Mycorrhizal associations in Hong Kong Fagaceae

Polyphenols histochemically detected in fresh uninfected roots of Quercus, Castanopsis and Lithocarpus growing in Hong Kong and shown to be condensed tannins were found mainly as intracellular material in the cells of the root cap, the epidermal layer and the endodermis. The cell walls of the outer cortex and the endodermis also contained suberin. Following invasion by compatible ectomycorrhizal symbionts, condensed tannins disappeared from cells of the root cap and the epidermal layer but hyphae were prevented from colonizing the cortex presumably due to suberin barriers. In vitro experiments indicated that a number of broad-host ectomycorrhizal fungi could utilise various polyphenolic compounds, including tannins found in the root exudates of the host trees, with different degrees of efficiency.     

香港茜草科植物新记录

查阅馆藏植物标本,有3种茜草科植物：丹草（Hedyotis herbacea）、小耳草（H.pumila）和蕴璋耳草（Scleromitrion koanum）为香港新记录。这些资料为香港的生物多样性工作提供了基础数据。     

Large subunit rDNA sequences from Alexandrium catenella strains isolated during harmful algal blooms in Hong Kong

The partial sequences of the large subunit (24S) ribosomal RNA gene(LsurRNA) of three Alexandrium catenella strains isolatedduring the 1998 and 1989 red tide incidents in Hong Kong were compared,togetherwith the sequences of other Asian A. catenella speciescomplex. The sequences of two A. catenella strainsisolatedin 1998 were identical, despite being isolated at different time (March andApril) and different locations (eastern and southern Hong Kong). In cladisticanalysis, the two A. catenella HK98A & B strains, theA. catenella HK1989 strain, the Chinese strain clade andtheKorean/Japanese A. catenella form a clade distinct fromother A. catenella strains. Interestingly, the twoA. catenella HK98A & B strains only form a clade withtheA. catenella HK1989 strain/ChineseA. catenella (CCMP1493) with low bootstrap values (49%).     

香港桦木科一新种——香港鹅耳枥(英文)

报道了桦木科(Betulaceae)鹅耳枥属(Carpinus L.)一新种——香港鹅耳枥(C.insularis N.H.Xia,K.S.PangY.H.Tong)。香港鹅耳枥与太鲁阁鹅耳枥(C.hebestroma Yamamoto)及多脉鹅耳枥(C.polyneura Franch.)相似,但习性灌木状,叶具13~16对侧脉,先端锐尖,边缘锯齿的芒尖较短,果苞宽半卵形或半卵形,长8~14 mm,小坚果顶端密被长柔毛且疏具树脂状腺体,与后两者易于区别。     

Burrow Architecture of the Ghost Crab Ocypode ceratophthalma on a Sandy Shore in Hong Kong

The ghost crab Ocypode ceratophthalma (Pallas) creates burrows of variety shapes at different ages. Juveniles (mean carapace length 11 mm) produced shallow J-shaped burrows, which incline vertically into the substratum (mean depth 160 mm). Larger crabs (17–25 mm carapace length) have Y-shaped and spiral burrows (mean depth 361 mm). These Y-shaped burrows have a primary arm, which extends to the surface forming the opening, and a secondary arm which terminates in a blind spherical ending. The two arms join in a single shaft and end with a chamber at the base. The secondary arms and chambers are believed to be used for mating or as a refuge from predation. The spiral burrows have spiral single channel ending in a chamber. Older crabs (mean carapace length 32.6 mm) had simple, straight single tube burrows, which inclined into the substratum at mean of 73° and had a mean depth of 320 mm. During summer daytime periods, the burrows shelter the crabs from heat and desiccation stress. The sand surface temperature at the burrow opening was ~48 °C but temperatures inside the burrows can drop to 32 °C at a depth of 250 mm. Variation in the burrow architecture with crab age appears to be related to the crab’s behaviour. Juvenile crabs have smaller gill areas and move out of the burrows regularly to renew their respiratory water and, as a result, they do not need a deep burrow. Larger crabs, in contrast, can tolerate prolonged periods without renewing their respiratory water and therefore create deeper and more complex burrows for mating and refuges.     

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     

A new species ofAppendicospora from Hong Kong

A new species ofAppendicospora, A. honkongensis, occurring on fronds ofLivistona chinensis in Hong Kong is described and illustrated with interference contrast micrographs. It differs fromA. coryphae in having larger ascomata and ascospores, and a peridium of brown-walled cells. The differences betweenApiospora andAppendicospora are reexamined in the light of the cultural characteristics of the latter.     

Macrobenthos of a tidal impoundment at the Mai Po Marshes Nature Reserve,Hong Kong

