12 resultados para Cladocera - Distribuição geográfica

em Aquatic Commons


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Este libro pretende reunir la información disponible sobre la distribución geográfica precisa de los peces continentales del país. Hasta el momento esta información se encontraba dispersa en varios cientos de publicaciones, muchas de ellas díficiles de encontrar por ser antiguas, estar publicadas principalmente en revistas extranjeras que se reciben en unas pocas -o a veces ninguna- biblioteca o estar en publicaciones de difusión restringida. A raíz de lo anterior, esta tarea sólo pudo ser posible gracias a la colaboración de los autores de los trabajos recopilados, y en particular a la ayuda de la cátedra de Ictiología de la Universidad Nacional de La Plata que posee una gran mayoría de la bibliografía utilizada. Es mi intención continuar trabajando en la actualización permanentemente de esta base de datos. Por este motivo, y en la medida en que esta recopilación les resulte de utilidad, les solicito a todos los que trabajan en las distintas facetas, básicas y aplicadas, de la ictiología, que envíen copias de sus trabajos publicados a la dirección: Impresos Fundación Oga Programa Conservación de Peces Continentales Alem 272 - 2900 San Nicolás de los Arroyos Buenos Aires, Argentina Formato eléctronico jliotta@fundacionoga.org.ar (PDF tiene 654 paginas.)

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Fourteen stations were sampled in the Kenyan waters of Lake Victoria in order to assess distribution and abundance of zooplankton. Seven stations were selected in the Nyanza gulf while the rest were in the open waters of the lake. Zooplanktons samples were collected monthly from November 1998 to January 1999, using a 1.5 m long Nansen type plankton net of 243 mu m mesh size and 50 cm diameter. Representative specimens were dissected and identified to species level

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Sensillae of the limbs of Cladocera are described with emphasis on Eurycercus lamellatus.

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In a survey of histological preparations of several hundreds of Moina macrocopa Straus , one specimen was discovered, in the left ovary of which was found a parthenogenetic embryo. The short article includes an illustration of a transverse section of parthenogenetic female of Moina macrocopa.

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The behaviour in the feeding process and the functional morphology of Lathonura rectirostris O.F. Muller - one of the widely distributed species of macrothricids - is studied. The current work is an attempt at morpho-functional analysis of the apparatus of the trunk appendages of Lathonura rectirostris O.F. Muller. This highly specialized species, the method of feeding of which basically comes to the mechanical scraping-off and collection of epiphytic single-celled algae and particles deposited on the surface of aquatic plants.

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The feeding methods of macrothricids was investigated in three species — Ophryoxus gracilis G.O. Sars, Ilyocryptus sordidus (Lievin) and Lathonura rectirostris O.F.Muller. The procuring of food in those species follows two methods: filtration of dispersed particles or scraping off and collecting food from the surface of the substrate. When collecting food by scraping off is the sole method of feeding (as in Lathonura rectirostris), movement along the substrate and feeding are combined so intimately that they appear as parts of one and the same mechanism.

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In species of Cladocera not forming ephippia, the latent eggs have a sheath formed by glands of the reproductive canals. Representatives of the families Daphniidae and Moinidae Goulden, 1968, in connection with the formation of their complex-structured ephippia, lost these glands. It was investigated whether there are such glands in species the latent eggs of which are enclosed in primitive ephippia. For this, with the help of histological methods, 55 females of Acroperus elongatus (Sars) (Chydoridea) and 88 females of Lathonura rectirostris (O. F. Muller), (Macrothricidae) were collected near Leningrad, were studied.

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Identification keys to families of Cladocera and to subfamilies, genera, species and subspecies of Macrothricidae and Moinidae are given. This translation does not include ecological notes or illustrations.

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The determination of relative connections between families and genera of Cladocera, necessary for the construction of their natural systems, must be based on various criteria, among them on the structure of the ephippia. Of particular interest is the study of the process of formation and structure of the ephippium in Macrothricidae, different representatives of which differ significantly among themselves according to this criterion. In this article are presented the results of an investigation of the features of formation of the ephippium in seven species of Macrothricidae and in the moinid Moina weismanni Ishikawa (Moinidae).

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Usually stenobiotic species are used as hydrobiological indicators of the degree of pollution in natural waters. Cladocera are eurybiotic organisms, therefore their role as specific indicators of the water quality is considered to be insignificant. However, considering new methods Cladocera at present are more and more often used as indicators of oligo- and mesosaprobic waters as well as of the presence of considerable amounts of easily degradable organic matter. Work over many years on the biology of Polyphemus pediculus, this striking representative of the order Cladocera, convinced the author of the possibility of using this species not only as an indicator of water purity but also for the estimation of the degree of water pollution as well as of water characteristics such as colour, turbidity, oxgen content and chemical composition. P. pediculus is one of the most common and abundant species of planktonic crustaceans in shallow waters of reservoirs, rivers, lakes, ponds and temporary water bodies.