Development of Bioreactors for Nitrifying Water In Closed System Hatcheries Of Penaeid And Non-Penaeid Prawns

In the present study the development of bioreactors for nitrifying water in closed system hatcheries of penaeid and non-penaeid prawns. This work is an attempt in this direction to cater to the needs of aquaculture industry for treatment and remediation of ammonia and nitrate in penaeid and non-penaeid hatcheries, by developing nitrifying bacteria allochthonous to the particular environment under consideration, and immobilizing them on an appropriately designed support materials configured as reactors. Ammonia toxicity is the major limiting factors in penaeid and non-penaeid hatchery systems causing lethal and sublethal effects on larvae depending on the pH values. Pressing need of the aquaculture industry to have a user friendly and economically viable technology for the removal of ammonia, which can be easily integrated to the existing hatchery designs without any major changes or modifications. Only option available now is to have biological filters through which water can be circulated for the oxidation of ammonia to nitrate through nitrite by a group of chemolithotrophs known as nitrifying bacteria. Two types of bioreactors have been designed and developed. The first category named as in situ stringed bed suspended bioreactor(SBSBR) was designed for use in the larval rearing tanks to remove ammonia and nitrite during larval rearing on a continuous basis, and the other to be used for nitrifying freshly collected seawater and spent water named as ex situ packed bed bioreactior(PBBR). On employing the two reactors together , both penaeid and non-penaeid larval rearing systems can be made a closed recirculating system at least for a season. A survey of literature revealed that the in situ stringed bed suspended reactor developed here is unique in its design, fabrication and mode of application.

Antiviral property of marine actinomycetes against White Spot Syndrome Virus in penaeid shrimps

Aquaculture farms, particularly in Southeast Asia are facing severe crisis due to increasing incidences of White Spot Syndrome Virus (WSSV). Actinomycetes have provided many important bioactive compounds of high prophylactic and therapeutic value and are continually being screened for new compounds. In this communication, the results of a study made to determine the effectiveness of marine actinomycetes against the white spot disease in penaeid shrimps are presented. Twenty-five isolates of actinomycetes were tested for their ability to reduce infection due to WSSV among cultured shrimps. When these actinomycetes were made available as feed additives to the post-larvae of the black tiger shrimp Penaeus monodon for two weeks and challenged with WSSV, the post challenge survival showed variations from 11 to 83%. However, six isolates have shown to be the most potential candidates for further study.

Marine yeasts as source of single cell protein and immunostimulant for application in penaeid prawn culture systems

The study revealed the potential of marine yeasts as a source of single cell protein and immunostimulant for prawns. Prawns fed with the selected marine yeasts were showing more growth compared to the control feed and commercial feed. Yeasts being rich with proteins, vitamins and carbohydrates serve as a growth promoter for prawns as being evidenced in this study. The better performance of marine yeasts, D. hansenii S8 and S100 and C. tropicalis S186 compared to S. cerevisiae S36 as a feed supplement is worth investigating. Besides being a rich nutritional source, yeasts act as immunostimulants by virtue of its high carbohydrate (Beta, 1-3 glucan) and RNA content. Beta, 1-3 glucan, a cell wall component of yeasts /fungi is the most commonly used immunostimulant in aquaculture. The present study shows that even the whole cell yeast could serve as a good immunostimulant when supplied through diet. Extraction of Beta-1,3 glucan results in the removal of nutrients like proteins, vitamins etc. from the cell biomass.Utilization of the yeast biomass as such in the diet would help perform a dual role as nutritional component and immunostimulant for aquaculture applications.

Molecular Biological investigations on viral diseases affecting farmed penaeid shrimps in Kerala

This thesis covers various aspects of viral diseases affecting shrimp aquaculture. The research component of this thesis can be divided into four areas. The areas covered are: I) A study to determine the prevalence of WSSV among the crustaceans in the Vembanad estuary, the shrimp aquaculture farms surrounding the estuary, and the sea off Cochin coast, India using two , sets of nested PCR primers. 2) An investigation to compare the sequence of six major structural proteins of WSSV; vp28, vp26, vp 19, vp68, vp281, vp466 from different geographical locations with that of an isolate from India. 3) Simultaneous occurrence of HPV, IHHNV, MBV and WSSV in postlarvae of P. monodon from hatcheries in India was monitored by Polymerase Chain Reaction. 4) A real time PCR procedure was developed for the quantitative analysis of WSSV infection. The viral load of postlarvae from hatcheries in Kerala meant for aquaculture was also determined using the quantitative PCR.

Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps

The constitutive production of AMPs in shrimps ensures that animals are able to protect themselves from low-level assaults by pathogens present in the environment. As these molecules play important roles in the shrimp immune defense system, the expression level of these AMPs are possible indicators of the immune state of shrimps. The present study also indicates the antiviral property of AMPs, especially ALF, stressing the importance of their up-regulation through the application of immunostimulants/probiotics as a prophylactic strategy in aquaculture. The present study shows that shrimp defense system is equipped enough to evade WSSV infection to a certain extent, when the animals were maintained on marine yeast and probiotic diet, whereas the control diet fed group succumbed to WSSV infection. This study reveals that marine yeast and probiotic supplemented diet can delay the process of WSSV infection and confer greater protection to the animals. Particularly, the protection conferred by marine yeast, C. haemulonii S27 and Bacillus MCCB101 were highly promising imparting greater hope to the aquaculture community to overcome the prevailing disease problems in aquaculture. It may be inferred from the present study that up-regulation of AMP genes could be effected by the application of immunostimulants and probiotics. Also, AMP expression profile could be used as an effective tool for screening immunostimulants and probiotics for application in shrimp culture. Ultimately, it is likely that no single compound or strategy will provide a solution to the problem of disease within aquaculture and that, in reality, a suite of techniques will be required including the manipulation of the rearing environment, addition of probionts as a matter of routine during culture, and the use of immunostimulants and other supplements during vulnerable growth phases. Finally, the development of good management practices, the control of environmental variables, genetic improvement in the penaeid species, understanding of host-virus interaction, modulation of the shrimp immune system, supported by functional genomics and proteomics of this crustacean, as a whole suggests that the control of WSSV is not far.

Marine Actinomycetes as Source of Antimicrobial Compounds and as Probiotics and Single Cell Protein for Application in Penaeid Prawn Culture Systems

This thesis Entitled Marine actinomycetes as source of antimicrobial compounds and as probiotics and single cell protein for application in penaeid peawn culture systems. Ocean harbours more than 80% of all life on earth and remains our greatest untapped natural resource. The study revealed the potential of marine actinomycetes as a source of antimicrobial compounds. The selected streptomycetes were found to be capable of inhibiting most of the pathogenic vibrios, whichis a major problem both in hatcheries and grow out systems. The bioactive principle can be incorporated with commercial feeds and applied as medicated diet for the control of vibrios in culture systems.The hydrolytic potential inhibitory property against pathogens and non—pathogenicity to penaeid prawns make the selected Streptomycesspp.an effective probioic in aquaculture. Since there is considerably less inhibition to the natural in pond ecosystem the microbial diversityis being maintained and thereby the water quality. Actinomycetes was found to be a good source of single cell protein as an ingredient inaquaculture feed formulations. Large amount of mycelial waste (actinomycete biomassO is produced from antibiotic industries and this nutrient rich waste can be effectively used as a protein source in aquaculture feeds.This study reveals the importance of marine actinomycetes as a source of antimicrobial compounds and as a probiotic and single cell protein for aquaculture applications.

