PhD Thesis

Browse

Now showing 1 - 20 of 109

Effects of a pyralid pest on productivity of duckweeds in pond ecosystem
(University of Dhaka, 2015-05-06) Belal, Shahnaz Imrana
There are numerous instances of plant-Animal relationships which are ecologically friendly and significantly useful to the humans. The aquatic plant Duckweed and its pest (The pyralid insect) bear of the same interactions. In this study different biotic aspects were examined to clarify critical interactions of this relationship. This was aimed to establish a technique to examine bioresources in pond ecosystem. The objectives of the study were selected to evaluate biomass development of duckweed (Spirodela Polyrhiza). Life cycle and behavioural activities of its insect pest (S occidentals) was examined. Abundance of adults and abundance of larval and pupal stage was also examined. Record was maintained in nature of injury caused by the insect pest on the duckweed productivity. Various procedures and the sampling methods were innovated by the EBBL were used to carry out the research work. The research stations was in the Mirzapur Kumudini Hospital Complex, in Tangail District (in PRISM farm). Some experiments have been conducted in the Zoological Garden, Carzon Hall, in Dhaka University campus. In the experiment, Duckweed biomass growth development, the result was vary significantly in inorganic and organic pond, and biomass was doubled in eight days in both ponds. Duckweed Biomass growth development were followed by the method used by (Khondoker 1993) Life cycle observation, incubation period for hatching varies form 4-7 days. Egg hatching was higher in summer and lower in winter. Larval period lasts twelve days to more than one month. Pupation occurred within a cocoon inside the case, pupation period lasted for 4-7 days. The adults emerge from the pupa (within 2-4 days).Life cycle observations were followed by the methods using by Tuskes (1977) Adult abundance was significantly high in August and October and lower in January in Inorganic pond and an adult abundance were more in April and less in January in Organic pond. Adult distribution were followed by the methods of Lavery and Costa (1973) Infestation was calculated both in the fronds and roots of the Duckweeds in both ponds. The infestation was significant on the roots but it was not significant on the fronds in Organic pond. In loss assessment of Duckweed growth, it was found that; growth rate was highly affected, in the Inorganic and Organic pond. Larval/Pupal case making process had significant impact on duckweed productivity. Measurements of the Duckweed infestation and loss estimation were followed by the method used by Denis. S. Hill (1997) Finding of the research will also play a significant role in augmentation of rural economy of Bangladesh. But it needs awareness regarding the use of Duckweeds by taking scientific care of its association in the aquatic ecosystem.
Molecular typing of dengue virus isolated from field caught mosquito specimens by reverse transcriptase polymerase chain reaction (rt-pcr)
(University of Dhaka, 2015-05-20) Nazneen, Shaila
The Dengue viruses are borne by the Aedes mosquito. They cause dengue fever in most tropical areas of the world. The detection and successful typing of dengue virus (DENV) from field caught Aedes mosquito is important for virological surveillance and implementation of epidemiologic control measure. We have applied a rapid and sensitive, nested reverse transcription-polymerase chain reaction (RT-PCR) assay for the type-specific detection of dengue viruses in artificially infected and in field caught mosquitoes for first time in Bangladesh. Small scale bionomics study was done in few selected areas of Dhaka city to help find the recent dengue prevalent season, dengue vector breeding sites and the peak season of vector population. Findings of bionomics study have increased the chance of getting dengue infected mosquitoes from field. In bionomics study of Ae. aegypti higher number of mosquito population (85.15% eggs, larvae or pupae) were found in artificial container than in natural container (14.85%), indicating recent creation and availability of huge breeding ground for Aedes aegypti. Increased use of non biodegradable plastics, pot gardening, water logging and water storage habit of Dhaka city dwellers may have influenced higher mosquito densities by providing many more breeding sites. Larvae survey showed the Breteau Index of 20-40, well above the risk level for dengue virus transmission and the post monsoon period (August to October) was found to be the most affected period for larval growth. The Indoor resting adult populations start rising from August and the peak mosquito population and higher biting rate were found from September to November, which was consistent with the larvae survey. Field studies were conducted during November-December 2010, 2011 and from July to December 2012. Adult Aedes aegypti mosquitoes were caught from selected dengue prevalent areas of Dhaka city and tested for the presence of dengue virus by ELISA and RT-PCR method. The RT-PCR assay was sensitive enough to detect dengue virus in lab infected mosquito- thorax pool. Almost all ELISA positive mosquito specimens were found to be positive for dengue virus by RT-PCR (90% sensitivity compared to ELISA). Approximately 4.8%, (9 out of 188) mosquito pools (9-13 mosquitoes /pool) were found to be positive for dengue viruses. Of the nine RT-PCR positive Ae. aegypti pools six pools were (66.66%) positive for dengue virus 3 (DEN3), two (22.2%) were positive for DEN 2 virus and only one (11.11%) were positive for dengue 4 (DEN 4) viruses. No DEN1 virus positive pool could be recorded during this study. The predominant virus type responsible for the current dengue fever is DEN 3 and multiple virus serotypes also co-circulating in Dhaka city. Majority of the dengue virus-positive mosquitoes harbored DEN-3 virus, which had been the predominant dengue virus type responsible for the local dengue epidemic since 1964. Multiple serotypes were found in Dhanmondi R/A (serotype 3 and 4) and Mirpur (serotype 2 and 3). DEN-3 alone was detected in Rampura and DEN-2 in Dhaka University Campus and no dengue virus was detected in Shegunbagicha. Ae aegypti caught at the five indoor stations had MIR (minimum infection rate) ranging from 0.00-1.63 per 100 mosquitoes with an MIR of 0.72 for the combined stations. Dhanmondi residential area showed the highest (1.63) and Shegunbagicha showed the lowest (0.00). Dengue positive mosquito pools were found between end of the September to mid October in three dengue prevalent seasons 2010, 2011 and 2012. These findings give us impression that the predominant perhaps the most virulent serotype virus type responsible for the current dengue fever is DEN-3 and multiple virus serotypes are also co-circulating in Dhaka city. We found that the overall rate of dengue virus infection per 100 Ae. aegypti females during the study period was as high as 0.72, giving us an impression that a low grade infection and transmission is currently present in Dhaka city. Evidence of more than one viral serotypes should be taken as a warning that outbreaks of DHF might occur in the future, although a low grade infection and transmission is currently present in Dhaka city. RT-PCR based surveillance of dengue viral infection in Ae. aegypti mosquitoes could serve as an early warning monitoring system of dengue outbreak.
Effects of Leucaena leucocephala (Lam. de Wit) leaves and seeds on Channa punctatus (Bloch and Schneider) and Oreochromis niloticus (Linnaeus)
(University of Dhaka, 2016-06-07) Begum, Tasmema
To investigate the effects on Channa punctatus (Bloch and Schneider) and Oreochromis niloticus (Linnaeus) after feeding Leucaena leucocephala (Lam. de Wit) leaf and seed for using as fish feed. The food was given at the rate of 2% of the body weight of fish. The observed amounts used in the bioassays were calculated in gm/kg body weight. The diet was formulated containing different levels of L. leucocephala leaf 25%, 30%, 35%, 40% and seed 20%, 25%, 30%, and 35% with small fishes. The experimental diets were given to the fishes divided into several groups on the basis of leaf and seed levels for two months. The effects of the L. leucocephala leaf and seed were considered as behavioral, physical, haematological and histopathological changes in C. punctatus and O. niloticus. The effects observed in behavior of C. punctatus and O. niloticus due to L. leucocephala leaf and seed were loss of appetite and slow movement. The physical changes of C. punctatus and O. niloticus due to L. leucocephala leaf and seed were observed i.e. lesions on skin and on caudal region, erosion of fins, puffed and loose scales, and exophthalmus. Haematological parameters (TEC, TLC, thrombocyte, lymphocyte, monocyte, eosinophil, basophil, Hb,Hct, MCV, MCH and MCHC) and biochemical parameters (protein, albumin, globulin, glucose, urea, creatinine and cholesterol) of C. punctatus and O. niloticus were determined after feeding L. leucocephala leaves and seeds. All the haematological parameters of 25% leaf group, 20% and 30% seed group of C. punctatus and 35% seed group of O. niloticus were positively correlated with control group. Positive correlation was observed in biochemical parameters of all groups of C. punctatus and O. niloticus compared with control group. In case of L. leucocephala leaf, lymphocyte and eosinophil, total protein, albumin, globulin were highly significant in C. punctatus whereas thrombocyte, lymphocyte, neotrophil, eosinophil, protein and albumin were highly significant in O. niloticus at the 5% level of significance. In case of L. leucocephala seed, albumin of C. punctatus and eosinophil of O. niloticus were highly significant at the 5% level of significance. The effects of feeding L. leucocephala leaf and seed on the number of eggs of C. punctatus and O. niloticus were highly significant at the 5% level of significance. The histopathological changes found in tissues i.e. eye, gill, muscle, stomach, intestine, liver, kidney and gonad of the experimental fishes. The effects were observed specially at higher percentages 35% and 40% of the L. leucocephala leaf and 30% and 35% of seed. The histopathological changes in testes and ovaries of C punctatus and O. niloticus in this experiment at 25%, 30%, 35%, 40% L. leucocephala leaf and 20%, 25%, 30% and 35% seed groups showed the decreasing trend of tertiary oocyte, spermatid and spermatozoa with the increasing of percentages of L. leucocephala leaf and seed level.
