734 resultados para Meretrix meretrix Linnaeus


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Tesis (Maestría en Ciencias con Especialidad en Química de Productos Naturales) UANL

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Tesis (Maestría en Ciencias con Especialidad en Entomología Médica) U.A.N.L.

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Tesis (Maestría en Ciencias con Especialidad en Entomología Médica) U.A.N.L.

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La malnutrition est identifiée comme l’un des facteurs potentiellement responsables des mortalités élevées de colonies d’abeilles des dernières années au Québec. Pour contrer cela, les apiculteurs donnent des suppléments de pollen à leurs colonies, mais les impacts d’une telle pratique à diverses périodes sont méconnus. Les effets de la disponibilité du pollen sur le développement de colonies d’abeilles ont été mesurés pendant 3 différentes périodes : au printemps, durant la pollinisation de la canneberge et à la fin de l’été. À chacune des périodes correspondait une expérience distincte utilisant 40 colonies. Pour chaque expérience, des conditions d’abondance de supplément de pollen et de restriction de pollen naturel étaient créées chez les colonies pendant un mois selon un plan d’expérience factorielle 2x2. L’élevage du couvain et la récolte de miel ont été mesurés jusqu’à la fin de l’été (début de l’été suivant pour l’expérience de fin d’été). Au printemps, les colonies restreintes en pollen naturel ont élevé 18% moins de couvain (p<0.05) pendant la période de restriction et 11% de moins à la fin de l’été alors que l’utilisation du supplément n’a eu aucun effet (p>0.05). Les colonies supplémentées durant la pollinisation des canneberges ont élevé moins de couvain (p<0.05) à la fin de l’été. Pour l’expérience de fin d’été, les colonies supplémentées ont eut une meilleure reprise printanière (p<0.05) de l’élevage du couvain (60% de plus) alors qu’une restriction en pollen naturel avait un effet négatif (p>0.05). Les récoltes de miel ont été augmentées (p<0.05) de 1,3 kg pendant la pollinisation de la canneberge alors qu’elles ont été diminuées (p<0.05)par une restriction en pollen naturel de 4,2 kg à la fin de l’été et de 15 kg au printemps.

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Department of Marine Biology, Microbiology and Biochemistry, Cochin University of Science and Technology

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The thesis deals with different aspects connected with the distribution and toxicity of PHC in crude oils in the aquatic environment and marine molluscs. Information has been gathered and presented on the present status of research in the field based on a thorough review of recent literature. It is seen from the literature that the resident time of PHC becomes lesser and lesser when crude oil is discharged in large quantities into the coastal waters where excess oxygenation light penetration, temperature availability and strong tidal currents persist. This results in the reduction of the onslaught of oil pollution. This probably shows that taxic insult of crude oil in tropical shores will be relatively lesser than that occurring in temperate and boreal waters. However, there is no record of major episodal oil pollution comparable in quantum and extent to that of Torrey Canyon or Amoco Cadiz which prevents a more reliable analysis on the issue. Considerable controversy exists on the method of estimation of PHC in seawater. However, Ultra-violet fluorescence spectroscopy has been widely recommended as an analytical tool for the determination of total hydrocarbons. Similarly representation of values as chrysene equivalents has been recognised as the most reliable method of Quantum representation.

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This thesis entitled Systematics,life history traits ,abundance and stock assessment of cobia rachycentron canadum (linnaeus ,1766) occurring in indian waters with special reference to the northwest coast of india.Cobia, Rachycentron canadum is a fast growing pelagic fish belonging to the monotypic family Rachycentridae. They show worldwide distribution in tropical and sub tropical waters. Cobia is exploited commercially in various countries like Taiwan, Pakistan, India, United State of America, Australia, Gulf of Mexico and the Caribbean. Recreational fishery of Cobia exists in different parts of the world. In India Cobia is caught as bycatch of trawlers, gillnet and hook and line fishery.This study also focuses on to bring out the distribution pattern and also to assess the biomass and estimate sustainable yield of Cobia inhabiting in Indian EEZ. In addition to above, present study standardised live collection methods and also reviewed culture prospects.Results of osteological study and morphological studies indicate its close resemblance to Remora and support the view that Cobia was evolved from Dolphin fishes and remoras followed it. Study also confirmed that Cobia does not have any relative or similar species and is a monotypic species belonging to the family Rachycentridae. Re description of the species was done based on the characters identified. In this study, feeding intensity was also assessed following methods like Gastrosomatic index, Mean index of feeding intensity and Index of fullness. Sex wise, month wise and length group wise fluctuations in the feeding intensity also were studied. Cobia actively fed during post monsoon period. In general, adult fed actively than the juveniles. Trophic level value estimated (4.36) indicates that Cobia occupy top level position in the food chain.

