Browsing by Author "Moreno, Carlos"
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Item Distribución y segregación espacial de las poblaciones de peces en bahía South (Isla Doumer, Antártica)(1977) Moreno, Carlos; Zamorano, Juan; Duarte, WilliamThe vertical and local distribution of coastal benthonic·fish populations was studied at South Bay, Doumer Island, Palmer Archipelago, in relation to the habitats found in the marine bottom substrate.• The populations were separated according to their habitat preference utilizing three different methods: a) analysis of vertical distribution, b) analysis of relative density and e) analysis of geographic microdistribution, a measure of similarity in appearance of 43 sampling stations utilized in the summer's of 1972, 1973, 1976 and 1977. The three methods gave similar results, which permitted the grouping of similar species; one group that congregates the fishes of the algal belt and the other congregates the fishes of the sponge community. When we compared our results with the literature, we concluded that the same species occupy similar habitats in very different places around Antarctica. The probable ecological isolation of 4 congeneric species is discussed according to microhabitat within the algal belt from the observations taken while scuba diving.Item Hábitos alimentarios del Cormorán Antártico, Phalacrocorax atriceps bransfieldensis (Murphy) en Isla Green, Antártica(1976) Schlatter, Roberto; Moreno, CarlosThe diet of the Blue- eyed Shag, (Phalacrocorax atriceps bransfieldensis) was studied based upon remains and pelletes eyected by that species colony at Green Island, Antarctic Peninsula. This cormorant consumes preferably juvenile Notothenid fishes and Cephalopoda, minor food items were pelagic and bentho-litoral Crustaceans. The advantage and disadvantage of pellets for food habit studies, the presence of stones in those castings and the role plus trophic relations of the Blue-eyed Shag in the antarctic marine ecosystem are discussed.Item "Nichos alimentarios y competencia por alimento entre Notothenia coriiceps neglecta Nybelin y Notothenia rossii marmorata Fischer en Shetland del Sur. Antártica(1975) Moreno, Carlos; Bahamonde, NibaldoThe gastric content of Notothenia coriiceps neglecta NYBELIN and Notothenia rossii marmorata FISHER collected in two localities around the South Shetlands Islands, Antarctica is studied. To quantify those contents the numerical and frequency methods are used. Sorensen's index of faunistic affinites is applied in order to establish feeding differences among both species and to find out numerically, food competition at localities of capture. Trophic diversity using Margalef's formula (1957) are calculated. The results obtained suggest a relationship between competition for food and trophic diversity. The Chile bay could be characterized by a high competition and low trophic diversity while in Fildes bay a low competition for food and a high trophic diversity has been detected.Item The Trophic Niche of Pleuragramma antarcticum in the Bransfield Strait, Antarctica: Quantitative Comparison with other Areas of the Southern Ocean(1986) Moreno, Carlos; Rueda, Teresa; Asencio, GladysThe stomach contents of Pleuragramma antarcticum Boulenger was studied in specimens collected in 14 of 27 IKMT stations, during the SIBEX-II expedition to the Bransfield Strait, Antarctica. The aims of the research was to know the trophic niche developed for this species during the ecological radiation of the Nototheniids. With the same objective we reviewed the previously published data of gut contents, and were compared using a quantitative approach in order to find the common elements in the diet of the silver-side in a wide variety of ecological conditions at the Antarctic pelagic ecosystem. We found in our study, that in the Bransfield area the predominant food item in the class 1 + was eggs of crustraceans and in the classes 2 + and 5 + was the copepod Metridia gerlachei. This species of copepod has been present in all the previously reported papers. In some opportunities together with krill, heteropods or other copepods, but undoubtedly it is the food item more constant in the diet of Pleuragramma antarcticum. With this information at hand we propose that the Antarctic silver-side has exploited an holopelagic niche using the more abundant and predictable resource namely copepods rather than krill as it has been proposed by other authors.