Studies on osmoregulation in the penaeid prawn Metapenaeus dobsoni (Miers)

Metapenaeus dobsoni (Miers) is the most abundant species along the coast of Kerala. It is cultured extensively by adoption of traditional farming practices. The geographical location and water source determines the seasonal and annual environmental fluctuations the prawn farming systems experiences. The life cycle of the shrimp includes its migration to the coastal deeper waters for spawning and the immigration of larvae to the estuaries for growth. The survival of the species in such complex ecosystems is thus critical to its life cycle. The animal adapts itself to different environments through a physiological process known as osmoregulation. The present study on osmoregulation in the penaeid prawn Metapenaeus dobsoni was thus undertaken to understand the mechanism adopted by this species to survive in different environments. A number of experimental work have been conducted to understand the effect of salinity on the internal variations. However the effect of the complex environmental conditions as existent in nature on the osmotic variations in this species has not been dealt with in any of the earlier studies.

Studies on the freshwater copepod fish parasites of Kerala

Studies on parasitic copepods from freshwater fishes are still in its infancy. In recent years, there- is a renewed enthusiasm in the study of freshwater fish parasites due to rapidly increasing aquaculture practices. The importance of diseases and their control assumes great significance because of the adverse impact of diseases on fish production and its economy. Copepods are one of the most harmful parasites of freshwater fishes. Reports on the damages caused by copepod parasites from different parts on the world are increasing alarmingly. But the information on parasitic copepods of freshwater fishes in India is quite meagre. Knowledge regarding this group of parasites, their Biology and pathology from Kerala. is lacking. The thesis consists of five chapters. The first chapter is a general introduction which deals with the review of literature on various aspects of parasitic copepods viz; systematics, life history, host-parasite relationship, ecology, pathogenicity, prophylaxis and control measures. Systematics of parasitic copepods of freshwater fishes collected during the present study forms the second chapter. The third chapter deals with the life cycle study of the new Lernaeid copepod, Lernaea osphronemi. The fourth chapter contains host-parasite relationship. ecology and treatment of ‘the’ new species of Lernaea On Osphronemus goramy. General observations and a summary of the entire work constitute the fifth chapter

Studies on the physiology of moulting in the penaeid prawn, penaeius indicius h. Milne edwards

Penaeid prawns form the most economically significant group in the marine and brackishwater fishery resources of India. This particular group contributes about 62% of the total prawn landings of the country. At present prawns have assumed an important place especially as a commodity supporting an export trade of sizable magnitude. Considerable interest has been shown in the last decade to increase prawn production through various culture practices, mainly due to the high demand for good quality prawns for export coupled with the stagnant and even depleting nature of marine catches. Available informations suggest that among the 15 species of shrimps and prawns occurring in Indian waters, which are deemed suitable for aquaculture, the Indian white prawn §.indicus is identified as one of the most important commercial species. Considering the increasing importance as an accepted species for prawn culture, £.indicus was selected for the present study. In the life history of prawns, moulting is an important event, which enables the animal to achieve growth. This dynamic physiological event continues through out the life span ofthe prawn, linking almost all biological activities with this process. Hence, a good knowledge pertaining to the physiology of moulting is imperative to understand the growth process. This knowledge will be of great use in the scientific prawn farming, so as to achieve high prawn production.

Bionomics, Resource Characteristics And Distribution Of The Threatened Freshwater Fishes Of Kerala

The previous faunistic studies were concentrated.on the taxonomical and zoogeo— graphical aspects. These studies contributed to many new additions to the fish fauna of Kerala meanwhile many species described earlier are reported missing in recent years. Many fish species were collected only once or twice by scientists. Detailed information on distribution, habitat, feeding habits, reproduction, population size, etc. are available only with regard to a very few fish species. A meaningful assessment on the biodiversity status of the majority of freshwater fishes cannot be done for want of sufficient data base and therefore, no suitable conservation and management programmes are forthcoming for the protection and preservation of the unique fish germplasm resources of Kerala. The present study was conceptualised and undertaken mostly aiming at bridging these gaps by generating an authentic data base on the distribution, resource characteristics and bionomics of the threatened fishes inhabiting the rivers of Kerala. Osteobrama bakeri (Day) is an endemic fish having a very highly restricted and fragmented distribution in Periyar, Chalakudy, Kabini, Kallada and Meenachil rivers of Kerala. This belongs to vulnerable category and is locally known as Mullanpaval which is valued as food fish. Besides, due to its vibrant and attractive colouration and easiness for domestication, it has great potential for being propagated as an ornamental fish. Hitherto, no information is available on the bionomics and resource characteristics of this species. Studies on detailed life history traits are indispensable for fishery management, development of captive breeding technique and implementation of various conservation programmes. In the present study, a pioneer attempt is also made to investigate the life history traits, resource characteristics, proximate composition, etc. of O.baken'.