Epidemiology of malaria in Bangladesh: detection and identification of genetic and molecular variation in Plasmodium falciparum
(University of Dhaka, 2016-06-08) Alam, Mohammad Shafiul
In the present study, different aspects of malaria in Bangladesh were studied including its epidemiological aspects, knowledge, attitude and practices of the people; development of two high level molecular diagnostic methods for the most virulent malaria parasite (Plasmodium falciparum ) followed by its genetic diversity. In the epidemiological study during 2010-13, a total of 1,64,055 malaria cases were reported from 13 endemic districts of Bangladesh. The overall mean female: male ratio of annual malaria incidence was1:1.42. Malaria caused by P. falciparum was found dominant in Bangladesh which was 94.2% of total malaria cases. Only 5.5% cases were reported to be caused by P. vivax. Remaining infection was caused by P. falciparum and P. vivax mixed infection. A total of 99 patients died during this period (2010-13). Quiet opposite to the malaria incidence, death of female (51) was slightly more than death of male (48). Highest number of death was 37 in 2010 followed by 36 in 2011.1
Rodent population outbreaks in relation to bamboo flowering in the Chittagong hill tracts, its impacts on crop production and environment
(University of Dhaka, 2016-06-08) Chakma, Nikhil
In 2006 to 2010 rodent population outbreaks resultant from the 50-year cycle of bamboo flowering were reported in Mizoram, India, the Chittagong Hill Tracts, Bangladesh, and Chin State, Myanmar. The ecological dynamics between rodent population outbreaks and bamboo flowering were studied in Ruma upazila of Bandarban district from March 2009 to December 2011. Small mammal trapping (March 2009 to December 2011) in the villages of Basatlang, Munlai, Mualpi and Neweden was carried out to understand the dynamics of rodent populations in different habitats. The highest percentage of rodent species was captured at community households, followed by bamboo forests, crop field and outside around villages. Ecological survey of bamboo flowering and bamboo seed fall in 2009 found that there were highly significant differences in partially rodent eaten seeds per square meter by month (p=.0001) and positively correlated between total numbers of seed fall and partially rodent eaten seed (r =.611). In 2010 bamboo seed fall survey also found positive correlation (r =.417) between total numbers of seed fall and number of rodent damaged seeds in response to cut, burned and normal bamboo forest. Crop damage assessments found that trap barriers were effective to protect crops from rodent damage during the rodent outbreak. Knowledge, attitude and practice surveys among six ethnic minorities covering 180 households revealed that they had little knowledge about rodent management in field crops and majority of households had severe rodent damage during rodent outbreaks. The study confirms that massive bamboo seed fall increases food availability for rodents, rodents do indeed eat bamboo seeds and the long availability of seed leads to population outbreaks. Particularly Rattus rattus was able to breed for 4-5 months in the forest with animals migrating out in to farmers’ fields as the bamboo seed germinated, causing crop losses of 80-100%. Shortening the time of rodent breeding was possible by cutting and/or burning the bamboo forest at the time of flower initiation as this led to a significant delay in seed production. Implementing large scale bamboo clearance could help prevent the development of population outbreaks or reduce their severity. Although farmers did not feel competent or knowledgeable about rodent management, their main coping strategy of planting earlier ripening rice crops in order to harvest before rodent outbreaks develop, is a sound strategy that should be encouraged during outbreak years. Research on increasing the yield of earlier ripening crops could help manage food insecurity during rodent outbreaks. Trap barrier systems were effective, but implementation costs are currently too high for individual farmers to benefit. Community trapping at the household level was effective for managing post-harvest damage and other household level damages. Although implementation costs are low and reasonable, community trapping requires good organization and leadership to be sustainable.
Prevalence of Entamoeba histolytica and Giardia lamblia infection among diabetic and non diabetic patients of Bangladesh
(University of Dhaka, 2016-08-28) Siddiqua, Tahmina
The present study was conducted on 697 diabetic and 603 non-diabetic peoples (aged 25-75 years) in the Immunology Laboratory, Institute of Health Science (BIHS) Hospital, Mirpur, in Dhaka to investigate their association with protozoan infestation. The use of appropriate technique plays an important role in the detection of the parasitic infections. ELISA with blood samples, formol-ether concentration technique (F-ECT) and zinc sulphate method (Z-SFM) were applied to faecal samples for the detection of prevalence of Entamoeba histolytica and Giardia lamblia. Out of 697 diabetic patients, by ELISA 15.93% and 17.65% were found infected by E. histolytica and G. lamblia; while out of 603 non-diabetic individuals, 27.53% and 28.03% were infected by E. histolytica and G. lamblia; respectively. According to the results of F-ECT on diabetic patients, 26.83% and 28.41%; 34.66% and 34.99% were found among non-diabetic individuals infected by E. histolytica and G. lamblia; respectively. According to the results of Z-SFM, on diabetic patients 12.05% and 13.34%; 15.09% and 16.09% were found among non-diabetic individuals infected by E. histolytica and G. lamblia respectively. A specimen was considered positive for E. histolytica and G. lamblia if either cysts or trophozoites or both stages were present. Double parasitic infestation (8.03%) was found in diabetic patients and 13.10% was found in non-diabetic individuals. By these methods (ELISA, F-ECT and Z-SFM techniques), it reveals that, males were more infected than females. It was also observed that prevalence was higher among 25-45 years than old aged group (above 55 years). By ELISA method, out of 697 diabetic blood samples, 18.68% of symptomatic types and 12.91% of asymptomatic types were positive for E. histolytica antibody. Similarly, 31.45% of non-diabetic symptomatic types and 21.21% of asymptomatic types were positive for E. histolytica antibody. Out of 697 diabetic blood samples, 21.15% was positive in symptomatic types and 13.8% in asymptomatic types for G. lamblia antibody, 31.18% of non-diabetic symptomatic types and 22.94% of asymptomatic types were positive for G. lamblia antibody. By F-EC technique, 31.87% of diabetic symptomatic types and 21.32% of asymptomatic types were positive for E. histolytica. Similarly, 37.63% of non-diabetic symptomatic types and 29.87% of asymptomatic types were positive for E. histolytica. Among diabetic 30.49% of symptomatic types and 26.13% of asymptomatic types were positive for G. lamblia. Among non-diabetic individuals, 38.71% of symptomatic types and 29% of asymptomatic types were positive for G. lamblia. By Z-SF method, 13.46% of symptomatic diabetic patients and 10.51% of asymptomatic types were positive for E. histolytica. Similarly, 19.35% of non-diabetic symptomatic types and 8.23% of asymptomatic types were positive for E. histolytica. Among diabetic patients, 14.56% of symptomatic and 12.01% of asymptomatic types was positive for G. lamblia. Similarly, 20.16% of non-diabetic symptomatic types and 9.12% of asymptomatic types were positive for G. lamblia. Considering the age groups, in non-diabetic individuals, the highest prevalence of E. histolytica was 38.05% in the age group of 25-35 and in the case of G. lamblia, it was 40.13% found in the age group of 35-45 years detected by F-ECT. In comparison of three techniques of blood and faecal samples, in single and double parasitic infections, the prevalence always found higher among the non-diabetes than the diabetic patients. The seasonal variation of parasitic infestation was higher during rainy season and lower in winter. It revealed that, F-ECT is most suitable method for detection of single and as well as double protozoan infections and is recommended as the best technique to get the concentration of the parasites present in faeces. Z-SFM used to diagnose infection with E. histolytica and G. lamblia, which is a quick and comparatively simpler examination and gives a precise and reliable diagnosis. The ELISA technique is the best of all techniques, which represents the present infection as well as the recent infection of amebiasis and giardiasis.
