香港瓮缸群岛野生植物资源调查研究

香港瓮缸群岛共有维管植物166种,隶属于69个科138个属,其中蕨类植物7科8属10种,裸子植物2科2属2种,被子植物60科128属154种。瓮缸群岛为香港著名离岛,植被生境无人为干扰,野生植物资源利用度较低,本文通过对瓮缸群岛的植被类型和野生植物资源进行统计分析,结果表明,该群岛可供利用的植物资源共10类,分别为：药用植物103种、观赏植物107种、食用植物21种、牧草及饲用植物23种、材用植物17种、油脂植物22种、芳香精油植物25种、纤维植物13种、鞣料植物11种、有毒植物26种等,都有很高的开发利用潜力,在此基础上提出相应的保育及开发利用建议,旨在更好地保护和合理利用该群岛的野生植物资源。     

Mycorrhizal associations in Hong Kong Fagaceae

A rapid method of screening has been devised whereby the large seeds (acorns) of Castanopsis, Lithocarpus and Quercus growing in Hong Kong can be germinated in the presence of a variety of known mycorrhizal fungi and observations made on the initiation of host/fungal associations. Early stages of Hartig net formation could be detected in bleached roots, and an observation was made on the antibiotic activity of the mycorrhizal fungus, Pisolithus tinctorius. The method offers a simple and effective means of assessing the potential of fungi to form mycorrhizal associations under non-sterile conditions.     

Conservation evaluation of nine Hong Kong mangals

A comparative analysis of the conservation value of nine Hong Kong mangals spread across Hong Kong has been undertaken. The analysis is based on both biological and socio-economic attributes. Biological attributes used in the analysis include plant species richness, benthic and arboreal gastropod species richness, occurrence of rare species within each site, and site representativeness. A review of the past and present development and development plans around and within each site has been undertaken to assess the comparative degree of hazard to each mangal. The drastic decline of mangal habitats throughout Hong Kong highlights the need for conservation of what remains today. Priorities and strategies for conservation of these nine mangals are discussed with particular emphasis on the preservation of biodiversity and the management of these habitats as education and research sites.Department of Applied Biology & Chemical Technology, Hong Kong Polytechnic     

The distribution of mangrove-associated gastropod snails in Hong Kong

The distributions of mangal gastropod snails in Hong Kong were investigated by transect studies in nine mangals from around the coast. Fifty-one species of mangal associated were found, of which 25 were considered common. Gastropod faunas varied considerably between sites, both in terms of number of species and species composition. No one gastropod assemblage was found to be typical of the Hong Kong mangal. Local habitat differences were considered to have a major influence over species distributions, both within and between mangals. It is concluded that if species diversity is to be preserved then a representative sample of mangals needs protection.     

香港次生林下植物菌根的调查

本文报道了香港６４种野生植物根系天然感染菌根菌的状况：９８．４％的植物都不同程度地感染上了菌根菌,９８．１％的根样发现受内生菌根（ＶＡＭ）的感染,其中小叶青冈（Ｑｕｅｒｃｕｓｍｙｒｓｉｎａｅｆｏｌｉａ）同时受外生菌根（ＥＣＭ）和内生菌根的感染。该研究揭示了香港次生林植物在自然条件下受菌根菌感染的普遍性,为进一步探讨华南地区菌根与退化地区植物群落演替的关系提供了重要的本底资料。     

Factors affecting the distribution of lignicolous marine fungi in Hong Kong

An investigation into the effect of environmental factors on the general distribution and occurrence of lignicolous marine fungi using submerged blocks of pine (Pinus massoniana Lamb.) and teak (Tectona grandis L.) was carried out for 18 months in the coastal waters of Hong Kong. Five test sites, with environmental conditions varying from estuarine to oceanic, and from polluted to non-polluted, were selected. During each collection, salinity, temperature, pH, dissolved oxygen, biochemical oxygen demand, nitrate-nitrogen, inorganic phosphate-phosphorus and light transmission were measured. A total of 51 species of fungi were recorded among which only 28 were either obligate or facultative marine forms. Neither the general distribution pattern nor the distribution of the more frequent fungi could be solely accounted for by differences in salinity at the test sites and it is suggested that other ecological factors such as heavy sediments in the waters, low pH, and the presence of an abundant source of inocula may be important.     