Effects Of The Piscicides, Mahua Oil Cake And Croton Seed On The Prawn Culture System

The present research programme envisages a comparative study of the effects of two piscicides of plant origin, viz., mahua oil cake, a derivative from the plant fig Iatifolia and croton seed, a product from the plant Croton tiglium. Although some reports on the effects of mahua oil cake and croton seed on fresh water pond culture systems are available, information on their effect on brackishwater culture systems are rather scanty This was the guiding principle for launching the present study It is hoped that the findings will enable aquaculturists to make use of the piscicides in a more rational and efficient way, and will go a long way towards realising the maximum return liom culture systems without hampering the environment. The thesis is presented in seven chapters such as Introduction, Review of literature, Materials and Methods, Results, Discussion, Summary and Bibliography

Giant heat dissipation at the low temperature reversible-irreversible transition in Gd5Ge4

The heat exchanged at the low-temperature first-order magnetostructural transition is directly measured in Gd5Ge4 . Results show that the origin and the temperature dependence of the heat exchanged varies with the reversible/irreversible character of the first-order transition. In the reversible regime, the heat exchanged by the sample is mostly due to the latent heat at the transition and decreases with decreasing temperature, while in the irreversible regime, the heat is irreversibly dissipated and increases strongly with decreasing temperature, reaching a value of 237 J/kg at 4 K.

studies on Prawn Gill Nets of The Kerala Coast

In the present study. extensive investigations were carried out on various factors affecting the selectivity of prawn gill nets with reference to material, mesh size, coefficient of hanging secolouration. Effect of tidal current on fishing height of prawn gill net and seasonal variation of catch during the course of these investigations were also studied.

Studies on the digestive enzymes of the Indian white prawn Penaeus indicus H. Milne Edwards

The efficiency of a diet not only depends on its nutrient composition and nutrient balance but also on the effective utilization by the animal. In the utilization of dietary nutrients, the digestive enzymes play the crucial role of catalysing the hydrolytic reactions, splitting the macromolecules into simple absorbable molecules. The activity of these biocatalysts is regulated by alterations in pH, temperature, substrate type and concentrations, and also by the presence of activators and inhibitors. Thus any shift from the optimum conditions necessary for these enzymes may affect their activity, thereby correspondingly modify the digestibility of the nutrients supplied to the animals. Thus, investigations on the important digestive enzymes and their preferential conditions of activity are essential, so that the results obtained could be used in rationally adjusting the quality and quantity of feed supplied to the different stages of prawns In India, directed research on nutritional physiology and biochemical approaches to digestion in commercially important prawns is taken up_ only recently, and the field is still in an infant stage. In view of its emerging importance it is identified as an area of priority and the present investigation has been carried out on the Indian white prawn Penaeus indicus

Studies on The Ecology And Production of Algae in Prawn Culture Systems

Existing method of culture were largely based on empirical knowledge. Lacking a scientific basis as such methods did, they were often wasteful and suffered severe limitation. Modern methods of fish and prawn culture based on scientific research, have revolutioned the industry in recent years and not only extended its scope to cover the whole country but led to increased fish and prawn production. An understanding of the biological capability of the water in the perennial and seasonal culture ponds, and the nature and extent of the influence of the abiotic factors on the production of organisms in the primary level of food chain would contribute to effectively implement management measures in the stocking strategies and in the evaluation of economics of production of prawns. It is against this background that the present topic of investigation "Studies on the ecology and production of algae in prawn culture systems” was selected.

