Theses

Browse

Search Results

Now showing 1 - 9 of 13

Open 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 .
Open 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.
Open Access
Temporal variation in the hydrography and biodiversity of the Cochin backwaters of Puduveypu region.
(Department of Fishery Hydrography, College of Fisheries, Panangad, 2011) Trinayan Deb, Sarmah; KAU; Raman, N N
The study was carried out to find out the temporal variation in the hydrography of the Cochin backwaterS of Puduveypu region and to find out the richness of the biodiversity of the area. The study was conducted from April, 2010 to Apil, 2011. The present study was carried out to find out the temporal variation in the hydrography of the Cochin backwater of Puduveypu region and to find out the richness of the biodiversity of the area. The value of salinity in the backwaters of Puduveypu showed a wide fluctuation. The maximum value was recorded in the second half of January. The salinity showed considerable reduction during the period of March-April, 2011 due to Premonsoon showers. . Water temperature showed peak values during pre-monsoon period and with the onset of monsoon the value decreased. High pH was observed during the monsoon season while low values were observed during N.E. monsoon and pre-monsoon period. Alkalinity showed an increasing trend during the pre-monsoon, post monsoon and N.E. monsoon seasons but a decreasing trend was observed during monsoon season. Total hardness ranged between 22.22 mg CaCO3/l and 710.01 mg CaCO3/l. Dissolved oxygen showed high values during monsoon and post monsoon period. During the N.E. monsoon period the dissolved oxygen showed a decreasing pattern and reached a minimum of 2.1mg/l in the second half of February. The higher values of nitrate-N were observed during post monsoon and monsoon season. Seasonal variation of nitrite 133 was not that much pronounced. The phosphate value ranged between 2.2 μg at/l and 5.8 μg at/l during the study period. The maximum value of silicate-Si was recorded during the last phase of the monsoon. Turbidity ranged between 11.11 NTU and 40.4 NTU. It showed a negative correlation with transparency. Transparency value of the study region falls within a range of 30 cm. to 47 cm. Primary productions showed a wide range from 32 mgC/m3/day to 3707 mgC/m3/day. The highest value of chlorophyll was observed during the second half of July and the minimum value was observed during the second half of October. The sediment pH value ranged between 7.02 and 8.3 with an average of 7.78. The analysis revealed that sediment of the Puduveypu region contains maximum sand followed by silt and clay. Mangrove species like Rhizophora mucronata, Rhizophora apiculata, Rhizophora conjugate, Brugiuera cylindrical, Brugiuera gymnorhiza, Sonerasia caseolaris, Sonerasia alba, Avicennia officianalis, Exocearia agallocha, Acanthus ilicifolius, Clerodenterum innerme, Premma latifolia, and Acrostichum aureum were found in the study area. , Avicennia officianalis contribute 70% of the total population of mangrove. Penaeus monodon, P. indicus, Metapenaeus dobsonii, M. monoceros, Feneropenaeus indicus, Penaeus semisulcatus, Macrobrachium equidens, M. idella have been identified from the study area. Crabs in the study area include Scylla serrata, Scylla tranquebarica, Thalamita creneta, Charybdis annulata, Sesarma quadratum, Uca vocans. Bivalves includes Lamellidens 134 sp., Villorita Sp. and Cirriped in the study region include Balanus. 36 species of finfishes were collected during the study period. The fishes can be categorized into 10 order and 26 families.
Open Access
Studies on drying of fish using a BARC - TYPE solar dryer.
(Department of Processing Technology,College of Fisheries, Panangad, 2011) Vimaladevi, S; KAU; Sajan, George
A study was conducted with the aim of evaluating the drying efficiency of a newly designed solar dryer (modified BARC type) in comparison with conventional sun drying. The materials used for drying were beheaded prawn (Metapenaeus dobsoni) and salted fish (Cynoglossus macrostomus). Rate of drying was found to be influenced by the atmospheric temperature and humidity, either using dryer (test or by sun drying (control). In the case of prawn, the drying period was 7h by dryer compared to control which took about 10h whereas in the case of fish it was only 7h compared to control which took about 9h. Various parameters such as moisture content, water activity, TPC, TFC, TVBN content and PV, during drying were monitored. The quality variations in prawn or fish were significantly lower when dried using the solar dryer compared to direct sun drying. Sensory evaluation based on colour, odour, texture and taste, also proved that the solar dried samples were of superior quality compared to control. Sorption isotherm for test and control did not vary much in shape for both prawn and fish. This indicates