A population-based study of Helicobacter pylori infection in Chinese children resident in Hong Kong: prevalence and potential risk factors

Background: Data of Helicobacter pylori prevalence in children and its risk factors provide clues to the health authority to estimate burden of H. pylori‐associated diseases usually encountered in adulthood and facilitate healthcare planning. Materials and Methods: A cross‐sectional population‐based study was conducted in Chinese children in elementary and high schools. Schools were selected from all three major areas of Hong Kong. H. pylori infection was defined by a positive ¹³C‐urea breath test. Study subjects were stratified into six age groups for estimation of prevalence. Potential risk factors were analyzed from data of self‐administered questionnaires. Results: A total of 2480 children (aged 6–19, male: 47.3%) participated in the study. Overall, 324 (13.1%) were positive for H. pylori. There was no difference in prevalence between sexes, and no statistical trend in the prevalence across the six age groups. Multivariate logistic regression identified lack of formal education of mother (OR = 2.43, 95%CI 1.36–4.34), family history of gastric cancer (OR = 2.19, 95%CI 1.09–4.41), and household member > 5 (OR = 1.57, 95%CI 1.12–2.19) to be positively associated with H. pylori infection in our children. Conclusions: The H. pylori prevalence of Hong Kong children is comparable to the data of developed countries. The association with family history of gastric cancer justifies further study to investigate the cost‐benefit of community screening program for such children to decrease the incidence of gastric cancer in adulthood.     

Spawning periodicity of three species of Nodilittorina in Hong Kong

The spawning periodicity of Nodilittorina trochoides, N. radiata and N. vidua from two rocky shores of different wave exposure, Big Wave Bay (more exposed site) and Cape d'Aguilar, in Hong Kong was monitored for one year (November 1994–November 1995). The breeding season was similar for the three species, mainly during the summer (June–September). The spawning duration was 9 months for N. vidua and 7 months for the other two littorinids. Spawning was initiated at different times for the two sites. At Big Wave Bay, spawning occurred between May–November for N. trochoides; March–September for N. radiata and March–November for N. vidua. At Cape d'Aguilar, the spawning period of N. trochoides and N. radiata was similar (April–October), whilst for N. vidua, spawning extended up to December. A decrease in monthly fecundity was recorded during July and August at Big Wave Bay and Cape d'Aguilar respectively. A weak relationship was found between the size of reproductive females and egg production. The seasonal fecundity of N. trochoides and N. vidua was similar at both sites and estimated as 10 000 and 7500 eggs per female respectively. Fecundity of N. radiata varied between sites, with 15 000 eggs and 9000 eggs per female being recorded from Cape d'Aguilar and Big Wave Bay respectively.     

Mapping and characterization of mangrove plant communities in Hong Kong

Ecological surveys were carried out to investigate the distribution and characterization of remaining mangrove stands in Hong Kong. The field studies indicate that 43 mangrove stands, excluding Mai Po Nature Reserve, still remained along the coastline of Hong Kong despite tremendous reclamation and development which occurred in the past 40 years. Most mangrove stands were found in Deep Bay (western part)and Sai Kung District (eastern coasts). The total areas occupied by these mangrove stands were 178 ha,varying from a very small stand (with 1–2 mangrove shrubs) to fairly extensive mangroves in Deep Bay (> 10 ha). It appeared that mangrove stands located in Deep Bay area were larger than those in the eastern coasts. Twenty plant species were identified from these stands, with 13 being exclusive or associate mangrove species. The major constituent species were Kandelia candel, Aegiceras corniculatum, Excoecaria agallocha and Avicennia marina. Rare species such as Heritiera littoralis were only found in a few mangrove stands. Out of the 43remaining mangrove stands, 23 were more worthwhile for conservation and their plant community structures were further investigated by transect and quadrat analyses. The importance values (sum of relative abundance,frequency and dominance) show that K. candel was the most dominant species. Species richness and Simpson's indices together with tree height, tree density and canopy area fluctuated significantly between mangrove stands. These values were used to prioritize the conservation potential of the remaining mangrove stands in Hong Kong. This revised version was published online in August 2006 with corrections to the Cover Date.     

Comparative genomics of methicillin-resistant Staphylococcus aureus ST239: distinct geographical variants in Beijing and Hong Kong

Background

The ST239 lineage is a globally disseminated, multiply drug-resistant hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA). We performed whole-genome sequencing of representative HA-MRSA isolates of the ST239 lineage from bacteremic patients in hospitals in Hong Kong (HK) and Beijing (BJ) and compared them with three published complete genomes of ST239, namely T0131, TW20 and JKD6008. Orthologous gene group (OGG) analyses of the Hong Kong and Beijing cluster strains were also undertaken.

