RESUMO

Fish fauna was studied in five sites of the shallow infralittoral of the Paranaguá Bay during the period from October 1999 to September 2000. At each sampling site, fish were sampled with other trawls, salinity and temperature were measured, water samples were taken from the bottom of the water column for determination of dissolved oxygen, dissolved inorganic nitrogen and phosphate. The spatial and temporal behavior of the environmental variables was analyzed by a Principal Component Analysis; Cluster Analysis was used to gather the sampling sites, and Factorial Correspondence Analysis was applied to the most abundant species. Temperature was themost important variable for the distribution of the months, allowing the division of the study period into hot and cold months. The temporal variation in the fish fauna composition was indicated by cluster analysis, with highest percentages of dissimilarity between the sampling sites during hot months. The variation in dissimilarity between the sites occurred due to differences in the number of individuals and species of the catches. The high frequencies of occurrence of Anisotremus surinamensis, Etropus crossotus, Genidens genidens, Micropogonias furnieri and Sphoeroides greeleyiwere related to high temperatures. The greatest number of fish and species observed in hot months may be related to the life cycle of many species, which reproduce in warmer months, and whose offspring use estuaries as breeding areas.

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RESUMO

Dinoflagellates of the genus Ceratium are chiefly marine but there are rare occurrences in freshwater. In this study we analyze the invasion and progressive establishment of Ceratium furcoides, an exotic species, in the Furnas Reservoir. Samples were taken at 36 points in the reservoir, during the months of March, June, September and December, 2007. Measurements of some physical and chemical variables were simultaneously performed at each site. The occurrence of C. furcoides was registered at 20 sites, with densities varying between 0.57 and 28,564,913.0 ind.m-3. Blooms of this species were recorded in points which were classified as mesotrophic, coinciding with the places receiving high amounts of untreated domestic sewage. C. furcoides density was correlated with temperature, nutrients (nitrate and nitrite) and water electric conductivity. The highest density was recorded in June when temperature was low. The presence of Ceratium furcoides in the reservoir apparently has not yet affected the reservoir water quality or other plankton communities. However, if it becomes fully established it could perhaps become a problem in the reservoir or even to spread out to other reservoirs in Rio Grande basin.

Dinoflagelados do gênero Ceratium são principalmente marinhos, porém existem raras ocorrências em água doce. Neste estudo analisamos a invasão e o estabelecimento progressivo de Ceratium furcoides, uma espécie exótica no reservatório da UHE de Furnas. Foram coletadas amostras em 36 locais em todo o reservatório durante os meses de março, junho, setembro e dezembro de 2007. Variáveis físicas e químicas foram aferidas em cada local. C. furcoides ocorreu em 20 dos 36 pontos de coleta, em densidades que variaram entre 0.57 e 28.564.913 ind.m-3. A maior densidade da espécie foi registrada na região do rio Marimbondo (G14) classificada como mesotrófica e local onde alto volume de esgoto doméstico sem tratamento é lançado diariamente. A densidade de C. furcoides foi correlacionada com os valores de temperatura, nutrientes dissolvidos (nitrato e nitrito) e com a condutividade elétrica. Até o momento do presente estudo, a presença de Ceratium furcoides no reservatório aparentemente não afetou as condições ambientais ou outras comunidades, porém, ao se tornar plenamente estabelecida poderá se transformar em um risco ecológico e até mesmo espalhar-se para outras bacias.

RESUMO

The Blue Peacock Bass (Cichla piquiti), native to the Tocantins-Araguaia river basin of the Amazon system, was introduced into the basin of the Paranaíba River, Paraná River system. Cachoeira Dourada reservoir is one of a series of dams on the Paranaíba River in central Brazil, where this fish has become established. A study of its feeding spectrum, combined with information about its reproductive characteristics and population structure, would enable the current state of this species in the reservoir to be assessed and might provide useful data for the management of other species native to this habitat. This study showed that the peacock bass has no predators or natural competitors in the reservoir and that reproduces continuously, with high reproductive rates, and has a smaller median length at first maturity (L50) than other species of Cichla. Its successful establishment in habitats strongly affected by human activity should cause changes in the whole structure of the local fish communities. Nonetheless, in this reservoir, there appears to be some sharing of the functions of this species with native carnivorous fish, a situation that may be sustained by the presence of a wide variety of foraging fish.