that the effect of the type of drying on the bound water of the products. For conducting storage studies the dried prawn and dry salted fish, both test and control, were packed in low permeable polypropylene- polyamide bags and stored at room temperature for about 80 days. Quality parameters, viz., moisture content and water activity, TPC, TFC, TVBN content, PV and sensory evaluation based on colour, odour, taste and texture were evaluated during storage. Both test and control samples remained acceptable throughout the storage period. However, the quality of prawn or fish dried in solar dryer was found to be superior compared to their respective sun dried control samples. The additional cost was only Rs 2.40/ kg for dried prawn and Rs 2.00/ kg for dry salted fish. The equipment is recommended for small scale production of dried products.
Open Access
Influence of cryoprotectant levels on storage stability of surimi from a tropical fish, Nemipterus japonicus (Bloch) and quality of surimi-based products
(Department of Processing Technology, College of Fisheries, Panangad, 2009) Parvathy, U; KAU; Sajan, George
A study was undertaken with the aim of reducing the concentration of cryoprotectants in surimi without adversely affecting stability of the material during frozen storage. The concentration of sugar in commercially produced surimi is generally about 8% which may result in high sweetness in the products prepared. A tropical fish, Nemipterus japonicus (Bloch) was used as the raw material. Minced fish meat was strained, water leached, mixed with different levels (0%, 2%, 4%, 6% and 8%) of sucrose-sorbitol mixture in 1:1 ratio, quick frozen at -35 oC and frozen stored at -20 oC. Water leaching resulted in a slight absorption of water by meat and reduction in protein, fat and mineral contents. Surimi was found to have a moderately white colour. Sensory evaluation studies were conducted on three products, viz., sausage, patty and cake, prepared using surimi containing different concentrations of sucrose-sorbitol mixture. Sugar content varying from 0% (control) to 4% in surimi resulted in products that were more acceptable to the taste panelists compared to those prepared using surimi with 6% and 8% sugar mixture. A slight sweetness in the product (2% to 4% sugar in surimi) was more preferred by the panelists than their respective controls prepared using surimi containing no sugar. Frozen storage studies were carried out at -20oC on surimi treated with various concentrations of sugar mixture as mentioned above for a period of five months. pH and total plate count remained nearly steady for all sugar concentrations and throughout the storage period indicating insignificant microbial activity. Moisture content appeared to remain constant during storage, but decreased with increase in sugar concentration probably on account of addition of the sugar mixture. The salt soluble nitrogen content of surimi and gel strength of sausage prepared from it decreased with storage period in all surimi samples, and increased with sugar concentration, while expressible water content of the sausage showed an increasing trend with storage period and a decreasing trend with cryoprotectant concentration. These indicate a greater extent of protein denaturation occurring at low concentration of surimi samples. Sensory evaluation parameters - elasticity, sweetness and preference - remained more or less steady during storage. However, elasticity of sausage prepared from surimi with no cryoprotectant (control) and with 2% sugar level showed a decreasing trend with storage. Elasticity and sweetness increased while preference decreased with cryoprotectant concentration. Elasticity and gel strength seemed to be much lower for control (1.7 and 783.71 g.cm, respectively) compared to even the lowest concentration of sugar (2%) used (2.6 and 886.9 g.cm, respectively). From the study it may be concluded that a concentration of 2 to 4% sucrose-sorbitol mixture is well accepted by the consumers in products such as surimi sausage, patty and cake. At this range of concentration, surimi can be well-preserved in frozen condition at -20oC for at least five months.
Open Access
Ecology of mangrove patches in the Vembanad lake at Panangad
(Department of Fishery Hydrography, College of Fisheries, Panangad, 2009) Sukam, Monalisha devi; KAU; Raman, N N