Population, breeding and conservation of Bengal monitor, Varanus Bengalensis in Bangladesh
(University of Dhaka, 2017-04-09) Dey, Santosh Kumar
The study was conducted on, “Population, Breeding and Conservation of Bengal monitor, Varanus bengalensis in Bangladesh” from May 2011 to November 2014 at (1) Hazratpur and Rasulpur village, Hazratpur Union Parishad, Mithapukur, Rangpur (HU, MR); (2) Jahangirnagar University Campus and its adjacent area, Pathalia Union Parishad, Savar, Dhaka (JUC); (3) Jamuna Resort, Durgapur Union Parishad, Kalihati, Tangail (JR, T); (4) Dhaka Zoo and National Botanical Garden Mirpur Model Thana, Mirpur Dhaka (DZ & NBG); (5) Kaltapara and Bostall Village, Jampur Union Parishad, Sonargaon, Narayangonj (SN); (6) Ghorashal Power Plant, Ghorashal Municipality, Palash, Narshingdi (GPP, N) and (7) Animal Garden, Dhaka University (AG, DU). The estimated highest population density (34.5/ km2) was found in Durgapur Union, Khalihati, Tangail and the lowest (3.41 km2) was found in Mirpur Model Thana, Mirpur, Dhaka. Among eleven categories of habitats, the highest percentage of population was noted in garbage (20.1%) followed by drain (15.5%), banks of ponds and lakes (10.8%), cultivated field (9.3%), bamboo shoots and bushes (9.1%), marshland (8.6%), open space (7.5%), underground space (7.2%), sloping ground (5.5%), on the trees (5.1%) and old graveyards (1.3%). The breeding season started in July to September and ended in March-April. The nest building period was from September to October. The Bengal monitors preferred to build their active nests in termite mounds. Diameter, circumference, depth and height from the ground of the active nests were 33.6±2.9 cm, 105.6±9.2 cm, 23.2±1.1 cm and 28.1±2.7 cm respectively. The mean clutch size was 24.6±7.11 (n = 182). The length, width, girth, weight and volume of the eggs were 5.93±0.19 cm, 3.95±0.22 cm, 12.6±0.52 cm, 41.5±1.7 g and 51.4±1.8 cm3 respectively Morning and afternoon temperature of the active nests were 18.5±4.90C and 25.9±5.30C respectively. The morning and afternoon humidity was 90.8±4.0 % and 54.1±7.7 % respectively. The incubation period was 194.8±1.79 days. The length and weight of hatchlings were 23.8±0.69 cm and 17.9±1.03 g. at the time of hatching respectively. In the of sixth, twelfth, eighteenth, twenty fourth and twenty seventh month, the length and weight were 64.4±3.9 cm, 320±61.9 g ; 93.8±5.9 cm, 927.5±154.2 g ;105.9±6.6 cm, 1651.9±282.8g ; 112.9±9.2 cm, 2302.5±427.3 g and 115.3±9.8 cm, 2632.7±503.9 g respectively. The hatchlings consumed 4.9%, 7.87%, 6.6%, 5.3%, 4.3% and 4.9% of food at the age of one, six , twelve, eighteen, twenty four and twenty seven month respectively in relation to the body weight . The hatchlings shaded their skins at a time rather than part by part. The survival rate of hatchlings was 68.16% in relation to the number of eggs laid. Within concentrated areas, the population density was higher (44.0 individuals/km2) in protected zones, than in the non-protected zones (13.2 individuals/km2). They acted as natural scavengers in the environment to remove the dead and decaying materials. Percentages of scavenging individuals in drains and garbage dumps were 36.7 and 63.3 respectively. Scavenging was mostly observed between 9:00 am to 11:00 am. The number of snake biting decreased when the density of Bengal lizards increased. Bengal monitors control rat population and balancing beetle and earthworm population. The reasons for the declining of the population of Bengal monitors were due to the destruction of habitats (59%), followed by destruction of nests, eggs and hatchlings (16%), killing of adults (11%), predation (8.%), road kill (4%) and effects of pesticides (2%). Through creation of awareness during the study period, it was noted that the general people changed their impression to monitors. At the start of the research, 58.4% people showed negative impression to monitors, on the other hand, at the end of the research, 94.1% people became sympathetic to monitors.
Development of sustainable cage cultre practice for tilapia (oreochromis niloticus l.) in riverine ecosystem
(University of Dhaka, 2017-06-01) Hossain, Md. Robiul Awal
This study was conducted in the Dakatia river at Echoli and Roghunathpur site of Chandpur, Bangladesh during the year from 2010 to 2011 which consisted of four trials under the two experiments on stocking density and feeding regime of tilapia (Oreochromis niloticus) in cage culture. Each experiment include two trials with complete randomized design (CRD). Floating net cages, having an area of 3m×3m×2m in each were installed in both sites of the Dakatia river. The initial average weight (g) of 32.31±9.59, 28.92±8.37, 36.20±11.64 and 20.76±6.14 were stocked for each treatment of the stocking density trial-1, stocking density trial-2, feeding regime trial-1 and feeding regime trial-2 respectively. The duration of each trial was 120 days having three treatments with three replications to assess sustainable cage culture practice for tilapia in the riverine ecosystem. The physicochemical parameters of cage water were monitored fortnightly. Final weight (g), weight gain (g), relative growth rate (%), specific growth rate (%/day), food conversion ratio and survival rate (%), gross production (kg/cage), net production (kg/cage), net profit (Tk/cage), benefit cost ratio of tilapia in cages were determined after completion of the each trial. Growth parameters such as weight gain (g), relative growth rate (%), specific growth rate (%/day), and food conversion ratio was also measured monthly basis. The physicochemical parameters of cage water were found suitable for cage fish culture in all the trials. Correlations of different physicochemical parameters were related to each other and the relationship was found significant in most of the parameters. All growth parameters of stocking density trial-1 revealed highly significant differences (p < 0.001) among three treatments. The maximum survival rate was found in T (85.61%) followed by T 2 (81.92%) and T (67.58%) respectively, having highly significant differences (p < 0.001). The highest benefit cost ratio was achieved in T 3 (1.20) followed by T 2 (1.19) and T 3 (0.88) but highest profit was found in the T 2 1 . In stocking density trial-2, it was exhibited that all growth parameters were highly significant differences (p < 0.001) among three treatments. The highest survival rate was found in T 1 (97.92%) followed by T (86.73%) and T (84.38%) respectively which was highly significant differences (p < 0.001) among them. The highest benefit cost ratio was achieved in T 3 1 (1.81) followed by T (1.37) and T 3 (1.07) respectively. The net profit was found similar as highest in T and followed by T 2 and T . In case of feeding regime trial-1 the final weight, weight gain and specific growth rate showed significantly different (p < 0.05) among the treatments, while the relative growth rate and food conversion ratio was found highly significant differences (p < 0.001) among three treatments. The highest survival rate was found in T 3 1 1 2 (97.33%) followed by T (96.88%) and T (96.44%) respectively which was not significantly different. The maximum benefit cost ratio was achieved in T 2 1 (1.71) followed by T 2 (1.36) and T (1.17) respectively, which was similar as achieved net profit of the three treatments. The final weight, weight gain and specific growth rate of feeding regime trial-2 were exhibited significant differences (p < 0.01) among the three treatments, whereas the relative growth rate and food conversion ratio was found highly significant differences (p < 0.001) among three treatments. The highest survival rate was found in T 2 (97.22%) followed by T 1 3 (97.00%) and T (96.66%) respectively but not significantly differ with each other. The highest benefit cost ratio was determined in T 3 (1.93) followed by T 2 (1.44) and T (1.25) respectively, which was similar as determined net profit. The proximate composition of used floating feeds was found suitable for tilapia culture but the crude protein (%) showed some differ from labeled crude protein. It could be concluded that stocking density of 50/m 1 3 and feeding regime with 4% of body weight feed through the culture period was found suitable for practice tilapia cage culture in the riverine ecosystem.
