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Subject: Fisheries × Author: KAU × End date: 2008 × Start date: 2008 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Reproductive biology of macrobrachium canarae ( tiwari, 1958 ) (decapoda, palaemonidae)
    (Department of Fishery Biology, College of Fisheries, Panangad, 2008) Sreedevi, K H; KAU; Jayachandran, K V
    The aim of this project is to introduce the freshwater prawn Macrobrachium canarae (Tiwari, 1958) as a candidate species in a community aquarium. The orange red shining spot on the second cheliped where the movable finger joins with palm makes it appealing in the aesthetic sense. This species is found to breed in captivity also. For the effective management of the prawn in the aquarium, a thorough knowledge on the various aspects of its reproductive biology is a prerequisite. The various aspects of reproductive biology dealt with are 1. Taxonomy 2. Sexual dimorphism 3. Breeding dress 4. Maturity stages and ovarian development 5. Fecundity 6. Moulting Since the species do not exhibit sexual dimorphism in size, it is difficult to identify male and female. The difference in colour of antennular flagellum between sexes becomes useful especially when they are bred in captivity. The data on maturity stages and also the time of ovarian development finds its use especially in the aquarium rearing. The fecundity studies gives an idea of the number of offsprings which could be produced from a single brood .
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    ThesisItemOpen Access
    Ovararian maturation, breeding and early embryonic development of an indigenous ornamental cyprinid of the western ghats - chela fasciata silas
    (Department of Fishery Biology, College of Fisheries, Panangad, 2008) Indira, Divipala; KAU; Anna Mercy, T V
    Chela fasciata is an indigenous ornamental cyprinid endemic to the Western Ghats of Kerala. It inhabits the riffle zones of River Bharathapuzha at Thootha. A total of 144 fishes (94 females and 50 males) ranging in size from 26.0 to 82.0 mm were collected from the wild and used for the study of reproductive biology. The gonads were quantified into six maturity stages based on external morphology as immature virgin, maturing virgin, early ripening, late ripening, ripe and partially spent. Studies on oocyte distribution of the six stages of maturity were done to understand the maturation of ova in the ovary. The ovaries of Chela fasciata showed asynchronous oocyte development. The oocyte development was classified into nine different oogenic stages namely, chromatin nucleolus stage, early perinucleolus stage, late perinucleolus stage, yolk vesicle stage, primary yolk stage, secondary yolk stage, tertiary yolk stage, migratory nucleus stage and mature oocyte). The first mature females appeared in the length group of 40 – 45 mm and males in the group of 25 – 30 mm. The size at first maturity for female was found to be at 45.75 mm TL (45 – 50 mm) and for males at 36.25 mm TL (35 – 40 mm). All the females were mature by 60.00 mm TL and the males by 45.00 mm TL. Based on the ova diameter frequency study of the ripe ovary, Chela fasciata was found to be a multiple spawner, with a protracted spawning season, the individuals spawning intermittently. Absolute fecundity of the fishes ranged from 2669 to 4437 in fishes of size range 49.5 mm to 82 mm TL. The number and size of eggs were found to be directly proportional to the size and age of the fish. Fecundity showed a positive linear relationship (5% level of significance) with the length and weight of both the fish and ovary. The embryonic development studies showed that the cleavage stage of the egg lasted for about 2 hrs 10 min., post fertilization. The inside egg embryo stage had lasted for 21 hrs, post fertilization. The eggs hatched at the end of 21 hrs, and the embryos emerged tail first. Pigmented eye was seen in one-day-old free embryo. Free embryo stage lasted for three days post fertilization. By the end of third day, the mouth developed, the yolk sac was empty and the exogenous feeding started, the free embryo entering the larval period. A complete understanding of basic reproductive biology of this fish will definitely help in the commercial production under captivity for the domestic and export market of this indigenous ornamental fish.