The present study was carried out in mangrove area and backwater connected to the backwater through a sluice gate where mangrove patches are present. The study was undertaken in order to identify the floral composition, fishes, prawns, crabs and molluscs found in the area. The seasonal changes of hydrographical parameters like DO, pH, water temperature, alkalinity, salinity, primary productivity, silicate-silicon, phosphate-phosphorus, nitrite-nitrogen and nitrate-nitrogen and the sediment characteristics like sediment pH, total organic carbon, sediment texture were also studied. The mangrove species found in the study area were identified. Water temperature was minimum during south-west monsoon and maximum was during pre-monsoon. Average water temperature was lesser in mangrove area. Negative correlation was found between dissolved oxygen and all the nutrients. Through out the study period pH was alkaline. pH increased with increase in salinity and alkalinity. Dissolved oxygen was high during monsoon when compared with pre-monsoon period. It decreased with increased in salinity. Maximum salinity recorded during pre-monsoon when there was less freshwater intrusion. Average salinity was higher in backwater. Salinity showed negative correlation with all the nutrients. Alkalinity minimum value was observed during south-west monsoon it increases in post-monsoon and attained maximum during pre-monsoon. Alkalinity is higher in mangrove area. Primary productivity was maximum when light intensity was maximum. Average concentration of nutrients was higher in mangrove area. Maximum concentration was seen when inflow of freshwater was more. Sediment pH was minimum during pre-monsoon. Average sediment pH was lower in mangrove area than to backwater. Average Total organic carbon was maximum during post-monsoon in mangrove area and backwater. Sediment texture showed that substratum was silty sand in both the stations. When sand percentage increased total organic carbon was lowered. t-Test was done to compare significant difference between mangrove area and backwater. It showed that there was no significant difference with any of the hydrographical parameters between the two stations except primary productivity. ANOVA was conducted separately for two stations to compare significant difference between three seasons- monsoon, post-monsoon and pre-monsoon. In mangrove area pH and dissolved oxygen did not showed significant seasonal difference. In backwater water temperature, phosphate and nitrite did not show any seasonal difference. Dominant mangrove plants include Rhizophora mucronata, Brugiuera gymnorhiza, Brugiuera cylindrica, Avicennia officinalis, Acrostichum aureum, Acanthus ilicifolius. Prawns and crabs were abundant. Among prawns Fenneropenaeus indicus was caught through out the study period. Among crabs Scylla serrata and Uca spp. were commonly found. Balanus, Lamellidens sp., Villorita sp. were also seen in the study area. 30 species of fishes were identified from the study area and major contribution was by fishes belonging to the Order Perciformes. Mostly juveniles contributed to the fish catch.
Open 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.
Open 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.
Open Access
Structure and the seasonal changes of the macrobenthic community in relation to the hydrography of a prawn filtration pond
(Department of Fishery Hydrography, College of Fisheries, Panangad, 2009) Jayasree, P S; KAU; Raman, N N
Present study was carried out in the prawn filtration pond of the College of Fisheries adjacent to Cochin backwater to find out the seasonal variation of macrobenthos and to correlate them with the seasonal variation in hydrographical parameters and sedimentary characteristics of the pond. Fortnightly samples for hydrographical parameters, sedimentary characteristics and biological studies were collected during the period from October 2007 to September 2008. Hydrographical parameters like salinity, water temperature, turbidity, pH, total alkalinity, hardness, nutrients, dissolved oxygen, primary production, chlorophyll – a and transparency were observed. Polychaetes, tanaids, amphipods, bivalves and gastropods were the benthic groups obtained. Prawn juveniles and cumaceans encountered very rarely, during the study period were grouped as ‘others’. Among these gastropods, tanaids and polychaetes were the dominant forms. In the culture field, benthic populations were maxi mum during post monsoon months and showed a decreasing trend during pre monsoon and with the onset of monsoon it further decreased. Gastropods were the most dominant group observed during pre monsoon, forming 80% of total macrobenthos. Tanaids were the second major group and they were the dominant group during the post monsoon period forming 54% of total macrobenthos. Polychaetes were the third major group and constituted 35% of total macrobenthos during monsoon season and they were the second maximum during that period. In the culture field benthic abundance was found to be mainly influenced by substratum characteristics. Among the different hydrographical parameters studied for seasonal variation, water temperature, pH, primary production and chlorophyll were found to be significantly different. Among the sedimentary characteristics studied for seasonal variation, sediment pH was found to be significantly different.

Theses

Browse

Thesis Type

Type

Author

Date

Subject

Search Results