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Artigos Acadêmicos

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Título: Temporal variation in fish composition and abundance in a perennial tributary of the rio Paraguaçu, a little-known drainage in the Brazilian semi-arid region

Autores: SANTOS, Alexandre Clistenes de A.; CARAMASCHI, Érica P.

Resumo: O rio Santo Antônio é um rio perene e de planície do Semi-árido brasileiro, sendo o principal tributário do alto curso do rio Paraguaçu, importante componente da bacia de drenagem da Chapada Diamantina. Neste trabalho foi avaliada a variação temporal na composição e abundância da ictiofauna em um trecho de seu médio curso. As amostras foram realizadas mensalmente entre agosto de 1998 e julho de 1999, utilizando-se apetrechos e artes de pesca padronizadas. Juntamente com a coleta dos peixes foram tomados os parâmetros ambientais de temperatura da água e do ar, transparência da água, profundidade máxima e média, largura e área do canal e velocidade da corrente. Análises estatísticas univariadas e multivariadas foram utilizadas visando detectar diferenças temporais significativas na abundância das espécies e nos parâmetros ambientais. A temperatura, a transparência e a profundidade do canal mostraram tendências opostas entre os períodos seco e chuvoso. A riqueza da comunidade de peixes (32) e a composição não variaram entre os dois períodos, entretanto espécies de maior porte capturadas por redes-de-espera foram mais abundantes no período chuvoso. Nós concluímos que as poucas mudanças nas condições hidrológicas do rio entre os dois períodos levaram a uma fraca resposta da comunidade de peixes local. Monitoramentos de longo prazo serão necessários pra acessar a real persistência da estrutura da comunidade de peixes neste rio perene do Semi-árido brasileiro.

Palavras-chave: Chapada Diamantina, Ictiofauna , Riqueza , Sazonalidade.

Title: Temporal variation in fish composition and abundance in a perennial tributary of the rio Paraguaçu, a little-known drainage in the Brazilian semi-arid region

Authors: SANTOS, Alexandre Clistenes de A.; CARAMASCHI, Érica P.

Abstract: The rio Santo Antônio is a perennial lowland stream in the Brazilian semi-arid region, and is the main tributary of the upper rio Paraguaçu, an important drainage of the Chapada Diamantina. The temporal variation of the fish composition and abundance in a stretch of the middle course of the river was evaluated. Sampling was carried out monthly between August 1998 and July 1999, using standardized gear and techniques. Data on water and air temperature, water transparency, maximum and mean depth, width and area of the channel, and flow were recorded on each fish sampling occasion. Univariate and multivariate statistical analyses were employed in order to detect significant temporal differences in environmental parameters and fish abundance. Temperature, transparency and channel depth drove opposite tendencies between the dry and rainy months. The fish community richness (32) and composition did not change between these periods, but large fish caught with gillnets were more abundant in the rainy months. We conclude that the undramatic disturbance in the hydrological stream conditions between the dry and rainy periods led to weak responses of the fish assemblage. Long-term monitoring would be necessary, however, to assess the real persistence of the fish community structure in this perennial stream.

Keywords: Chapada Diamantina, Ichthyofauna, Richness, Seasonality.

     
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Title: Effects of substratum type on fish assemblages in shallow areas of a tropical estuary

Authors: REIS-FILHO, José Amorim; SANTOS, Alexandre Clistenes de Alcântara

Abstract: While there is already a comprehensive understanding of the effects of environ-mental variables, such as dissolved oxygen, temperature and salinity, on the structure, biomass and metabolism of aquatic biota in estuarine habitats, the effect of sedimentation, a harmful underlying factor, remains unclear. The aim of this study was to assess the differences in fish assemblages along the freshwa-ter to salt water gradient of a large tropical estuary, and to evaluate the effects on them of habitat disturbance associated with shallow water sedimentation in the intertidal areas. Fish and environmental variables were recorded in the upper, middle and lower salinity zones of the estuary at ebb tide in both the dry and wet seasons. Sediment samples associated with different levels of habi-tat disturbance were analysed using granulometry, and their organic content and dissolved oxygen levels were quantified. Water temperature, salinity, pH and dissolved oxygen levels were also measured. Habitat disturbance was found to be correlated with the density, biomass and richness of fish assemblages. A total of 77 species were recorded, forming two distinct fish assemblages, with the Eleotridae family dominating in the upper zone, and Gerreidae, Gobiidae and Tetraodontidae the most common in the middle and lower estuary. Changes in the structure of fish assemblages, including reductions in density, biomass and richness, were associated with disturbance to natural features, where muddy sediment was replaced by sandy sediment and the quantity of organic matter fell. Atherinella brasiliensis was the species which showed a pref-erence for the disturbed areas in the middle and lower zones, while Dormitator maculatus showed a preference for them in the upper estuary. They may be taken as indicators of habitat disturbance due to shallow sedimentation.

