Thesis (M. Phil.)--University of Hong Kong, 2004. / Title from PDF t.p. (viewed on Dec. 19, 2005). Includes bibliographical references (leaves 248-266). Also issued as print manuscript.

Thesis (M. Phil.)--University of Hong Kong, 1986.

Morphological and histological studies of imposex has been studied in the oyster drills, Thais clavigera and T. rufotincta. The sex ratios of the collected samples were close to 1:1 among sites of Shunsun, Taishi, Budai, Chiku and Donkang. The relative penis sizes (RPS values) of T. clavigera were higher than T. rufotincta, indicating a high imposex degree in T. clavigera. The RPS values of T. clavigera showed seasonal variations, because the penis length of males and females were longer in the reproductive season, but the trends were inconsistent among the sampling sites. The RPS values in Shunsun and Taishi were higher in March (reproductive season) and lower in August (non-reproductive season), but Budai and Chiku were in a contrary way. It is suggested that the inconsistent patterns may result from temporal and spacial variations of tributyltin (TBT) and triphenyltin (TPT) concentrations among sites. For imposex females, they all developed penis and vas deferens. In the heaviest affected female T. clavigera, aborted egg capsules within the capsule gland that renders the female sterile has been observed. The percentage of capsule gland blockage in Shunsun, Taishi, Budai and Chiku were 7.7%, 9.7%, 50% and 0%, respectively. Other accessory sex organs, i.e. the lengths of capsule gland and prostate glands were all longer in reproductive season, and the difference among sampling sites were also significant. In histological studies of T. clavigera and T. rufotincta, the male testis tissue from all sampling sites contained all developing stages sperm cells in March; as females from March, the ovary tissues were full with mature oocytes. However, in Shunsun and Budai, there were many hemocytes found in the ovary tissues of T. clavigera that might result from imposex. In lab-experiments, T. clavigera were treated with TBT and TPT for 44 days, there was no difference in female penis length between control and TBT or TPT treated groups. The ovary and testis tissues were all developed normally. In general, there is no obvious abnormality in imposexd T. rufotincta. On the contrary, in T. clavigera, the female opening (vulva) occluded by overgrowing vas deferens which might prevent the spawning of egg capsules. In addition, some hemocytes were found in the ovary tissues in T. clavigera and the phenomenon of sex change was not observed. Meanwhile, no obvious abnormality was observed in the testis tissues of T. clavigera.

Oyster drills are common on rocky shores and oyster (Crassostrea gigas) farming areas in Taiwan. Most studies on the oyster drill (Thais clavigera) were on its impact on the oyster industry. However, there are at least three Thais species in the west coast of Taiwan. And the basic biology of T. rufotincta and T. keluo was insufficient. Thus, the present study was undertaken to investigate population biology of the three congeneric drills(Thais spp.), including feeding rate, reproductive characters and population dynamics. T. clavigera was distributed from Tamsui to Tongkong along the west coast of Taiwan. But, it was rare at Tongkong. T. keluo was primarily found at Tamsui and Tongkong. The distribution of T. rufotincta was from Tongkong to Tamsui and mostly occurred between Tongkong and Taishi. Mean feeding rates (¡ÓSE) of T. clavigera, T. keluo and T. rufotincta were 0.054(¡Ó0.010), 0.038(¡Ó0.004) and 0.010(¡Ó0.003) oysters/snail¡Eday, respectively. The feeding rate of T. rufotincta was significantly lower than other species (P<0.05). It is suggested that the major damage on oyster culture is caused by T. clavigera and T. keluo. The spawning seasons of T. clavigera, T. keluo and T. rufotincta were from November to May, from February to September, and from April to October, respectively. The number of eggs per capsule was correlated with the length of the capsule (P<0.001) in T. clavigera, T. keluo and T. rufotincta and the number of eggs (¡Ó 95% C.I.) among them was 203(¡Ó14), 168(¡Ó15) and 43(¡Ó3) per capsule, respectively. The mean egg diameter (¡Ó 95% C.I.) of the three drills was 185(¡Ó3), 175(¡Ó4) and 240(¡Ó6) £gm, respectively. Positive curve relationships between size and weight were found among Thais spp. (P<0.001). Using the length-frequency data, analyzed by the ELEFAN (Electronic Length Frequency Analysis) program, the seasonalized von Bertalanffy growth parameters for Thais spp. were estimated. The growth performance index (&#x00F8;') and growth parameter (K) showed a similar trend, i.e. Chiku>Tamsui>Shiangsan for T. clavigera, Tamsui > Tongkong for T. keluo, and Chiku > Tongkong for T. rufotincta. It is suggested that water temperature and food abundance are important factors affecting drills¡¦ growth in the west coast of Taiwan. The recruitment of T. rufotincta at Chiku and Tongkong had two peaks. It was different from T. clavigera and T. keluo with only one peak. Futher studies are necessary to elucidate the relationship between recruitment with different peak periods among sites and environment variables such as primary production, salinity, current and so on.