Population genetic structure of freshwater mud eel, Monopterus cuchia (Hamilton, 1822) in Bangladesh
(University of Dhaka, 2017-06-04) Miah, Md. Faruque
n this study, population genetic structure of freshwater mud eel, Monopterus cuchia in Bangladesh was observed by RAPD and RFLP assay for finding a superior population with high genetic diversity. Some associated observations including rearing, breeding biology and artificial breeding has also been performed. First experiment was conducted to study the effect of different environments such as House tanks, Earthen ditches, Plastic tank and Back yard tanks on rearing and production performance of freshwater mud eel, M. cuchia where different types of biological food in different amounts were used, except the earthen ditch-2 (control). 40 fishes (approximately 1kg in weight) were stocked into each of the environment and the highest mean of final length (32.89±2.65423) and final weight (109.69±2.92777) were obtained in earthen ditch-1. The weight gain in length 17.78 ± 0.24 and in weight 85.07 ± 0.15 with 92.5% survival and production (4.07kg) were also highest in earthen ditch-1. On the other hand, the lowest mean growth considering final length (28.45±2.80092) and weight (67.24±3.79328) were recorded in house tank-2 while the weight gain in length (11.86 ± 0.26) and in weight (41.84 ± 0.59) were also observed in house tank-2 with the production of 2.02kg by 75% survival. Based on Pearson correlation coefficient no significant correlations were found between lengths and weights of fish in different culture regimes. In second study a successful protocol was developed to identify male and female M. cuchia through external morphology, internal anatomy and histological analysis. Furthermore, breeding biology of freshwater mud eel, M. cuchia was considered in terms of gonadosomatic index, length-weight relationship of gonad, ova diameter and fecundity. The ova diameter was recorded from 0.3 mm to 4.30 mm and the individual fecundity was recorded from 155 to 1495 while relative fecundity was found from 2.64 to 12.45. A peak of GSI was observed 2.14±0.2 in male and 5.1 ±1.09 in female. Artificial breeding of fish was practiced but unsuccessful spawning was recorded through different inducing agents in captive conditions. In this study, 16S rRNA and glutamine synthetase gene was used for identification of this fish and molecular standard was recorded 250bp length by 16S rRNA gene and 541bp length by the partial sequence of glutamine synthetage gene. In this study, genetic diversity of freshwater mud eel was studied by RAPD assay and a total of 735 bands with 228 polymorphic loci were detected while polymorphisms were revealed by all eight arbitrary primers. The highest and lowest number of bands was recorded 120 and 49. Thirteen different groups of inter individual pair wise similarity and 36 groups of genetic diversity were measured whereas the lowest and highest genetic distance was found 0.58 and 0.97 respectively while the average genetic diversity was found 0.8173716. The highest and lowest Nei’s genetic similarity values were recorded 0.60 and 0.06 respectively and linkage distance was computed between the ranges of 3.6 to 6.24 which were generated six clusters by 11 clades. Intra and inter population genetic diversity was analyzed by the same eight RAPD primers considering 2 populations (Tanguar Haor=P1 and Hakaluky Haor =P2). A total of 353 bands with 147 polymorphic loci were detected in P1 whereas a total 371 bands with 153 polymorphic loci were found in P2. Polymorphisms were revealed by all the primers in P1 and P2 while a single monomorphic locus were seen in P1 resulting 95% and 100% polymorphism showed in P 1 and P2 respectively. 9 and 13 groups of inter individual pair wise similarity were found in P1 and P2 respectively considering averages 6.46 and 6.08. The 27 and 29 different genetic distance values were recorded in P1 and P2 while the average genetic distances were calculated 0.80 in P1 and 0.816 in P2 respectively. Nei’s genetic similarity in P1 was ranged 0.11 - 0.58 with 34 diverse values and in P2 it was ranged between 0.06 – 0.54 with 36 different values, and in an average it were originated 0.323 in P1 and 0.301 in P2 respectively. A total 35 and 18 different linkage distances were estimated in P1 and P2 respectively whereas the average linkage distances were found 5.115 and 5.141 respectively in P1 and P2. A genetic relationship was made by using linkage distance where five clusters were created from 5 clades in both P1 and in P2. Based on allelic information, the frequency of q alleles were recorded highest in both the populations than the frequency of p alleles. Based on the intra-locus gene diversity the average highest gene diversity was observed in P2 in most of the primers. However, the average gene diversity was found highest 0.164635264 in P2 and lowest 0.150829501 in P1. Genetic diversity of glutamine synthetage gene was analyzed in this freshwater fish with two restriction enzymes of +CfrI and +Hpy178III while both the enzymes were digested the size of 541 bp and polymorphism was detected in terms of wild type homogygotes, polymorphic homozygote and heterozygosity. The genetic diversity was observed by using the RFLP band analysis and four different groups of individuals were identified with the p-values of 0, 0.033, 0.05 and 1 respectively whereas different distances were found among the groups. Intra and inter population genetic diversity of M. cuchia was analyzed by using same fragment of glutamine synthetage gene by the same enzymes considering the ecological habitats of Tanguar Haor (P1) and Hakaluki Haor (P2) resulting less polymorphism was observed in P1 than P2. Considering different genetic distances two groups of individuals were identified very close with 0.02 P-value in P1 and five groups were revealed in P2 from very close to large distances. The frequency of q alleles were recorded highest in both the populations than the frequency of p alleles except the enzyme +Hpy178III in P2 (0.433). However, intra-locus gene diversity was found highest in P2 by both the enzymes than P1. Inter population differentiation for one locus (gst = 0.5299) shows significant delineation between populations in allele frequencies and it can say that a high percentage of genetic distance is distributed among two populations. F-statistics was analyzed for observing the genetic structure of populations where degree of allele frequency (FIT = 0.7606) and differentiation of allele frequencies between two populations seems greater (FST = 0.1439), with only a moderate effect of random mating were observed within the populations (FIS = 0.7204). From the above records, polymorphism was found in glutamine synthetage gene of this fish and generally higher polymorphism was observed in P2 as well. Overall finding of this research is concluded that the earthen ditch was found one of the suitable culture environments of M. cuchia and live feed was recorded suitable for obtaining better growth. Breeding biology of this fish was considered with development of a successful protocol to identify male and female as prior knowledge for breeding program, and unsuccessful spawning was recorded through inducing agents. A molecular standard was recorded for species identification of this fish. Final observation in both cases of RAPD and RFLP study higher genetic diversity were observed in general as well as at population level though P2 was recorded stronger genetic status than P1. The research is indicating the good genetic status of this fish in Bangladesh particularly in the ecological habitats of Sylhet. e
Assessment of large mammals of the Chittagong Hill Tracts of Bangladesh with emphasis on tiger (Panthera tigris)
(University of Dhaka, 2017-06-13) Chakma, Suprio
Biodiversity assessment is the first step of conservation and monitoring of an ecosystem. Scientific information like ecological requirements of a species helps conservation practitioners to monitor the changes over time, but it is almost true that assessment of each and every species in an area is not necessary and impractical. Globally tiger is an endangered species and tiger density strongly correlated with prey densities. The Chittagong Hill Tracts (CHT) of Bangladesh is considered as Tiger Restoration Landscape. Neither tiger nor prey abundance has been assessed for the CHT. The overall goal of this study was to assess the conservation potential of medium (> 5 kg) to large mammals (>20 kg) across the CHT with special emphasis on tiger (Panthera tigris). A total of 3800 km² area has been surveyed from March, 2010 to July 2011. I have collected presence absence data using signs (tracks, scats, scrapes) survey and analysed using programme PRESENCE by applying occupancy models and figures using programme R. In addition to signs survey camera trap survey was also conducted, and compared the effectiveness of two methods. Relative Abundance Index (RAI) and activity patterns of medium to large mammals were quantified. Potential conservation areas assessed following The Nature Conservancy (TNC) guidelines and finally formulated conservation recommendations.
