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ThesisItem Open Access Infestation of isopode parasites on prawns of the genus Macrobrachium Bate (Palaemonidae) of Cochin region(Department of Fishery Biology, College of Fisheries, Panangad, 2004) Regina Jasmine, M; KAU; Jayachandran, K VThe major objective of the research work is to study the taxonomy, species diversity, host specificity, intensity of infestation, length - weight relationship and reproductive biology of bopyrid parasite infesting the genus Macrobrachium Bate, 1868 of the Cochin region. Collections were taken from 3 stations Perumbavoor (Periyar River) and Panangad (Vembanad lake) for a period of 13 months (July 2002 to July 2003) and Champakkara (Vembanad lake) for a period of one year (October 2003 to September 2004). The study revealed that of the five species of Macrobrachium inhabiting water bodies of Cochin region, only two species were found infested with bopyrids. Macrobrachium idella was infested with Palaegyge alcocki whereas M. scabriculum with a new variety, P. alcocki var. novo cochinensis. This shows that bopyrid infestation is species specific. Diagnostic characters of both the parasite species are given in the text. Regarding the intensity of infestation, prawns from the Perumbavoor region of Periyar River had maximum infestation in comparison with other regions (Panangad and Champakkara). The infestation during different months also revealed the same trend. It indicates that infestation is more at the freshwater region than at the estuarine region. Relationships between length and weight of infested M. idella, P. alcocki separated from the host, total length of host and parasite, total length of male and female parasite, carapace length of the host and total length of male as well as female parasite are all statistically significant. . The study has brought out the ways of association of male and female parasites as well as attachment of female parasite to the host. Mature female parasite has been distinguished from the immature. Fecundity studies revealed that the number of eggs produced by the parasite ranges from 8148 (1 cm total length, 0.9 cm total width, 0.12 g total weight) to 29,683 (1.2 cm total length, 1.0 cm total width, 0.168 g total weight). Number of ova per milligram body weight ranged from 67.9 to 185.518 (126.709 average). Relationships between fecundity and total length, total weight, total width and total weight of brood of the parasite are all significant. The chapter on reproductive biology reveals important observations on marsupial brooding, ovulation, embryonic development and incubation, hatching and epicaridea stage of P. alcocki. The last chapter is on the effect of parasitism on the host. Here the aggressive behaviour of infested host, parasitic castration, degeneration of gills and secondary infections are dealt with in some detail.ThesisItem Open Access Temporal changes in the weather elements at Panangad region and their influence on the hydrography of a pond(Department of Fishery Hydrography, College of Fisheries, Panangad, 2004) Pronob Das; KAU; Raman, N NThe present study was undertaken with a view to finding out the seasonal and diurnal changes of weather elements at Panangad region, seasonal and diurnal changes in the hydrographic parameters of a freshwater pond and finally to understand the possible influence of weather elements on hydrographic conditions of a pond during the four seasons viz. southwest monsoon season (June-September), post monsoon season (October-November), northeast monsoon season (December-February) and pre monsoon season (March-April) at the College of fisheries, Panangad, Cochin. Meteorological data were collected at 03 UTC (0830 IST) and 12 UTC (1730 IST) daily during the period from June 2003 to April 2004. Water samples were collected from a pond every fortnightly to analyse hydrographical parameters. To study the diurnal variation, 24-hour observation were taken at an interval of 3 hrs, once for each season. Meteorological observation includes air temperature, maximum temperature, minimum temperature, total rainfall, relative humidity, cloudiness, wind speed and direction. Hydrographic parameters like water temperature, pH, transparency, water level, total alkalinity, primary productivity, dissolved oxygen, nitrate, nitrite, phosphate and silicate were estimated. There was a considerable seasonal variation in water qualities. The surface temperature closely followed the air temperature and exhibits a clear double oscillation. Low pH values confined to the southwest monsoon period were due to heavy rainfall. pH showed a positive relation with air temperature. At higher temperature evaporation was more and water level decreased, which leads to the higher concentration of plankton bloom and low level of transparency. Presence of nutrient elements in optimum concentration and there by production of phytoplankton and algal bloom may be the possible reason for the high productivity during the northeast and pre monsoon periods. The low values of primary production during southwest monsoon period (June to September) and in October might be due to cloudy conditions before and during the sampling, which reduced light intensity, and along with incessant rains cut down production. The high concentration of alkalinity during pre monsoon may be due to decrease in water level due to evaporation. The effect of rainfall in decreasing bicarbonates is well known. Dissolved oxygen was at the highest level in ponds during colder months and was due to low temperature and intense photosynthetic activities. Subsequent fall of dissolved oxygen in pre monsoon period is attributed to the death and decay of plankton and presence of other organic matter. The plankton population in the pond was highest during the month of December/January to April, coinciding with the higher concentration of alkalinity and nutrients. Diurnal variations in water temperature, pH, dissolved oxygen, alkalinity and primary productivity were well marked. Among nutrients phosphate, nitrate and nitrite did not show any specific pattern, where as silicate concentration showed well-marked short-term variation in all seasons. Weather elements showed significant relationship with many hydrographical parameters and the variations might be due to the combined effects of all those factors. The influence may be direct or indirect. Among the weather elements the influence of air temperature and rainfall was most prominent. The seasonal and diurnal changes in weather elements were equally important for the changes in hydrographical parameters. Shallow water bodies quickly react to the changes in weather elements.ThesisItem Open Access Quality and shelf life of fillets and cubes of a marine perch (Lethrinus lentjan (Lacepede,1802)) smoked by a mechanical smoker(Department of Processing Technology, College of Fisheries, Panangad, 2004) Sindhu, S; KAU; Krishnakumar, SA study was undertaken for the preparation of cubes and fillets from a marine perch King emperor or Pig face bream (Lethrinus lentjan, (Lacepede), 1802)). A method was standardised for preparation of smoked cubes and fillets. The parameters standardised were brining conditions, draining conditions, pre-drying conditions, smoking temperature and smoking time. The various brining conditions studied were brine concentrations of 10 %, 15 % and 20 % for brining times 15 min, 30 min and 45 min each. The various draining conditions studied were draining at room temperature and refrigerated conditions for periods of 15 min, 30 nun and 45 min. The pre drying conditions studied were pre-drying in tray drier and smoking kiln at 500e for 15 min, 30 min and 60 min. The smoking conditions studied were smoking at temperatures of so'c, 90oe, 1 oo'r: for 1 hr, 2 hrs and 3 hrs each. Salt content, moisture content and phenol content of the samples were analysed based on parameters studied in addition to sensory evaluation. Based on the test results the following treatments were selected viz., brine concentration of 10 % and brining time 15 min, draining under refrigerated condition for 30 min, pre-drying in tray drier for 30 min at 500e and smoking temperature of 800e for a period of 3 hrs. Smoked cubes and fillets were prepared using the standardised procedure and subjected to storage studies for a period of four months under different packing conditions viz., (i) smoked cubes and fillets packed in PE bags (ii) smoked cubes and fillets dried at 500e for 1 hr and then packed in PE bags and (iii) smoked tubes and fillets dried at 500e for I hr and then packed in paper bags. Quality changes during the storage period were monitored 15 days time intervals for parameters viz., moisture content, per cent free fatty acids, thio barbituric acid value, total plate count, total fungal count and sensory evaluation. Samples packed in paper bags remained acceptable only up to 60 days of storage and samples packed in PE bags were acceptable upto 90 days of storage.