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The thesis deals with the results of an investigation on the "BIOCHEMICAL GENETICS OF MUGIL CEPHALUS" from Cochin, Madras and Orissa. It is presented under the following major headings: Introduction, Review of Literature, Materials and Methods, Results, Discussions, Conclusions, Recommendations, Summary and References.The introduction gives a brief account of historical and modern back ground on the stock concept in fisheries research and management, followed by the importance and potential role of biochemical genetics in the identification of natural units of fisheries management. In the review of literature published reports relevant to biochemical genetics with special reference to that of general proteins and enzyme systems of fish populations were considered. A detailed account of the source of experimental specimens, mode of collection, transportation, sample extraction, gel preparation/gel electrophoresis, buffer systems, staining procedures of proteins/enzymes, standardization of experiments, interpretation of electrophoretic data using basic formulae etc. are given in the materials and methods section. Four important conclusions were drawn on the basis of the results of the present investigation. Three recommendations were also made on the basis of evaluation of the results.

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This thesis Entitled Studies on amylolytic bacteria in cochin backwaters.This thesis presents a detailed account of the disribution of amylolytic bacteria in water. sediment. fishes ( Etroplus suratensis and Liza parsia) • prawns ( Penaeus indicus and Metapenaeus dobsoni) and clams ( Sunetta scripta and Meretrix casta) from Cochin backwaters. genera-wise distribution of amylolytic bacteria, ability of selected strains to grow and produce amylase at various physico-chemical conditions. Regulation of amylase synthesis anrt characters of amylases producer by these halophilic bacteria.Amylolytic bacteria are distributed widely in water. sediment. fishes. prawns and clams of Cochin back waters. 53% of the total isolates tested were capable of producing amylase. Maximum number of arnylolytic bacteria were present in Metapenaeus dobsoni. In general, the gut region of aquatic animals harboured more amylolytic bacteria than the gill or surface. These bacteria may help in the digestion of starch present in their food.Presence of ions in the medium was found to be essential for growth and amylase production. It was found that this ionic requirement is not highly specific. Sorlium chloride could be replaced by potassium chloride. or magnesium chloride to some extent I without affecting growth and amylase production. The important function of these ions may be to maintain the osmotic balance between the cells and their environment.All the isolates showed the ability to grow and produce amylase using raw-starches from cassava. plantain and potato .This property suggests their role in the rdegradation of native starches in the environment

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Several studies on the biology and fisheries of mullets, particularly of M cephalus are now available. Different aspects of breeding, larval rearing, seed production, field culture and ecophysiology have also been investigated. However, information on the spermatogenesis in M cephalus as well as L parsia is scanty. Since an understanding of the reproductive strategies is an essential pre-requisite for evolving successful breeding programmes through artificial fertilization and gametic preservation, investigations on spermatogenesis in these species were taken up and the results are presented in this thesis. The thesis is presented in 9 chapters

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No serious attempt has so far been made in India to make use of the ‘Mussel watch’ concept as a useful tool for pollution monitoring of the marine and estuarine environment. The recently conducted 'National seminar on mussel watch’ by the Cochin University of Science and Technology (13-14 Feb, 1986) discussed the technical aspects related to mussel watch programme and the application of sentinel organism concept to the coastal areas of India. It is well known that the biological and physiological characteristics of the organism inhabiting tropical waters such as those prevailing in India, and the ecological as well as the environmental characteristics of temperate areas, where mussel watch programmes are already in existence differ greatly. So it is essential to adopt the techniques and standards developed for temperate species to the situations and conditions in India. In this context it is a prerequisite to collect information on physiology and other biological indices of stress of possible sentinel organisms like P.viridis. In consideration of the above, P. viridis which is a potential sentinel organism, is selected for the present study