Keywords: Bioindicator species; fish fauna; Paraguaçu river; sedimentation; tropical estuary.

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Título: Abelhas (Hymenoptera, Apoidea)

Autores: AGUIAR, Cândida Maria Lima; GIMENES, Miriam; REBOUÇAS, Patrícia Luiza de Oliveira

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Título: Flora da Bahia: Cabombaceae

Autores: LIMA, Carla Teixeira de; GIULIETTI, Ana Maria; SANTOS, Francisco de Assis Ribeiro

Resumo: É apresentado o levantamento florístico de Cabombaceae do estado da Bahia, Brasil. Foram reconhecidas quatro espécies do gênero Cabomba: C. aquatica, C. caroliniana, C. furcata e C. haynesii. O tratamento inclui descrição dos táxons, além de chave de identificação, ilustrações e comentários para as espécies.

Palavras-chave adicionais: Brasil, Cabomba, florística, plantas aquáticas, taxonomia.

Title: Flora of Bahia: Cabombaceae

Authors: LIMA, Carla Teixeira de; GIULIETTI, Ana Maria; SANTOS, Francisco de Assis Ribeiro

Abstract: The floristic survey of the Cabombaceae from Bahia State, Brazil, is
presented. Four species of the genus Cabomba were recognized: C. aquatica, C. caroliniana, C. furcata, and C. haynesii.
The treatment includes descriptions of taxa, as well as key for identification, illustrations, and commentaries for each
species.

Keywords: aquatic plants, Brazil, Cabomba, floristics, taxonomy.

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Título: Scarabaeidae (Coleoptera) na Caatinga baiana: Distribuição e Planejamento de pesquisas

Autor: CAMPOS, Elkiaer Moraes

Resumo: A Caatinga é o principal bioma da Região Nordeste, ocupando uma área de cerca de 735.000 km², e que sofre com processo de antropização desde o principio da colonização e que continua até os dias atuais, o que vem resultando num processo acelerado de desertificação e de perda da biodiversidade nas últimas décadas. Partindo desse cenário, o objetivo deste trabalho é sistematizar a informações sobre Scarabaeidae na caatinga baiana buscando um planejamento de pesquisa para o grupo. Para isso são utilizadas informações de coleções zoológicas e amostragens em diversas áreas de caatinga do estado, analisadas quanto à riqueza e composição e, através da utilização de técnicas de modelagem de distribuição de espécies para análises de similaridades ambiental, propomos um planejamento de pesquisa para o grupo. Foram reconhecidas 81 espécies advindas de 27 localidades, sendo cerca de 60% delas de ocorrência única; encontrou-se também relação entre os Scarabaeidae e as fisionomias de caatinga. As análises de similaridade ambiental mostraram uma tendência de preferência dos Scarabaeidae pela parte leste em direção ao sul e região oeste-noroeste. Por fim gerou-se um mapa inicial indicativo de áreas mais indicadas para pesquisa em Scarabaeidae na caatinga baiana.

Palavras-chave: Scarabaeidae, riqueza, análise ambiental, planejamento em pesquisa.

Title: Scarabaeidae (Coleoptera) na Caatinga baiana: Distribuição e Planejamento de pesquisas

Author: CAMPOS, Elkiaer Moraes

Abstract: The Caatinga is the main biome in the Brazilian Northeast region, occupying an area of about 735,000 km², and suffering with the process of human disturbance from the beginning of its colonization to-day, which in recent decades has resulted in an accelerated process of desertification and loss of biodiversity. Based on this scenario, the objective of this work is to systematize the information on Scarabaeidae in the caatinga of Bahia State looking for a research strategy for the group. In order to reach this goal we used entomological collections information altogether with zoological surveys in various areas of caatinga in the state, and analyzed for Scarabaeidae composition and richness; through the use of species distribution modeling techniques for analysis of environmental similarities we propose a research design for the group. We recognized 81 species that come from 27 locations, with approximately 60% of them in unique occurrences; we also found relationships between Scarabaeidae species and the physiognomic types of caatinga. The similarity analysis showed a trend of environmental preference Scarabaeidae for the eastern region toward the south and also west-northwest region. Finally we generated a map indicating high priority areas for future research on Scarabaeidae in the caatinga of Bahia.

Keywords: Scarabaeidae, richness, environmental analysis, research design.


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