Results

Homology analysis, based on highest-percentage nucleotide identity, indicated that HK isolates were closely related to TW20, whereas BJ isolates were more closely related to T0131 from Tianjin. Phylogenetic analysis, incorporating a total of 30 isolates from different continents, revealed that strains from HK clustered with TW20 into the ‘Asian clade’, whereas BJ isolates and T0131 clustered closely with strains of the ‘Turkish clade’ from Eastern Europe. HK isolates contained the typical φSPβ-like prophage with the SasX gene similar to TW20. In contrast, BJ isolates contained a unique 15 kb PT1028-like prophage but lacked φSPβ-like and φSA1 prophages. Besides distinct mobile genetic elements (MGE) in the two clusters, OGG analyses and whole-genome alignment of these clusters highlighted differences in genes located in the core genome, including the identification of single nucleotide deletions in several genes, resulting in frameshift mutations and the subsequent predicted truncation of encoded proteins involved in metabolism and antimicrobial resistance.

Conclusions

Comparative genomics, based on de novo assembly and deep sequencing of HK and BJ strains, revealed different origins of the ST239 lineage in northern and southern China and identified differences between the two clades at single nucleotide polymorphism (SNP), core gene and MGE levels. The results suggest that ST239 strains isolated in Hong Kong since the 1990s belong to the Asian clade, present mainly in southern Asia, whereas those that emerged in northern China were of a distinct origin, reflecting the complexity of dissemination and the dynamic evolution of this ST239 lineage.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-529) contains supplementary material, which is available to authorized users.     

Nutrient flow in a major urban settlement: Hong Kong

A nutrient balance is established for the contemporary urban ecosystem of Hong Kong. The flow of nutrients in the Hong Kong food system in particular is examined, including current and potential nutrient recycling patterns. Losses of nutrients in food for human consumption are found to be up to 20% for major nutrients. The flow of mineral phosphorus in the Hong Kong food system is examined in detail. About 3600 tonnes of phosphorus are lost from the Hong Kong food system each year. A comparison is made between the land-based forage area demand of the Hong Kong population and a similar-sized Western population, that of Sydney, Australia. It is estimated that the average Hong Kong person consumes a diet which requires only half the land area needed to produce the diet of the average Sydney person. However, Hong Kong relies on the ocean for 25% of its animal protein supply compared with 2.5% for Sydney. Patterns of food production and nutrient recycling are proposed, with the aim of optimizing resource utilization in close association with contemporary urban settlements.     

Occurrence of fungi on submerged pine and teak blocks in Hong Kong coastal waters

An investigation of the lignicolous marine fungi in Hong Kong coastal waters was carried out for 18 months in order to determine successional patterns of fungal occurrence. Submerged blocks of pine (Pinus massoniana Lambert) and teak (Tectona grandis Linnaeus) were used as baits and were scraped at intervals to remove surface fouling organisms. Occurrence of fungi is described in terms of the composition of the fungal flora and the number of fungal colonies developed on the test blocks before and after incubation. The scraped teak and pine blocks supported slightly different fungal floras, and the selective effect of these substrates on fungal colonization is discussed.     

香港鸭嘴草＋野古草＋金茅群落的生物量和第一性生产力

香港鸭嘴草＋野古草＋金茅群落的生物量和第一性生产力管东生（中山大学环境科学系,广州５１０２７５）ＰｈｙｔｏｍａｓａｎｄＮｅｔＰｒｉｍａｒｙＰｒｏｄｕｃｔｉｖｉｔｙｏｆｔｈｅＧｒａｓｌａｎｄｉｎＨｏｎｇＫｏｎｇ．ＧｕａｎＤｏｎｇｓｈｅｎｇ（Ｄｅｐａｒ...     

Spatial distribution patterns of Littoraria species in Hong Kong mangroves

Variation in the abundance and distribution of two species of mangrove littorinid was investigated using a nested sampling design at different spatial scales, in the two dominant seasons, in Hong Kong. The abundance of Littoraria melanostoma, which was less abundant than L. ardouiniana, showed large-scale spatial variation whilst abundance of L. ardouiniana varied on both large and smaller spatial scales and interacted with seasons, indicating that the abundance of this species varied between mangroves in summer and winter. Small-scale variation suggested a patchy distribution of littorinids within a mangrove, whilst the large-scale variation might reflect changes in physical factors possibly associated with habitat fragmentation. Investigation of the vertical distribution of the littorinids on the mangrove trees revealed that L. melanostoma were located at a lower overall level than L. ardouiniana. This zonation pattern may be a result of the morphological differences of the two species, as L. melanostoma has a thick shell, whilst L. ardouiniana has a thinner, but colour polymorphic shell. Both species of mangrove littorinid showed patchy distributions at a variety of scales and these patterns highlight the importance of using a hierarchical sampling approach when investigating spatially fragmented habitats.     