Growth performance of Indian major carps on different feeds and cost-benefit analysis
(University of Dhaka, 2018-02-04) Hassan, Mohammad Kamrul
A study was conducted to establish an optimal methods under two feeding regime (poultry waste and supplementary) for the culture of Indian major carps by comparing the growth patterns and to develop a cost efficient feed and feeding technique through cost benefit analysis for future use in Bangladesh. Static 5.00 mg/L dissolved oxygen content was the remarkable observation during the investigation period in both study ponds except March’14 at treatment I and treatment II. The ponds were slightly alkaline with pH values ranged from 6-7 Hardness, alkalinity and ammonia showed narrow difference in their mean value. The average survival rate of different species was found satisfactory and comparatively higher in treatment I and were significantly different from treatment II .The highest survival rate was 92.67% for Labeo rohita and the lowest was 87.66% for Cirrhinus mrigala. In treatment II, the range was 76.33% to 84.66%, the highest survival rate was 84.66% for L. rohita, and the lowest was 76.33% in C. mrigala. The present study indicated a non significant difference in the growth rate among the individual species in treatment I and II. Highest SGR was calculated as 3.28% in C. catla in treatment I and lowest 1.47% in C. mrigala in treatment II. The eighteen months investigation showed the gross final weight gain were for Labeo rohita, Catla catla and Cirrhinus mrigala were 1520gm., 1860gm. and 1470gm, in treatment I and 870gm., 920gm. and 855gm. at treatment II, respectively. Monthly mean growth gain (gm.) of the species were 92.04±75.38, 100.06±93.79 and 79.41±75.51 at treatment I and 45.96±58.19, 47.61±52.09 and 61.94±97.07 at treatment II. The main growth performance factor length-weight relationship was calculated with the average data based on measurements of 50 fishes of each species and observed a significant difference between two treatment groups. Monthly mean growth of L. rohita, C. catla and C. mrigala showed increased rates with onset of rainy period and decreased growth and decreased rates during the winter period. Most of the months showed significant correlation. All the species showed allometric growth patterns in two feeding regimes with different developmental variances depending on influence of physicochemical and biological influences. vi Statistically all independent predictor variables viz. Temperature °C, DO mg/L, CO2 mg/L, pH, Hardness, Alkalinity mg/L, NH3 mg/L, Premix vitamin (kg), Fishmeal (kg) in treatment I and temperature °C, CO2 mg/L, pH, Hardness, NH3 mg/L, Alkalinity mg/L in treatment II, explains 79.6%, 81% and 80.60% and 29.39%, 29.60% and 29.39 effect on length development variance of L. rohita, C. catla and C. mrigala in treatment I and treatment II, respectively, which are not significant as indicated by 2.73, 2.09 and 2,90 F values and 0.098b, 0.080b, 0.085b P values and 0.680, 0.701 and 0.649 F values and 0.664a, 0.656a and 0.664 P values. The same predictor explains 89.20%, 87.60%, 89.20% and 39.00%, 39.30%,41.70% effect on growth development variance of L. rohita, C. catla and C. mrigala in treatment I and treatment II, respectively, which are not significant as indicated by ANOVA F values -5.78, 4, 92, 5.80 and 0.050a, 0.023a, 0.15a P values and 1.02 ,0.87, 1.80 F values and 0.46b, 0.54b, 0.30b P values. Biological variable planktons viz. Chlorophyceae, Cyanophyceae, Euglenophyceae, Rotifera, Cladocera, Copepoda, Ostracoda, Nauplius as predictor explains 40.40%, 40.570% and 40.40% effect on variance in length development of L. rohita, C. catla and C. mrigala which were not significant as indicated by ANOVA F values 0.678, 0.682 and 0.677 and P values 0.702b, 0.700b and 0.730b in treatment I. On the other hand 51.30%, 49.70%, 52.10% effect on variance in length development of L. rohita, C. catla and C. mrigala, which were not significant as indicated by ANOVA F values 0.678, 0.682 and 0.677 and P values 0.702b, 0.700b and 0.730b in treatment II. In the same way biological variable as predictor explains 42.70%, 42.80% and 42.90% effect on variance in weight development of L. rohita, C. catla and C. mrigala which were not significant as indicated by ANOVA F values 0.747, 0.747, 0.759 and P values 0.655b, 0.655b, 0.653b in treatment I. A little higher 51.30%, 49.70%, 52.10% effect on variance in weight development of designated species, which were not significant as indicated by ANOVA F values 0.678, 0.682 and 0.677 and P values 0.702b, 0.700b and 0.730b in treatment II. Standardized coefficient values indicates that none of the physicochemical and biological plankton variables, contributes the prediction of length and weight development of L. rohita, vii C. catla and C. mrigala and explains an equal non-significant combined influence on the length and weight development of species under investigation. Biological ecto and endo parasitic variables showed more less same prevalence and infestation with seasonal variation and host selection in I and II Treatment group. Total 8.0% and 24.0% L. rohita, C. catla and C. mrigala faced the paroasitic death during Winter, 10.0% and 30.0% faced during Summer and 16.0% and 38.7% during Monsoon in treatment I and in treatment II, respectively and showed significant (p<0.05) correlation between the two groups. The study showed that C. catla made the highest contribution to the total yield in two treatments. Contribution of L. rohita was about 32.84% in treatment I and 34.74% in treatment II. C. catla Contributed 35.83% in treatment I and 33.77% in treatment II. C. mrigala was found to contribute 31.31% in treatment I and 31.47% in treatment II. Gross production of individual species of fish was calculated from the average final weight multiplied by the actual numbers of fish harvested. In treatment I, net weight was calculated 407.56, 490.14 and 372.21 in L. rohita, C. catla and C. mrigala and 198.15, 204.06 and 181.39 in L. rohita, C. catla and C. mrigala in treatment II. It is obtained from the present investigation that total production of treatment I and treatment II were 1269.91 kg. and 583.60 kg. Unpaired t-value at 0.001 levels indicate final production of L. rohita, C. catla and C. mrigala of two groups in feed feeding system are positively correlated without influence of feed. The key financial and economic indication of two feeding regime ponds. The cost for the production was 2,16,471 Tk. in treatment I and 39,952 Tk. in treatment II. Net return was 3,95,677 Tk. and 1,66,582 Tk. in treatment I and treatment II, respectively. Calculated total net return of profit was 1,79,206 Tk. in treatment I and 1,26,630 Tk. in treatment II. Percentage of profit was 83 % in treatment I and 317% in treatment II. Cost and benefit ratio was 121:100 in treatment I and 32: 100 in treatment II. Cost profit ratio and benefit cost ratio were positively significant (P=0.05 and P=0.001). The profit function analysis clearly showed that the production and profitability of the system can be increased further by judicious application of fertilizer and feed. Other variables like viii labour showed negative returns and hence farmers have to carefully manage labour inputs. With the availability of the large amount of feed ingredients in Bangladesh, significant improvements in fish production can be achieved. It is likely that the current level of profitability would encourage more land to be converted to aquaculture, particularly by using the vast amount of waste land available in Bangladesh. It was also observed that there were many possibilities to increase production further by introducing and adopting better management practices.
Occurrence of helminth parasites and their developmental stages in snails from different regions of Bangladesh
(University of Dhaka, 2018-02-05) Roy, Shuvra
Helminth infection study of freshwater molluscs in and around Dhaka, Khulna and Kishoreganj region was conducted at twenty three locations which include eleven from Dhaka region, six from Khulna region and another six from Kishoreganj region from different ponds during July 2011 to June 2013 on a once in a month basis. A total of three species of freshwater molluscs belonging to two families that comprises of Viviparidae, Ampullariidae and three genera (Bellamya, Pila, Brotia) were found in the pond eco-systems. Physico-chemical parameters like pH, temperature, dissolved oxygen, electrical conductivity and its variation at all the collection sites were analyzed. As the molluscs are intermediatory hosts between the parasites and animals, an overview study was also carried out on the known molluscs’ various parasites and their diseases. Bangladesh has been virtually unexplored with respect to its trematode fauna, the sampled freshwater snails from temporary and permanent ponds were collected. Helminth infections of 3 snails species, viz., Bellamya bengalensis, Brotia costula and Pila globosa. Samplings were done primarily on monthly basis. 31,717 snails (B. bengalensis, 10,915; B. costula, 9,961; P. globosa, 10,841) were autopsied, of which 4,099 were infected by helminthes (12.92%). The infection was eight types of cercariae (belonging seventeen species), one nematode adult morpho-type, two Cestodes, one Pentastomida and one Turbellaria. Among the hosts, prevalence of trematode infection was highest in B.bengalensis (14.7%), followed by P. globosa (12.95%) and B. costula (10.95%). Contrary to the general knowledge, infection of snails by nematode parasites, though rather poor in diversity, was higher (1.24-4.55%) than that by the DST (12.92%). Seasonally, DST was more prevalent in the rainy season, whereas nematodes were during the summer. With respect to parasites harboured, Pila globosa was the most diversified refusing all the 3 infector groups. Altogether screened 31,717 individuals of three freshwater snail species (Bellamya bengalensis, Brotia costula and Pila globosa) for shedding cercariae. Collectively, eight morphologically distinguishable types of trematode cercariae were found: ii Parapleurophocercous cercariae; Pleurophocercous cercariae; Xiphidiocercariae cercariae; Furcocercous cercariae; Echinostome cercariae; Amphistome cercariae; Renicolid cercariae and Cotylomicrocercous cercariae. Out of 23 locations the parasitics collected from Pila globosa other than trematode and nematode were two Cestodes, one Turballaria and one Pentastomida. Overall prevalence was found in August to September (1.03-2.26%) in 2011-2013. In the present study monthly fluctuations in the cercarial prevalence were observed due to the variations in the temperature, rainfall and dissolve oxygen of each month. The occurrences of cercariae are maximum in August to September (18.18% - 28.57%) and minimum if February (3.45-8.33%) which is dealt with elevated temperature, rainfall and DO level in the Dhaka region. Whereas, In Khulna and Kishoreganj region the maximum prevalence was in August to Semtember (14.29% - 37.5%) and no infection was found in some months. It is made clear from the results that more number of species related with low DO content. It can be inferred from the above points that DO content plays a vital role in affecting the population dynamics of a particular species than the other physico-chemical factors like pH, temperature and EC. Moreover the molluscan population is abundant in a place where the aquatic plants are available in diverse forms. Since there is not much variation in pH, temperature, EC and salinity in the collection sites, they do not have much influence in the availability of specimens in this present study. Through this analysis, it is inferred that the possibility of variation in pH, temperature, EC can play a vital role in the life cycle of any plant or animal group and when it is moderate or in low, it cannot have much influence on the population dynamics. In 2011-12, occurrence of trematode parasite in Bellamya was significantly higher than that of Brotia and Pila (p<0.05). Moreover, in 2012-13 occurrence of trematode parasite in Bellamya was significantly higher than that of Brotia and Pila. On the other hand, occurrence of this parasite in Bellamya found in 2012-13 was significantly higher than that of 2011-12. No significant different was found in Brotia and Pila in this two years (p>0.05). The prevalence of trematode parasites in Bellamya, Brotia and Pila in 2011-2012 and 2012-2013 sampled from 23 different regions were determined. Each year was divided into three different seasons (Rainy, winter and summer) where the incidence of the parasites in rainy season in most of the cases was significantly higher than that of other seasons. However, the prevalence in summer (in most of the regions) was significantly higher than that of winter. iii The overall natural environmental parameters varied within overlapping ranges among the ponds. Water temperature ranged between 4.7°C and 38°C depending on the day and time of collection. The hydrogen ion concentration was within the range providing protection for the aquatic life (7.2 to 9.8). The concentration of dissolved oxygen showed generally low in some locations due to pollution load (Dhaka region) and higher (> 7.0 mg/l) levels and exhibited a strong negative association with water conductivity (rs = -0.665, p < 0.05). The data identified the correlation between temperature, pH, EC, DO, rainfall and prevalence of parasites in snails of three different regions in 2011-12 and 2012-13 academic years. Sometimes positive correlation with significant level (p>0.05) and without significant level were observed. Significantly positive correlation was found between temperature and prevalence of parasites in snails of Dhaka regions in 2011-12 (p<0.01).Positive correlation was also found between % occurrence and pH, EC, DO and rainfall, but was not significant (p>0.05). Positive correlation was found between temperature and prevalence of parasites and rainfall and prevalence of parasites in snails of Dhaka regions in 2012-13 (p<0.01).Positive correlation was also found between % occurrence and pH, EC, and DO, but was not significant (p>0.05). Also the significant positive correlation was found between temperature, EC, rainfall and prevalence of parasites in snails of Khulna regions in 2011-12 (p<0.01).Positive correlation was also found between % occurrence and pH, but was not significant (p>0.05). Also the significant positive correlation was found between temperature, EC, rainfall and prevalence of parasites in snails of Khulna regions in 2012-13 (p<0.01).Positive correlation was also found between % occurrence and pH, but was not significant (p>0.05). Positive correlation was found between temperature, EC (p<0.05), rainfall and prevalence of parasitesin snails of Kishoreganj regions in 2012-13 (p<0.01).Positive correlation was also found between % occurrence and pH, but was not significant (p>0.05). Also the positive correlation was found between temperature, EC (p<0.05), rainfall and prevalence of parasites in snails of Kishoreganj regions in 2012-13 (p<0.01).Positive correlation was also found between % occurrence and pH, but was not significant (p>0.05).