Pathological Investigations in penaeid Prawns

The thesis embodies the results of the studies carried out on certain diseases affecting the commercially important penaeid prawns in the capture and culture fisheries of the southwest and southeast coasts of india during october, 1981 to april 1985.initially a survey is conducted to obtain information and to understand the commom diseases and abnormalities occurring in the penaeid prawms in nature and those farmed. A result of the survey then cases of diseases and abnormalities are reported. These include tumour like growth soft prawm syndrome, tail necrosis brown spot disease, red rostrum, ciliate infestation ,helminth parasitisation,metacercarial infestation and bopyrid infestation in the penaeid prawns such as penaeus indicus p. monodon , p. semisulcatus ,Metapenaeus dobsoni and m.affinis.The symptoms ,occurrence and incidence of each of the above cases are provided along with the information on environmental factors such as salinity,dissolved oxygen,temperature and ph of the water from the collection sites. The nature of the disease,the tissuse of the host that are affected by the infection or infestation or by the pathogen ,and the actors influencing the infection in each of the ten cases are studied histopathologically and discussed. In the light of the available published information, the control measures for the different diseases of penaeid prawns are presented and discussed.

Studies on the pathobiology of penaeid larvae and postlarvae

The thesis presents the results of the studies carried out on certain diseases encountered in the larvae and postlarvae of penaeid prawns raised in the hatcheries at Cochin, Madras and Mandapam Camp during September 1985- April 1988. In the preliminary survey carried out to understand the common diseases occurring in the penaeid larvae and postlarvae, seven cases of diseases and abnormalities were encountered. These included ciliate infestation, Nit_zschia closteriurn infestation, parasitic protozoaninfection, parasitic dinoflagellate infection, appendage necrosis, heteromorphic eye and abnormal eggs and deformed nauplii .The clinical signs, seasonal occurrence and incidence of each of the above cases were provided along with the information on environmental factors such as salinity, dissolved oxygen, temperature and pH of the rearing medium. The Thésis is presented in nine chapters. Chapter 1 surveys the literature on the diseases of penaeid larvae, postlarvae and adult prawns from India and abroad. This is followed by a chapter on the material and methods employed during the present investigation. In the third chapter, seven cases of diseases and abnormalities encountered in the larvae and postlarvae of Penaeus indicus and p. semisulcatus during the survey carried out in the hatcheries located at different centres of Central‘ Marine Fisheries Research Institute are presented and discussed .A bacterium responsible for appendage necrosis was isolated and its taxonomy was studied. It was Gram-negative, fermentative and motile rod. It was sensitive to vibriostatic compound, 0/129. This bacterium was found to be a new isolate of vibrio on the basis of its morphological, biological, physiological and biochemical characters and comparison of these characters with those described for other related vibrios. This new isolate of vibrio was deposited in vibro Referrence Laboratory, Centres for Disease Control, Georgia, U.S.A. and coded as vibrio sp. 2448-88.

Studies in the effects of hydrogen sulphide on the penaeid prawns of Kayamkulam lake, Southwest coast of India

The work presented in this thesis is centered mainly around delineating the toxic effect of hydrogen sulphide on penaeid prawns and understand its influence on the ecology of estuary. The present investigation also involved characterization of the effects of hydrogen sulphide on the growth and behavioural responses of Penaeus indicus. The test animals employed during the present study namely indicus and Metapenaeus dobsoni are both ecologically and economically relevant. The thesis embodying the details of the investigation has been organized into three chapters comprising Acute toxicity, influence of hydrogen sulphide on the ecology of estuary and effect of hydrogen sulphide on growth and substratum selectivity of penaeid prawn. Each chapter has been partioned into various sections as Introduction, Material and Methods, Results and Discussion for a lucid presentation of the subject matter.

Studies on the reproductive endocrinology of the penaeid prawn, Penaeus indicus H. Milne Edward

The present investigation has been carried out to understand the process and events leading to maturation of the ovary and testis in the Indian white prawn Penaeus indicus. The study includes the classification of the ovarian maturity stages based on its colour, gonadosomatic index, oocyte diameter and morphological changes in the oocyte. Further the process of oogenesis has been investigated using light and electron microscopic techniques. A histochemical study of the ovary has also been carried out to determine the sequence in which yolk substances are synthesized or sequestered in the oocytes and also to elicit the nature of the penaeid yolk material. The process of spermatogenesis and the development of the spermatophore has been studied in detail using light and electron microscopic methods. In addition a brief histochemical study on the testis was also made to understand the nature of the organic reserves in the sperm cells.

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.