Nature and Ecological significance of Nutrient Regeneration in Different Prawn Culture Fields

The present work "Nature and Ecological Significance of Nutrient Regeneration in different Prawn Culture Fields" was undertaken to understand the seasonal variation of nutrients, nutrient cycling and primary productivity of the prawn culture systems. The main emphasis was to find the qualitative and quantitative estimates of distribution of total phosphorus, inorganic phosphorus, organic phosphorus, total nitrogen and nitrogen fractions in the water. The effect of nutrient cycling on primary productivity and concentration of metals also form one part of the study. The entire thesis comprise of only one major chapter with subchapters such as, Introduction (I), Review of Literature (2), Material and Methods (3), Results (14), Discussion (5), Executive Summary (6) and Biblio~ graphy (7)

Studies on the female reproductive physiology of the prawn, Macrobrachium idella (Hilgendorf, 1898)

’l‘he reproductive physiology of the female palaemonid prawn M. idella has been investigated by adopting a comprehensive approach to the problem. The major aspects of the study included investigations on breeding biology and process of oogenesis, variations in the biochemical components in relation to maturation, neuroendocrine relations and control over reproduction, and artificial insemination. The prawns used in the present study were procured from Vembanad Lake at Panavally village - a place nearly 20 km. away from Cochin. The studies were carried out using standard histological and biochemical methods. The modern technique of electroejaculation was adopted for extrusion of spermatophores in artificial insemination experiment.

Studies on the evaluation of different sources of proteins, carbohydrates and mineral requirements for juvenile penaeid prawn Penaeus Indicus H. Milne Edwards

In India, directed research on penaeid prawn nutrition was taken up only recently when the aquaculture of prawns gained momentum. One of the important penaeid prawns sought for culture and has great potential is Penagus indiggs, H.Milne Edwards. The Central Marine Fisheries Research Institute working on different aspects of culture of this species over the past one and half decades, has developed a hatchery technology for mass production of its seed and has suggested several improvements on its farming in the grow-out systems. One of the areas of active research in this direction has been on the nutrition of the species with a view to develop suitable feed not only for hatchery production of seed, but also in the field culture. As part of this investigation, the present study, on the evaluation of different protein and carbohydrate sources and mineral requirements for the juvenile E, indicus was taken up and the results obtained are embodied in the thesis

Studies on the toxic effects of selected heavy metals in the freshwater mussel lamellidens corrianus (lea)

Industrialisation affects air, water, and soil. Industrial effluents which enter the aquatic environment either by direct disposal or through run off, affect living organisms at morphological and physiological levels. In any living tissue toxic materials exert their effects first at molecular and biochemical levels (Robbins and Angell, 1976). Most of the industrial effluents contain elevated concentrations of organic and inorganic chemicals capable of eliciting stimulatory or inhibitory effects on the metabolism of aquatic organisms. Heavy metals form an important group of environmental pollutants. Effects of pollution on the aquatic environment by heavy metals have received considerable attention in recent years due to their toxicity even at very low levels, persistence in the environment, and chances of getting biomagnified. A pollutant that does not affect a particular process under normal unstressed condition may affect the ability of the animal to adjust to changing environmental conditions which ultimately decrease its chances of survival (Thurberg et al., 1973

Systematics and pathogenicity of vibrionaceae associated with the larvae of macrobrachium rosenbergii in hatchery

The great potential for the culture of non-penaeid prawns, especially Macrobrachium rosenbergii in brackish and low saline areas of Indian coastal zone has not yet been fully exploited due to the non availability of healthy seed in adequate numbers and that too in the appropriate period. In spite of setting up several prawn hatcheries around the country to satiate the ever growing demands for the seed of the giant fresh water prawn, the supply still remains fear below the requirement mainly due to the mortality of the larvae at different stages of the larval cycle. In a larval rearing system of Macrobrachium rosenbergii, members of the family Vibrionaceae were found to be dominant flora and this was especially pronounced during the times of mortality However, to develop any sort of prophylactic and therapeutic measures, the pathogenic strains have to be segregated from the lot. This would never be possible unless they were clustered based on the principles of numerical taxonomy It is with these objectives and requirements that the present work involving phenotypic characterization of the isolates belonging to the family Vibrionaceae and working out the numerical taxonomy, determination of mole % G+C ratio, segregation of the pathogenic strains and screening antibiotics as therapeutics at times of emergency, was carried out.