Performance and quality assessment of salt curing of Taki (Channa punctatus), Shol (Channa striatus) and Tengra (Mystus tengra)
(University of Dhaka, 2018-02-07) Farid, Farzana Binte
Salting of fish is widely used as one of the most important low-cost traditional method for fish-preservation and considered as a concentrated source of nutrients to all categories of people throughout the world including Bangladesh. Salt-cured fishes are highly appreciated because of their characteristic taste, texture and storage stability. So, attempts have been made in the present study to preserve three freshwater fishspecies of Bangladesh viz., large size fish Shol (Channa striatus, Bloch; 1801), medium size fish Taki (Channa punctatus, Bloch; 1793) and small size fish Tengra (Mystus tengra, Hamilton- Buchanan; 1822) with five different types of salt-curing method viz., Dry salting (DS), Pickle curing (PC), Brine salting (BS), Sun-dried salting (SDS) and Turmeric treated sun-dried salting (SDS+T). Studies were conducted on their sensory (characteristics & scores), proximate (moisture, protein, fat, ash) chemical (salt, TVB-N, FFA, pH) and bacteriological (SPC & HBC count) quality assessment during storage period both at room (26-320C) and refrigeration (40C) temperature using standard methods of analyses. Important mineral composition e.g. Ca, Mg, Fe, Cu Zn, and Mn were also determined in fresh fish and freshly processed salted fish-products. The present study showed that, the content of moisture, protein, fat, ash, TVB-N (Total Volatile base-Nitrogen), FFA (Free Fatty Acid), pH and SPC (Standard Plate Count) of freshly collected shol fish was 77.03±0.12%, 19.52±0.07%, 1.93±0.07%, 1.44±0.11%, 4.41±0.01 mg/100g, 0.6±0.06%, 6.9±0.06, and 2×105 cfu/g; taki fish was 78.65±0.07%, 16.89±0.10%, 2.50±0.06%, 1.36±0.11%, 3.43±0.02 mg/100g, 0.5±0.10%, 7.0±0.06 and 1.1×105 cfu/g and tengra fish was 74.27±0.07%, 16.96±0.07%, 6.04±0.06%, 2.67±0.08%, 4.27±0.02 mg/100g, 0.9±0.21%, 7.0±0.10 and 5×105 cfu/g respectively. Fresh shol, taki and tengra fish had Ca 11.2, 16.35 and 22.025; Mg 10.125, 9.425 and 11.4; Fe 1.475, 1.275 and 2.25; Cu 0.7, 0.65 and 0.55; Zn 0.25, 0.425 and 1.275; Mn 0.1, 0.05 and 0.125 mg/100g of fish respectively. ‘Salt ripening’ of five different types of salted shol, taki and tengra was obtained by assessing changes in salt penetration rate and its effect on moisture content, fluid loss pattern in fish muscles and percent weight loss of fishes during ripening period. After salt-ripening moisture (%) content, pH value, SPC (cfu/g) and HBC (cfu/g) load decreased whereas protein (%) (except BS tengra), fat (%), ash (%), salt (%) and FFA (%) value increased in salted fish samples when compared to the fresh fish samples. Salt (NaCl) content in freshly prepared salted products ranged between 13.77% & 17.10%. Preferability study was also done with the taste testing of ‘Fish-curry’ prepared from 5 different types of freshly processed salted Shol, Taki and Tengra fish-products so that these kinds of new products could find good market. Taste testing study showed the greater acceptability of turmeric treated sun-dried salted (SDS+T) shol, taki and tengra fish over the others. It was also observed that salted fish products are a good source of minerals. Mineral elements detected were in the decreasing order of Ca>Mg>Fe>Zn>Mn>Cu in fresh processed five types of shol, taki and tengra fish-products respectively. xxvii During storage period, protein, fat, ash, salt and sensory score were found to be decreased whereas moisture, TVB-N, FFA, pH, SPC and HBC value increased both room and refrigeration temperature, but the increase in room temperature was more prominent than the products stored in refrigeration temperature. However, there was a general decline in sensory characteristics and scores on flavor, color and texture of salted fish-products during storage (a total period of 36 months) and the acceptability score <4.5 (in 1-9 point hedonic score on quality) was considered as rejected or spoiled for all salted fish samples. There was also found direct relation between moisture & chemical composition (TVB-N, FFA, pH) and moisture & bacterial count (SPC, HBC) whereas inverse relation was revealed between sensory score & TVB-N, FFA, pH value during entire storage period. Visually there was found no fungal attack in all of 5 types of salted shol, taki and tengra fish products during the storage period. The overall quality of all salted fish-products were excellent in fresh process condition and five types of salted products stored at refrigeration temperature were found in better condition as determined by sensory, biochemical and bacteriological analysis. From the overall performance, it has been proved that these three fishes were highly acceptable in salted condition and turmeric treated sun-dried salting (SDS+T) method was found as the best. On the basis of quality-standard and shelf-life performance, the five salting methods can be arranged as follows: Turmeric treated sun dried salting (SDS+T)>Sun-dried salting (SDS)>Dry salting (DS)>Pickle curing (PC)>Brine salting (BS). Among the three species, five categories of salted tengra fish-samples showed better performance in respects of shelf life study. The highest shelf life was found to be 36 months in SDS+T tengra at refrigeration storage whereas lowest was found in 75 days in BS taki at room temperature. Thus the present study provides information about the suitability of different salting methods of three commercially important fishes to produce a very stable and safe product with long storage life. By assessing the nutritional quality as well as the feasibility of the method, it can be recommended to incorporate the turmeric treated sun-dried salting (SDS+T) method in commercial scale which further may contribute in national economy of Bangladesh.
