursos pesqueiros da Amazônia Central. Palavras-chave:Peixes, macrófitas aquáticas, berçário, maturidade sexual, Amazônia. The Aquatic Macrophytes as Nursery Grounds of the Amazon's Fish Fauna.Abstract: The present research describes the size structure and maturity of the fish that lives associated to roots of aquatic macrophytes during the high water period. The main objective was to test the hypothesis that this habitat functions as nursery ground to the fish fauna of the macrophytes (Paspalum repens, Echynocloa polystachya, Eichhornia spp. and mixed decomposing grasses) at three floodplain lakes (Camaleão, Rei and Janauacá). Most fish (90%) were shorher than 7 cm. The fish fauna was composed by 87% young individuals, which 41 species were commercialy exploited. These results indicate that this habitat is an important nursery ground and its conservation will safeguard fisheries resources.

The effects of a disturbance by sandbank opening on the sh fauna community were evaluated through a long-term study in the Imboassica coastal lagoon, Rio de Janeiro State, Brazil. The sh and salinity samples were conducted between 1993 and 2004, with the goal of characterizing the structure and effects of four sandbank openings on this community, such as resilience and resistance measurements. During three sandbank openings, between the years of 1993 and 1996, the resilience time of the sh community could not be identied due to the short time period between openings, their magnitude and the discontinuity of the sh sampling. Monitoring studies previously conducted between 1993 and 2004, indicated that factors structuring the sh fauna of Imboassica lagoon are due to salinity !uctuations, in!uenced by the sandbank openings to which this environment is subjected. These events were indicated by the recolonization of primary freshwater species, oligohaline salinity values, and small variations in the composition and abundance on the sh community. Due to the magnitude and frequency of the disturbance, the ichthyic populations available that enter the lagoon from the adjacent ocean plus the resistance of this environment to salinity variations, determined the resilience and resistance of the sh fauna in the Imboassica lagoon. Thus, the resilience of the sh fauna in this lagoon was indicated in groupings of: a) Spearman probability values lower than 0.05 between the pairs of communities pre and post-disturbance; b) presence of freshwater species that indicate resilience; c) salinity values varying between 0 and 5; and d) small alterations in the abundance of sh populations.

Regiões de várzea apresentam alta produtividade biológica e são habitadas por populações que praticam atividades agropesqueiras, baseadas no uso múltiplo dos recursos. A economicidade do sistema conduz os ribeirinhos à apropriação de territórios e a dependência conjunta dos recursos ao estabelecimento de acordos internos, definindo-se critérios de acesso e intensidades de extração. Este estudo, por meio de 244 entrevistas com pescadores e reuniões em 16 comunidades do baixo Solimões, identificou fatores que influenciam na magnitude e finalidade das pescarias, especialmente em pesqueiros de uso coletivo, descrevendo mecanismos de apropriação e conflitos. O trecho abriga dois sistemas de lagos de terra firme e um de lagos de várzea. Para pescarias de subsistência e comercial, foram estimadas área, extensão e frequência de uso por período do ano (seca/cheia). Cada comunidade explorou os ambientes de pesca de acordo com a proximidade e/ou acessibilidade, revelando uso dentro das delimitações territoriais, havendo sobreposição naqueles explorados para subsistência e comércio. Existem conflitos por pesca comercial, esportiva, com pescadores externos à comunidade e com fazendeiros. Não existem proibições ou controle de acesso aos igapós, mas regras informais. Para o manejo integrado na área de estudo, são propostos três cenários de atuação, considerando a diversidade de ambientes e os interesses dos grupos envolvidos.

This study evaluates the total length of tambaqui (Colossoma macropomum ) captured in the middle Solimões river and traded during seven years (1993, 1997 and 2000 to 2005) in the Tefé market, Amazon, Brazil. The Mamirauá Institute of Sustainable Development obtained measurements of the total lengths from 42207 individuals. The length average was 45.23 ± 6.29 cm (minim um of 13 cm and maximum of 105.5 cm ) and the mode was 45 cm . From the total tambaquis, 92.86% were smaller than 55 cm and 7.14% measured 58.24 ± 5.41 cm on average. Medium and standard deviation of the lengths recorded in all years showed sizes below the established by the environmental federal agency. The Kruskal Wallis test showed that there is no significant difference between the abundances and medium sizes of the captures during all months of the year. The historical data of the tambaqui fisheries for the middle Solimões region indicate that individuals of this species have been constantly captured at sizes below the minim um length of reproduction. Nine recommendations for tambaquis fisheries management in the region related to more efficient mechanisms of inspection, auto-ecology studies of the species, environmental protection, reduction of fishery pressure, diffusion and educational cam paigns that aim to correct exploitation of this resource are presented in this manuscript.

Several fish species from Central America and other regions have been introduced into Brazil. In this study, we evaluated the bioecological aspects of a non‐native cichlid of the genus Amatitlania (convict cichlid) and its possible establishment in high‐altitude forest enclaves of semi‐arid Northeastern Brazil. Specimens of Amatitlania nigrofasciata (Günther, 1867) were captured in a local stream displaying abiotic conditions like those of its natural range of distribution. The individuals collected were predominantly adult, insectivorous and displayed normal length–weight relationships, although we observed some phenotypical plasticity (variation in body depth, and a morphologically abnormal dorsal fin in three cases). Our results indicate that A. nigrofasciata has successfully colonized an Atlantic forest enclave in the Brazilian semi‐arid region, making it necessary to adopt measures to prevent the species from spreading to other water bodies in the surroundings.