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Os riachos costeiros apresentam grande diversidade de peixes, apesar dos impactos a que são submetidos. O conhecimento da estrutura e da composição da ictiofauna constitui importante esforço para levantamento de parâmetros de avaliação que possam proporcionar atitudes para a conservação destes ambientes. A composição da ictiofauna relacionada a características fisiográficas de riachos costeiros do sul do Brasil constitui-se uma contribuição para a interpretação da dinâmica destes ecossistemas. Foram realizadas coletas de peixes em cinco pontos amostrais do Rio do Pinto, localizado no município de Morretes, Paraná, Brasil. As coletas foram realizadas entre os meses de maio de 2006 a novembro de 2007, utilizando a técnica de pesca elétrica, com um esforço amostral de 50 m/hora em cada localidade. Os animais coletados foram fixados em formaldeído 10 por cento. Cada localidade foi classificada em relação ao tipo de substrato, profundidade, velocidade de correnteza e largura média. Foi possível observar a relação direta entre o tipo de substrato e a composição da ictiofauna. Em regiões onde a granulometria era maior, tais como matacões e seixos, prevaleceram os Siluriformes. Por outro lado, em regiões onde o sedimento apresentava menor granulometria, tais como areia grossa associada a cascalho, ocorreram espécies de Characiformes.

In spite of the impacts that tropical streams are submitted, they still present a great fish diversity. The knowledge of the fish structure and composition is an important attempt in order to stabilish evaluation parameters that can favour conservation of these environments. The icthyofaunal composition related to physiographic features of coastal streams of south Brazil is an important contribution to the interpretation of these ecosystem dynamics. We perform fish collections in five sampling sites in the Pinto River, placed in Morretes municipality in the Paraná State, Brazil. The samples were accomplished between May 2006 and November 2007, using electric fishing along 50 m/hour in each site. The collected animals were fixed in formaline 10 percent. Each site (point) was classified in relation to the bottom substratum, depth, width average, and current speed. Direct relationship between substratum type and fish compostition was observed. Siluriformes were predominant in places with coarseness granulometry, such as boulders, cobbles and pebbles. On the other hand, Characiformes were predominant in places with smaller granulometry, such as coarse sand and gravel.

RESUMO

Fipronil is a phenylpyrazole pesticide widely used to protect sugar-cane crops from insect pests. After reaching the environment, this insecticide may have several fates. This research aimed to propose a kinetic model to describe the fate of commercial fipronil Regent 800WG in the sediment-water interface of the Oleo Lagoon in the Mogi-Guaçu river floodplain, situated within the Jataí Ecological Station, by means of a microcosm scale experiment. Results showed that a small fraction of the pesticide is quickly dragged to the sediment while most of it remains in the water column. Biodegradation proves to be an important fipronil degradation route, especially when microorganisms capable of using fipronil as sole carbon source increase their population, as a function of exposure time. Biodegradation rates were higher in the sediment than in the water column.

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The purpose of this research is the evaluation of the growth of Loricariichthys anus from the Emboaba Lagoon, Rio Grande do Sul, Brazil. The mathematical model used was the von Bertalnffy's one (1938). The growth curves had their parameters estimated through the method of annual rings observed in otoliths and vertebra. This study showed the positive allometric growth and sexual dimorphism in relation to the growth curves. The females are significantly larger than the males, however the males reach their asymptotic length more rapidly.

O objetivo do trabalho é estudar o crescimento de Loricariichthys anus na lagoa Emboaba, Rio Grande do Sul, Brasil. O modelo empregado foi o de von Bertalanffy (1938), sendo suas constantes estimadas pelo método dos anéis etários em otólitos e vértebras. Ficou evidenciado o crescimento alométrico positivo dos indivíduos e o dimorfismo sexual quanto às curvas de crescimento. As fêmeas são significativamente maiores que os machos, que, por sua vez, apresentam um crescimento mais acelerado.

RESUMO

The purpose of this research is the evaluation of the growth of Loricariichthys anus from the Emboaba Lagoon, Rio Grande do Sul, Brazil. The mathematical model used was the von Bertalnffy's one (1938). The growth curves had their parameters estimated through the method of annual rings observed in otoliths and vertebra. This study showed the positive allometric growth and sexual dimorphism in relation to the growth curves. The females are significantly larger than the males, however the males reach their asymptotic length more rapidly.

O objetivo do trabalho é estudar o crescimento de Loricariichthys anus na lagoa Emboaba, Rio Grande do Sul, Brasil. O modelo empregado foi o de von Bertalanffy (1938), sendo suas constantes estimadas pelo método dos anéis etários em otólitos e vértebras. Ficou evidenciado o crescimento alométrico positivo dos indivíduos e o dimorfismo sexual quanto às curvas de crescimento. As fêmeas são significativamente maiores que os machos, que, por sua vez, apresentam um crescimento mais acelerado.