Relationship between phenological stages of boro rice and the stages of life cycle of yellow rice stem borer (Scirpophaga incertulas) in fields
(University of Dhaka, 2018-09-06) Moula, Golam
An experiment was carried out to evaluate the “Relationship between phenological stages of boro rice and the stages of life cycle of yellow rice stem borer (Scirpophaga incertulas) in fields” at the experimental stations of Porabari, Salna, Gazipur, adjacencent to Bangabandu Sheikh Mujibur Rahman Agricultural University, Gazipur and different laborites of Bangabandu Sheikh Mujibur Rahman Agricultural University and Environmental Biology and Biodiversity Laboratory (EBBL), Department of Zoology, University of Dhaka, during the boro season, November, 2010 to May, 2014. The results revealed that the plant height, number of total tillers, number of effective tillers, LAI, CGR, NAR and RGR significantly varied among the varieties at different phenological stages as well as the duration of different phenological stages differed significantly among the varieties. From the biological study of yellow rice stem borer (YSB), it was found that the duration of egg to larva, larva to pupa, pupa to adult and total life cycle of YSB were 6. ±0.5 days, 28.2 ± 0.60 days, 8.1± 0.44 days and 42.3±1.25 days respectively. From the coincidence of phenological stages of rice varieties and the stages of life cycle of YSB, it was observed that the adult YSB always appeared maximum and laid eggs at vegetative stage at the 4th week of February and eggs changed into larvae at the same phenological stage, larva changed into pupa at reproductive stage and pupa changed into adult at post reproductive stage of all rice varieties. After harvesting the rice varieties, the newly emerged adult eggs remained in the stubble of paddy fields. This coincidence of two biotic aspects (rice varieties and YSB) continued among the distinct phenological stage of rice and the specific life stage of YSB (S.incertulas ) in three different rice growing seasons (aus, aman and boro) in Bangladesh throughout the year . Mid-January transplanting time of rice varieties in boro season might be made a temporal favorable coincidence between the each life stages of YSB and the different phenological stages of rice varieties. From the nature of damage, it was found that the infested hills as well as infested tillers were maximum at preflowerng stage and minimum were in active tillering stage in all varieties. Considering the prevalence of appearing of optimum phenological stage of rice and the adult YSB arrival time, percentage of infestation as well as rice yield, the best time for transplanting rice seedling in boro season would be early or late January instead of mid- January. Moreover, the stubble ploughing and flooding the paddy fields after immediate harvesting reduced the percentage of infestation of YSB.
Occurrence of communicable diseases and their risk factors among the female inhabitants of lower socioeconomic groups in Dhaka city
(University of Dhaka, 2018-12-05) Karim, Mt. Tahmina
Identification of the type of most common communicable diseases and prevalence of each disease was observed among the female inhabitants of lower socioeconomic groups in Dhaka city. A total of 900 female inhabitants were examined during Sep 2013 to Aug 2015, prevalence of gastrointestinal parasitic infestation was 66.22% and 26 parasite species were identified. Prevalence of nematoda was the highest (57.55%), then cestode (38.67%), protozoa (19.22%) and lowest was found in trematode (4.11%). Entamoeba histolytica (10.44%) indicates severe faecal contamination among protozoan parasites, while in cestodes Hymenolopis nana (22.78%), in trematodes Fasciolopsis buski (2.11%) and in nematodes Ascaris lumbricoides (38%) were highly prevalent. In twelve study areas, the highest prevalence was found in Kamrangichar (87.5%). The peak prevalence (82.5%) of infection was observed in rainy season. Double and triple parasitic infection was higher than that of single infection. Children of age group 1-15 years (75.65%) were mostly affected by intestinal parasite. The overall prevalence of anaemia was 42.22%. Anaemia was significantly higher (49.6%) in 16-30 years of adult group and severe anaemic cases also found within the same age group. Comparatively higher percentage was found in anaemic and parasite positive cases (70.53%) than non anaemic parasite positive cases (63.08%) that prove that parasitic infestation is one of the main reasons for anaemia. The prevalence of Urinary tract infection was 31.44% and the highest prevalence of urinary tract infection was observed among adult age group (46.8%). Therefore, female from adult age group were vulnerable to many diseases. Comparatively higher UTIs cases were found in rainy seasons (40.31%). The percentage of E. coli was found highest (65.72%) for causing UTIs. Among 900 female inhabitants, 41.33% were infected with different types of skin diseases; within these, bacteria (45.16%), fungal (26.07%), viral (19.35%) and arthropod (9.41%) infections were found. Among them, the highest 54.28% were infected by scabies and 38.09% were affected by boil disease. The highest prevalence of skin diseases was observed among the adult age group. The prevalence of vector-borne diseases was 49.33%, among them four types of diseases were recorded which are malaria (2%), filaria (7.33%), dengue (34.67%) and leishmaniasis (5.33%). Dengue (64.25%) and malaria (4.66%) infection was found highest among the children while filaria (12.18%) and leishmaniasis (8.12%) found in middle age group. Four types of waterborne diseases were found such as cholera/ diarrhoea (28%), typhoid (17.11%), polio (5.11%) and hepatitis A/ Jaundice (9.67%); and overall prevalence was 59.87%. Regarding the airborne diseases, 58.44% were found to be infected, among them four types recorded, such as influenza (25.11%), mumps (10.22%), pneumonia (17.44%) and tuberculosis (5.67%). The major proportion of the waterborne infections (71.50%) and airborne infections (69.43%) were found in children group. The main source of disease transmission may be associated with socioeconomic condition, sanitation and personal hygiene, so these sources were considered to be risk factors. Risk factors and socioeconomic aspects of the female inhabitants in relation to parasitic, skin, vector-borne, waterborne and airborne diseases were also calculated.
Cyanobacteria bloom dynamics in eutrophic ponds and their toxic effects on Oreochromis niloticus and Hypophthalmichthys molitrix
(University of Dhaka, 2018-12-06) Ahmed, Sumaiya
Cyanobacteria are the most ancient form of life and create harmful algal blooms in freshwater, estuarine and marine ecosystems. It produces some secondary metabolites known as cyanotoxins which pose threat to humans, animals and the environment. Cyanobacterial blooms are common phenomenon in freshwater eutrophic ponds and lakes in Bangladesh. A study was conducted to assess the plankton diversity especially the cyanobacteria and their bloom in four eutrophic ponds in Mymensingh Sadar Upazila and their relationship with physicochemical parameters in both spatial and temporal scales. Plankton samples were collected along with water quality parameters from January 2012 to December 2013. A total of 22 plankton genera of six families were identified. Among them, Ceratiacea (81.36%), Cyanophyceae (72.74%), Euglenophyceae (47.23%), Peridiniaceae (28.67%) found highest in number in Pond 1 (P1), Pond 3 (P3), Pond 4 (P4) and Pond 2 (P2), respectively. Species composition of phytoplankton was typical of eutrophic conditions (high PO4-P, N03-N and NH4) was frequently characterized by the presence of Cyanobacterial bloom but it was also found in scarcity of nitrogen (Microcystis aeruginosa, 30,000 colony/L, June 2013, P3). Plankton diversity status was analyzed by using PAST (Paleontological Statistics version 2.17) software. Result showed that Microcystis sp., Ceratium sp., Tracheolomonas sp., Lepocinclis sp., and Spirulina sp. were the major contributing species (17%) for season all basis. Analysis of Similarity (ANOSIM) results showed that spatial differences and low temporal similarity in species community structure with a diverse assemblage. Canonical Correspondence Analysis (CCA) has been carried out to show the relationship among spatial and temporal data. With the CCA analysis, Conductivity, Ammonium, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Nitrate Nitrogen had positive correlation with several phytoplankton species Cyanophyceae (Microcystis sp., Spirulina sp., Lepocinclis sp., Merismopodium sp., Anabaenopsis sp.) and Cholorophyceae (Senedesmus sp., Phacus sp., Pandorina sp.). A bloom of Microcystis aeruginosa was occurred in P3 in May 2013. Bloom sample was collected and analyzed with High performance liquid chromatography (HPLC). Five types microcystins (MC) were detected. The concentration of MC-RR was the highest (5.4μg/L) followed by MC-YR (1.14 μg/L), MC-WR (0.46 μg/L), dm-MC-RR (0.36 μg/L) and MC-LR (2.0 μg/L) which was much higher than the WHO provisional guide value (MC-LR 1 μg/l) for drinking water. Another Microcystis aeruginosa bloom sample was collected from P4 during June 2013. Two types microcystins were detected and the highest concentration was MC-RR (1.0 μg/l) followed by and dm-MC-RR (0.04 μg/l). Among the organs tested of fish (Oreochromis niloticus) sample MCs were only detected from the liver and the concentration was MC-RR (0.049 μg/gm) which was much higher than provisional guideline of WHO 0.04 μg/kg TDI (tolerance daily intake). No MCs was detected from the gut and muscle of the fish (Oreochromis niloticus). Histopathological study confirmed the damage of liver cell of fish exposed with Microcystis aeruginosa bloom in vitro experiment. In exposed fish (Oreochromis niloticus), histopathological alternations were characterized by swollen and granular cytoplasm, vascular proliferation, bile stasis, fatty change and focal necrosis. The present study thus suggested that fish farms should be monitored for the presence of toxic cyanobacterial blooms to minimize the exposure of potent hepatotoxins to fish and humans through the food chain. So, sustained integrated monitoring system for aquaculture and domestic ponds is strongly recommended.