published_or_final_version / Zoology / Master / Master of Philosophy

Previous studies in the population genetics of the oyster drill Thais clavigera show that snails from the west coast of Taiwan belong to the same population. However, the genotype frequency of arginine kinase (Ark) in large snails is different among sites in the west coast. In general, changes of temperature and desiccation caused by tidal cycle are the most important twp environmental factors affect genetic variation of intertidal organisms. In the present study, the relationship between the frequency of Ark genotype and tide was evaluated through the following experiments. It has been found that the frequencies of Ark genotype of snails, collected in August with the size range of 25-35mm, were correlated to tides. A higher grequency of Ark63/100 (0.47~0.56) was in the upper intertidal and a higher frequency of Ark63/63 (0.49~0.66) was at the lower end. Moreover, the genotype frequency also varied with size, i.e. more Ark63/63 in small snails (<25mm) and more Ark63/100 in large snails (>35mm). Laboratory desiccative experiments indicated that snails with genotype of Ark63/100 preferred in the areas of high water level and Ark63/63 in areas of low water level. The laboratory results were consistent with the field data. To compare the enzyme activity, there was no difference among the genotypes of Ark63/63, Ark63/100 and Ark100/100at temperatures of 18, 24 and 30¢J. In summary, the frequencies of Ark genotype varied with tide and size and factors such as temperature, desiccation and reproduction may play important roles in the relationship.

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 223-242).

Ethnic minorities in Hong Kong are usually ignored. However, their participation and contribution in the Hong Kong history are not negligible. There are a group of Thai settled in Kowloon City for decades. And because of their existence, Kowloon City is known as the “Little Thailand” in Hong Kong. By understanding this group of people through their history and development, one can recognize that they are very special to Hong Kong. With the removal of the Kai Tak International Airport, Kowloon City is now under re-development pressure. The Thai, which has been settling in the area since 1970s, may face the risk of losing their living places. It can be seen that some Thai stores and restaurants have already been closed or moved to other areas due to the increasing shop rents over these few years. It is crucial to record their significances in Kowloon City before this unique culture vanishes. Kowloon City is an area with a very characteristic historical background and setting. The area is famous of its dense streets forming a fish-bone shape, with Nga Tsin Wai Road as the main street which connects all other streets together. Kowloon City is a place for different styles of food. There are oven 200 restaurants which many of them are in Thai style. As a result, Kowloon City is also called “Little Thailand”. Thai is one of the ethnic minority groups in Hong Kong. The 2011 Hong Kong by-census report showed that about 14,000 Thais living in Hong Kong, making up around 2.9% of the total non-Chinese population, and about 0.2% of the total Hong Kong population. Most of them live on the Kowloon side, with the majority in Kowloon City and Kwun Tong1.Many Thais live and own restaurants and stores in Kowloon City. Due to the Kai Tak Airport nearby, the height of buildings in Kowloon City is limited. With the demolishment of Kai Tak Airport, the area is under re-development pressure. Developers start to purchase old buildings for high rise modern buildings and the rents of shops significantly increase over these years. The Thais who used to base around the area are under threat of moving to other areas, and the characteristic of “Little Thailand” may start to vanish. The objective of this dissertation is to understand the Thai community in Kowloon City, document their activities, identify their character-defining elements and values and study their potential challenges. The study area is focused on South Wall Road, which has a high density for Thai-related businesses and activities. This dissertation aims to study the tangible and intangible character-defining cultural heritage elements of the Thai community at Kowloon City. To achieve this research goal, it is essential to understand the place and the community’s origins, history and culture. However, given the limited time, it is not possible to carry out a comprehensive research of the Thai community in the entire Kowloon City. Instead, the research must limit its scope by focusing on a small but representative study area within Kowloon City. The purpose of this is more about demonstrating the research process through a smaller study area so as to set a “template” for future research that extends to other study areas at Kowloon City. This dissertation adopts the research methodology of cultural mapping for documenting the tangible and intangible assets of the area in order to better understand the place and its culture, and focuses on the area with more Thai-related activities in Kowloon City. South Wall Road, which is chosen as the study area, is one of the major streets for Thai activities including shops and restaurants, and festivals. By conducting field studies and interviews, the lives of the Thai and their unique cultures can be recorded and understood. --------------- ------------------------------------------------------------ --------------- ------------------------------------------------------------ / published_or_final_version / Conservation / Master / Master of Science in Conservation

Thesis (Ph. D.)--University of Adelaide, 1991. / Includes bibliographical references (leaves 419-451).

Thesis (Ph. D.)--University of Adelaide, 1991. / Bibliography: leaves 419-451. Also available via World Wide Web.