A biological survey of ballast water in container ships entering Hong Kong

The role of ballast water in the introduction of exotic species has recently received extensive attention. The aim of this study is to assess the importance of ballast water discharge as a vector for the introduction of exotic species into Hong Kong waters. Twelve ballast water samples were collected from 5 container ships entering Hong Kong between June1994 and October 1995. The ballast water originated from ports on both sides of the Pacific Ocean. At least 81 species from 8 animal phyla and 5 protist phyla were found. Most of the major marine taxonomic groups were represented and many planktonic larval stages were included. Species richness in the ballast tanks decreased with the age of ballast water. Copepoda was the most diverse and abundant taxonomic group. The density of calanoid and cyclopoid copepods decreased with the age of ballast water, but that of harpacticoid copepods did not change significantly with time. Bivalve, crustacean, polychaete and ascidian larvae from ballast water samples were observed to settle in laboratory culture tanks. The mussel Mytilopsis sallei which was introduced to Hong Kong in 1980, was one of the bivalves that settled readily. Results of this study indicate that ballast water can be a major source for the introduction of exotic species to Hong Kong waters. Regulatory guidelines on the discharge of ballast water should be established. This revised version was published online in August 2006 with corrections to the Cover Date.     

香港大榄郊野公园的植物组成与植被数量分类

通过对香港大榄郊野公园森林群落的样地调查,利用组平均法和除趋势对应分析两种方法,对样方进行聚类与排序分析。把35个样地划分为11个植被类型,森林群落可划分为台湾相思（Acacia confusa Merr．）林、红胶木（Lophostemon confertus（R．Br．）PeterG．Wilson ex J．T．Waterh．）林、木荷（Schima superba Gardner ex Champ．）林、柠檬桉（Eucalyptus citriodora Hook．）林、湿地松＋鸭脚木（Pinus elliottii Engelm．＋Schefflera octophylla（Lour．）Harms．）林、土沉香（Aquilaria sinensis（Lour．）Spreng．）林、毛叶桉（Eucalyptus torelliana F．Muell．）林;灌木群落分为山油柑＋越南叶下珠（Acronychia pedunculata（L．）Miq．＋Phyllanthus cochmchinensis（Lour．）Spreng．）矮树灌丛、豺皮樟＋桃金娘（Litsea rotoundifolia（Nees）Hemsl．var．oblongifolia（Nees）C．K．Allen＋Rhodomyrtus tomentosa（Alton）Hassk．）矮树灌丛、大头茶（Gordonia axillaris（Roxb．ex Ker Gawl．）D．Dietr．）矮树灌丛、桃金娘＋芒萁（Rhodomyrtus tomentosa （Alton）Hassk．＋Dicranopteris dichotoma（Thunb．）Bernh．）灌草丛。DCA排序结果反映海拔高度与各个森林群落的分布格局和物种组成关系不大,而环境湿度是影响森林群落物种组成的主要因素。多样性分析结果显示,台湾相思林和土沉香林多样性指数最高,说明台湾相思林逐渐向次生林演变,除了红胶木林和少数郁闭度低的台湾相思林中有强阳生性树种外,大部分人工林下植物以阳生性稍耐阴的树种为主。调查结果显示,大榄郊野公园植物生长条件东部优于西部,西部的物种丰富度和多样性指数较低,主要以人工林和灌丛为主,加上山火频繁发生,导致长期处于先锋阶段。     

香港西贡牛尾海邻近岛屿野生植物资源的初步研究

作者通过野外调查,报道了香港西贡牛尾海邻近岛屿的植被概况和物种多样性。结果表明:该地区共有维管束植物108科254属345种。作者将其植物资源按用途分为10类:药用植物、观赏植物、材用植物、纤维植物、油脂植物、饲用植物、有毒植物、食用植物、鞣料植物和芳香植物,并论述了各类资源植物的主要种类。并对合理开发、利用和保护该地区植物资源提出了建议。     

香港次生林树种种子生理生态学特性的研究

１９８９～１９９１年在温室和野外测定了香港４０种次生林树木种类的种子寿命和发芽率．结果显示,在所测试的４０种天然林树种中,６０％的树种的种子寿命短于１年,仅有８个树种的种子寿命在１年以上．种子的寿命与种子在土壤中的发芽能力呈负相关的关系．种子发芽测定结果表明,大多数树种都可以在强光照条件（９５％的日光）下发芽,但３５％的测试树种不能在天然林下（０７％～２％的日光）发芽．最后从植物生理生态的角度,探讨种子特征与香港次生林区系发展及香港现有次生林的演替现状     

香港长洲岛野生植物物种多样性与植被的研究

长洲岛共有野生维管植物237种,隶属于73科184属.植被类型以次生常绿阔叶林为主,其次为灌丛群落.植物区系以热带亚热带植物地理成分占优势,热带性质明显.该岛的植物区系与邻近岛屿植物区系具有极大的相似性,在香港植物区系组成中占有一定地位.由于人为活动和外来植物的影响,其植物多样性及植被的保护应引起注意.