Genetic diversity among different species of hilsa shad (Clupeidae) of three major aquatic environments in Bangladesh
(University of Dhaka, 2018-12-09) Rahman, Md. Sharifur
DNA barcoding has been adopted as a global bio-identification system for animals in recent years. DNA barcoding, based on the sequencing of a standardized region of the Cytochrome C Oxidase subunit I (COI) gene, has received considerable attention as an accurate and broadly applicable tool for animal species identification. Mitochondrial DNA (mtDNA) has been used extensively in the last three decades as a tool for inferring in the evolutionary and demographic past of both populations and species. This tool has proven invaluable for the new field of molecular ecology and phylogeography. Hilsa shad (Bangali name: Ilish or Elish) is the largest single fishable species in Bangladesh, present in almost all the major river systems, estuaries and Bay of Bengal. Genetic diversity of Tenualosa ilisha, T. toil and Hilsa kelee in Bangladesh were studied from August 2012 to December 2016. Samples were identified based on its morphological characters. In this study, 650 base-pair region of the COI gene was sequenced from samples collected from different regions. The BLAST analysis confirms the three species. The result from BLAST showed that the sequences have high similarity with the existing COI gene sequences of NCBI GenBank. Sequence alignment of all Hilsa and Tenualosa individuals revealed highly consistent 99% - 100% similarity among the species. High efficiency of species identification was demonstrated in the present study by DNA barcoding. In addition to barcode-based species identification system, a phylogenetic analysis was done using Maximum Parsimony (MP) and Maximum Likelihood (ML) methods. The results showed an identical tree topology with minor differences in bootstrap confidence levels. The evolutionary distances indicated that the mean interspecies distance was 25.52%, while the intraspecies distance was 0.22%. Therefore, the study indicates that there are three sepcies of hilsa, and COI is an ideal genetic marker that can be used to identify and confirm the nature of these species. Further studies can be done with large number of samples in wide geographic regions to deeply understand the population structures of these species.
Onset of migration and bioenergetics of selected fishes of Bangladesh
(University of Dhaka, 2018-12-23) Zaman, Maria
The damming of rivers and canal has been a major contributor to the decline of fish migration and population in Bangladesh. Fish are confronted to a challenging hydrodynamic environment when they swim upstream. Nevertheless, the knowledge of fish behaviour in these conditions is limited, particularly for coarse species such as cyprinids. The principle focus of the study is to evaluate fish swimming behaviour in different hydrological condition, onset of migration, fish migratory behavior, swimming speed and survival in different of water velocity condition. In situ experiment in Sariakandi shows fish fry, hatching, juvenile and adult movement from Jamuna to Bangaliriver. After construction of the fish pass, the diversity of fish species of the Bengali River is increased. Ex situ experiments have been conducted in an indoor full scale vertical slot fish pass model with different sizes (fry, fingerling, juvenile and sub-adult) of cyprinid species Rui (Labeorohita), Catla (Catlacatla) and Mrigal (Cirrhinusreba) as well as some other test fishes. Different water velocity used to study fish cruising, sustained and burst swimming activity, indicating some degree of anaerobiosis occurs during crossing passage. Energy used by individual fish to pass the fish friendly structure varied greatly due to different migration behavior, passage routes, and the time it takes to pass related to water current. Mortality risk to the migrant is estimated. Results identified areas of difficulties in a fish passage that may be modified to help decrease energy use of upstream migrating fishes. The results emphasize the value of achieving a deeper understanding of fish requirements in these devices and show the potential of the methodology developed to fulfil this objective. Results can contribute to develop robust guidelines for future fishway designs in Bangladesh.
Some epidemiological aspects of lymphatic filariasis and its prevention by using some fish predators
(University of Dhaka, 2019-05-07) Rafiqul Islam, Akond Mohammad
The present study was carried out mainly in the two extreme poor prone zones like north and south zones of the country consisting 20 districts, among those, three districts like Gaibandha, Sylhet, Mymensingh are non-endemic area of filariasis. It was observed that, the factors which make the reduction of prevalence of lymphatic filariasisare the cost effective safe way control of the vector of lymphatic filariasis and also the effectiveness of predation by fish as a control measure of the vector of lymphatic filariasis. The availability and suitability for surviving the mosquito larvae and their predators in the same water bodies surrounding the lymphatic filariasis affected patient’s house was also recorded. On the basis of the above mentioned factors, different aspects of Lymphatic filariasis in Bangladesh including its epidemiological aspects, knowledge attitude and practices of the people and the scope of its prevention by using some fish predators were studied in the present study. Out of 20 studied districts, Bagerhat, Gopalganj, Sylhet, Narail, Mymensingh and Norshindhi have no patients of filariasis. The highest frequency of patients found in Lalmonirhat educational status/knowledge/awareness of the household’s people. Very few patients of endemic district are used to go for treatment to the health complex. Mosquito larvae and their predators were collected from three different types of habitat from the study areas. Ditch and abandoned ponds are abundant in south zone but the pit surrounding the tube well is the main breeding grounds in north zone, so the more effective breeding grounds for the vector of filariasis like-Culex quinquefasciatus is higher in north zone than that of south zone. Pit surrounding the tube well Fishes collected from mosquito breeding grounds were allowed to feed upon different instars of Culex quinquefasciatus to determine their predation capacity. Among the fishes Clarias batrachus consumed the highest number of larvae It may be concluded that filariasis is mainly poor people disease because of their illiteracy and unhygienic-unhealthy living of standard. The lack of awareness, poor water-sanitation condition and living place surrounded by the mosquito breeding grounds are also responsible for endemism. The prevention mechanism of this disease should be predation of larvae by fish predators which will be safe for health and cost effective. So the study findings suggest for culturing suitable fish in the breeding grounds of mosquito larvae as a preventive measure against filariasis. Though the filariasis is a poor people disease, so poverty alleviation program should be expanded in every pocket of poverty stricken area. Poverty alleviation program for the poorest of the poor not only for upgrading their economic condition but also for upgrading their socio-cultural condition; increasing community participation in infrastructural condition;increasing awareness; changing attitude; providing health knowledge towards the causes, preventions and safe way control measures of filarial disease.
Incidence and detection of Blastocystishominisamong the infants in Dhaka
(University of Dhaka, 2019-05-20) Faruqui, Rifat
In the present study, three techniques: Direct microscopy, in vitro culture and PCR methods were applied to detect Blastocystis hominis. Multiple stool samples of 406 children were collected from Mirpur, Dhaka and 118 children from Mohammadpur slum area, Dhaka. The whole work was done in the Parasitology Laboratory, icddr,b, Mohakhali, Dhaka-1212. During the study period (from January 2012 to December 2013), in Mirpur area, out of 9322 stool samples, 8601 samples were observed on monthly basis called Monthly Stool (MS) samples and remaining 721 samples were Diarrheal Stool (DS) samples. In Mohammadpur area, out of 3218 stool samples, 2704 samples were MS samples and remaining 514 samples were DS samples. By microscopy, the prevalence of B. hominis in MS and DS samples were 3.72% and 5.83% in Mirpur area and 7.25% and 9.73% in Mohammadpur area respectively. According to culture examination, the prevalence of B. hominis in MS and DS samples were 34.25% and 27.32% in Mirpur area and 42.60% and 40.47% in Mohammadpur area respectively. It was observed that prevalence found higher by in vitro culture method than direct microscopy in all types of samples of both areas. According to age groups of children, it was observed that prevalence was higher among 37-48 and 49-60 months age groups in MS and DS samples of both areas. Statistical analysis exhibited that there was no significant relationship between sexes in children for B. hominis infection. It was observed that female were more infected, by microscopy (4.16%) and by in vitro culture (35.07%) collected from Mirpur area. While, by in vitro culture method, female was more prevalent (42.79%) than male (41.59%) in overall samples from Mohammadpur area. By the analysis of variance it was revealed that there was a significant association between age groups of children for B. hominis infection. Four morphological forms of B. hominis: cyst, vacuolar, amoeboid and granular, which were clearly distinguished by in vitro culture method. Prevalence of cyst, vacuolar, amoeboid and granular forms were 31.09%, 13.63%, 11.50% and 5.88% respectively in stool samples of Mirpur area, while comparatively higher prevalence 38.66%, 29.58%, 18.09% and 2.89% were observed respectively in stool samples of Mohammadpur area. To observe seasonal variation, by microscopy and in vitro culture method, in MS and DS samples of both areas, prevalence of B. hominis were higher both in summer and rainy seasons than winter. The seasonal variation (F-test), were significant (P=0.05* and p=0.000**) in DS samples of Mirpur and Mahammadpur areas. Monthly incidence of B. hominis in stool samples of study areas showed positive correlation with climatic factors (temperature, humidity and rainfall). It was observed that in DS samples of both areas, incidence were significantly correlated with temperature (p=0.004** and p=0.000**) and rainfall (p=0.004** and p=0.001**). The prevalence of B. hominis by direct microscopy was 4.50%, by in vitro culture method was 29.86% while by Real-time PCR method was 42.42% respectively in stool samples of Mirpur area, while these were 9.44%, 39.44% and 53.33% respectively in samples of Mohammadpur area. Comparisons among three methods, showed that the mean difference were highly significant (p=0.013** and p=0.000*) in stool samples of both areas. The main goal of the present investigation was to prove the perfect technique for maximum detection of B. hominis. As a result the Real-time PCR is the gold standard as it showed highest sensitivity than direct microscopy and in vitro culture method.