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    ThesisItemOpen Access
    Structure & functions of the accessory nidamental gland in the indian squid,loligo duvanuceli orbigny(mollusca:cephalopoda)
    (Department of Fishery Biology, College of Fisheries,Panangad, 2008) Gomathi, P; KAU; Rjashekaran Nair, J
    Females of the Indian squid, Loligo duvauceli in different stages of sexual maturity were collected during September-November, 2007. Mantle length of the ripe females was 16.22 ± 0.487 cm and body weight was 125.3 ± 8.628 g. Accessory nidamental glands (ANG) were conspicuous only in sexually maturing females. These paired glands were located at the anterior end of the nidamental glands (NG) and were closely associated with the ventral surface of the ink sac. The colour of ANG was orange red in mature specimens. The colour has been attributed to pigments of symbiotic bacteria. The ANG-somatic index of ripe females of L. duvauceli was 0.154 ± 0.024 %. Based on the morphological changes like gross size, coloration of the gland and also histological changes like formation, distribution, size and shape of the pigment granules during the course of maturation, the accessory nidamental glands were quantified into four stages namely immature, ripening, ripe and spent. Antibacterial activity of ANG-butanol extracts (2.5 g in 5.0 ml butanol) from different stages of maturity was studied. The extracts from ripe stage ANG showed antibacterial activity against gram negative bacterial strains, Escherichia coli and Pseudomonas aeruginosa, and gram positive bacteria, Staphylococcus aureus. Immature and spent gland extracts did not show any antibacterial activity. The ANG-butanol extract of ripe ANG showed an absorbance maximum at 498.5 nm, followed by shoulders at 528.0, 290.5 and 315.5 nm. In the case of immature stage an absorbance maximum at 285.0 nm was obtained, followed by shoulders at 340.5, 358.0 and 400.5 nm. For the spent stage the absorbance spectrum was very similar to the immature stage. The peak at 498.5 nm (2.597A) obtained for the ripe stage could be attributed to the presence of carotenoid pigments. The peak obtained at 286 nm for the different stages indicated the presence of peptides/ proteins. Thin layer chromatography of the ANG- butanol extract did not show the presence of polyphenols/flavonoids or quinones, whereas neutral lipid components such as phospholipids, cholesterol, free fatty acids, triglycerides, fatty acid esters, and cholesteryl esters were detected. The total free fatty acid (FFA) content in the ripe ANG was 16.0 ± 0.143 mg oleic acid/g tissue, whereas in immature ANG, it was 10.3 ± 0.114 mg oleic acid/g tissue. The FFA content was significantly higher in the ripe stage. Gas chromatographic studies of immature and ripe stages revealed the presence of a mixture of fatty acids. The total fatty acid content was 3.925 mg/g tissue in ripe stage and 0.704 mg/g tissue in immature stage showing the high gross value in the ripe stage. The quantum of the major four fatty acid (Palmitic acid, Oleic acid, Docosahexaenoic acid and Eicosapentaenoic acid) components was clearly found to be much more in the ripe stage than in the immature stage, especially the unsaturated fatty acids and may be the factors responsible for the antibacterial activity.
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    ThesisItemOpen Access
    Screening of lab-lab,selected mangrove plant and seaweed for antimicrobial compounds
    (Department of Aquaculture, College of Fisheries,Panangad, 2008) Pau biaklun, K; KAU; Devika, Pillai
    The present study aimed to find out the feasibility of using mangrove leaf, “lab-lab” and seaweed as a bioactive compound source and to evaluate the antibacterial activity of each in vitro against pathogenic bacteria. In vitro screening of the extracts of the seaweed viz., Gracilaria corticata, and the mangrove Avicennia officinalis by disc diffusion test showed species specific activity in inhibiting the growth of bacteria pathogenic to fish viz., Pseudomonas spp., Bacillus megaterium, Aeromonas hydrophila, Salmonella spp. and also E.coli. The solvents used were butanol, methanol, chloroform, acetone and water. The aqueous extracts of A. officinalis leaves showed very high activity against Bacillus, Salmonella and Aeromonas, the zones of inhibition being greater than or comparable to that obtained with the broad spectrum antibiotic chloramphenicol used in the study as a positive control. The butanol extract of mangrove leaf was active against E. coli. The butanol and aqueous extract of the bark of A. officinalis showed good activity against Salmonella and Bacillus, whereas in case of Gracilaria corticata, butanol, chloroform and acetone extracts showed considerable activity against Aeromonas, Salmonella and E. coli, respectively. However, extracts of “lab-lab” in the different solvents did not show any activity against the bacteria tested. Water was the best solvent to extract the antimicrobial compounds from the mangrove leaves while butanol was the best solvent medium for extracting the effective antimicrobial compounds from the marine algae Gracilaria. Phyto-chemical analysis of the aqueous extract of Avicennia leaves by thin layer chromatography to analyze the compound responsible for the antibacterial activity indicated the presence of a polyphenolic lipid quinone with isoprenoid side chains. Thus, present study shows the potential of using mangrove and seaweed extracts for development of antibacterial agents for use in aquaculture as an alternative to antibiotics.