10 resultados para Known Unknowns

em Aquatic Commons


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Bacterioplankton [pdf] Phytoplankton [pdf] Zooplankton [pdf] Non-exploited fish and invertebrates [pdf] Commercially-important fish and invertebrates [pdf] Marine birds [pdf] Mammals [pdf] Supplemental table of Unknowns [html] (Document pdf contains 48 pages)

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Special Publication 2 On-line version On-line version includes links to the following files (these files are not included into publication): Bacterioplankton [pdf] Phytoplankton [pdf] Zooplankton [pdf] Non-exploited fish and invertebrates [pdf] Commercially-important fish and invertebrates [pdf] Marine birds [pdf] Mammals [pdf] Supplemental table of Unknowns [html]

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An account of Pittier's travels around Panama. Written as a travel guide, Pittier describes the flora and fauna of the different regions as well as the topography, people and geology of the area.

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This partial translation of a larger paper provides taxonomic descriptions of 5 fungal zoospores species: Olpidium vampyrellae, 0. pseudosporearum, 0. leptophrydis, Rhizophidium leptophrydis and Chytridium lateoperculatum.

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A method is presented through which the total mortality undergone by several fish stocks of the same species can be compared when growth parameters are poorly known or unknown. Whereas the estimate of Z obtained via the length-converted catch curve is highly sensitive to the input parameters K and L sub( infinity ), the ratio of Z estimates obtained for different stocks with the same combination of parameters is almost independent of these inputs, at least when the fit of the linear regression is good. The method is tested on simulated data and an application is presented using real data from the Lesser Antilles. It provides the possibility of qualitatively comparing several stocks in situations of scarce biological knowledge.

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Among the fish species of the family Nemipteridae, the two little known species, namely, Nemipterus mesoprion (Bleeker) and Nemipterus delagoae (Smith) are recorded from the Cochin waters. Nemipterus mesoprion is a new distributional record from the west coast of India. N. delagoae is described with adequate numbers of specimen for the first time from Indian waters. Moreover, the results of the present study show that the colour of the viscera, the number of pyloric caeca and the gill rakers can also be used for the diagnosis of the species of the genus Nemipterus. The affinity of the above species with other related species of the genus Nemipterus and their geographical distribution are presented.

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Siganus lineatus (Cuv. and Val) is reported from the coast of peninsular India for the first time and a detailed description of it is given based on morphology and meristic characters. It differs from the other allied species of the genus Siganus Forskal in having an oval body without spots and having fifteen parallel longitudinal golden yellow bands, relatively larger last dorsal spine, maxillary position far below the level of the orbit and cheek with distinct rows of scales. S. javus (Linnaeus) and S. canaliculatus (Park) were also obtained from the Vembanad Lake. Short notes on the habitat, occurrence, abundance, seasonal and geographic distribution in relation to fluctuating hydrological conditions of the Vembanad Lake are incorporated together with a key for their identification.

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This article is a short discussion of the requirements for live food production in aquaculture and a brief presentation of the processes involved.

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Fish introductions have been made from small fish ponds to the largest lakes in Africa. The primary intent of these introductions has been to sustain or increase fish production, although some introductions have been made to develop sport fisheries and to control unwanted organisms. Some of these introductions have fulfilled their objective in the short term, but several of these "successful" introductions have created uncertainties about their long term sustainability. Lates niloticus, Oreochromis niloticus, O. leucostictus, Tilapia melanopleura and T. zilli were introduced into lakes Victoria and Kyoga in 1950s and early 1960s. By the 1980s O. niloticus and O. niloticus dominated the fisheries of these lakes, virtually eliminating a number of endemic fish species. The loss of genetic diversity of the fish in the worlds second largest lake has also been accompanied by a loss of trophic diversity. The transformation of the fish community has, in Lake Victoria coincided with a profound eutrophication (algal blooms, fish kills, hypolimnetic anoxia) which might be related to alterations of the lake's food-web structure. In contrast, the introduction of a planktivore, Limnothrissa miodon into Lake Kivu and the Kariba reservoir has established highly successful fisheries with little documented effect on the pre-existing fish community or trophic ecology of the lakes. The highly endemised species-rich African Great lakes may be particularly sensitive to species introductions and require special consideration and caution when introductions are contemplated because species extinctions, introgressive hybridization and ecosystem alterations may occur following fish introductions.