The composition and spatial distribution patterns of the macrobenthic faunal assemblages of an 8-ha tidal impoundment operated as a traditional shrimp pond at the Mai Po Marshes Nature Reserve, Hong Kong, were studied in relation to temporal changes in local environmental conditions. Species richness, abundance and biomass of macrobenthos across 5 different sub-habitats (seaward, middle, and landward parts of open water unvegetated areas, and Phragmites- and Kandelia-dominated, vegetated areas) within the pond were examined bimonthly between January 1997 and January 1998. Grab samples were collected randomly within the sub-habitats. Key physical environmental parameters of the sampling sites were also measured. A total of 46 species of macrobenthos was recorded: 11 polychaetes, 11 molluscs, 13 crustaceans and 11 insects. Mean species density in the five sub-habitats ranged from 0 to 3907 indm^–2, with mean biomass ranging from 0 to 96.9 gm^–2. The macrobenthos showed spatial and temporal differences among the sub-habitats and across sampling times. Species abundances of Polychaeta, Mollusca and Crustacea were significantly higher in the three open water areas than in the two vegetated (Phragmites- and Kandelia-dominated) areas, with an inverse pattern for Insecta. There were no clear temporal patterns although abundance and biomass generally increased in the cooler months. Results of a canonical correspondence analysis suggest that macrobenthic species richness, abundance and biomass in the open areas were positively correlated with salinity, while water depth, dissolved oxygen and sediment organic matter content had little relationship with the macrobenthic assemblage parameters. Ordination by multi-dimensional scaling suggests that different habitats supported distinct macrobenthic assemblages. The macrobenthic assemblage in the tidal pond was less species rich but denser than those in the neighboring tidal mangrove and mudflat, suggesting that conversion of these areas into extensively managed tidal aquaculture ponds results in reduced species richness in tropical mangrove habitats.     

The population dynamics of some freshwater carideans (Crustacea: Decapoda) in Hong Kong,with special reference to Neocaridina serrata (Atyidae)

During a 15-month investigation of the population dynamics of three caridean shrimp species in the Lam Tsuen River, New Territories, Hong Kong, the numbers of the commonest species, Neocaridina serrata (Stimpson)(Atyidae), were reduced as water temperatures fell. By contrast, Caridina lanceifrons Yu became more numerous during the winter. The relatively scarce Macrobrachium hainanense (Parisi)(Palaemonidae) tended to be more abundant during the summer, and the abundance of this species was directly correlated with that of N. serrata. The population size of these two species was positively correlated with water temperatures prevailing one and two months prior to the collection of samples, but there was no significant relationship between C. lanceifrons abundance and water temperature.All species exhibited similar growth patterns with an inflection at the attainment of sexual maturity, occurring after the (presumed) 14th moult for N. serrata and in the (presumed) 13th and 18th stadium for C. lanceifrons and M. hainanensis respectively. Ovigerous shrimps of all species were only recorded when water temperatures exceeded 20 °C and the % incidence of ovigerous N. serrata was positively correlated with prevailing temperatures. It is suggested that restriction of freshwater caridean breeding periods by low temperatures may be common in the subtropics while perennial breeding is more likely to be typical of tropical regions.The mean carapace length of N. serrata populations was negatively correlated with prevailing temperatures, but more strongly correlated with temperatures recorded one and two months prior to sampling when gametogenesis may have taken place. Smallest mean sizes were recorded in late summer upon the cessation of juvenile recruitment. N. serrata has a maximum longevity of approximately 12 months and reproduction occurs in the 7th month of life or later. The hatchlings are well developed and clutch size is not related to the size of the brooding female. An annual life cycle, as seen in N. serrata, may be typical of many small freshwater carideans.Department of Zoology, The University of Hong Kong     

Phenology of Sargassum spp. in Tung Ping Chau Marine Park, Hong Kong SAR, China

Eight species of the brown alga Sargassum have been recorded from Tung Ping Chau Marine Park in Hong Kong and the phenology of four of these was monitored from 1996 to 2000. All four species followed a typical growth cycle of Sargassum species reported elsewhere but with some annual variations. For S. hemiphyllum, the maximum mean (±SD) plant length, ranging from 38.5 ± 10.5 to 61.9 ± 19.9 cm, was recorded in January to March. The peak reproductive season was also mainly in February to March with up to 89% of the plants being reproductive. Some plants, however, remained reproductive until May. For. S. henslowianum, the maximum mean plant length, ranging from 45.5 ± 25.5 to 77 ± 24.8 cm, was recorded mainly in November to January. The peak reproductive season was in November to February with up to 100% of the plants being reproductive. For S. siliquastrum, the maximum mean plant length, ranging from 48.2 ± 29.9 to 63.4 ± 22.1 cm, was also recorded mainly in January. The reproductive plants were found mainly between late December and mid February with up to 98% of the plants being reproductive. For. S. patens, the maximum mean plant length ranging from 87.6 ± 62.4 to 118.7 ± 41.3 cm was recorded in January to March. Reproduction of this species was not monitored. Changes in water temperature over seasons were likely to be critical in affecting the phenological patterns of these species.     

香港潜蝇科(双翅目)的分类研究

报道了香港22种潜蝇科昆虫,其中包括5新种、6个中国大陆新记录种。新种模式标本分藏于下列两处： Melanagromyza squamifera sp. nov., Ophiomyia imparispina sp. nov., Phytomyza redunca sp. nov.的模式标本保存于日本东京自然博物馆; Melanagromyza dipetala sp. nov., Ophiomyia vasta sp. nov.的模式标本保存于美国夏威夷比肖普博物馆。     

香港蜘蛛区系研究

本文报道了香港地区蜘蛛2个新纪录科29个新记录种,并初步分析了香港蜘蛛区系的特点。香港蜘蛛共计24科90属148种,特有种占20％,区系组成与新加坡近似。     

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.     

Antiviral polysaccharides isolated from Hong Kong brown seaweed Hydroclathrus clathratus

Two relatively pure polysaccharides H3-a1 and H3-b1 had been isolated from the brown seaweed Hy-droclathrus clathratus. They were characterized by HPLC, ultraviolet scanning, gas chromatography, infrared spectroscopy and elemental analysis, and shown to be two different sulfated polysaccharides with different monosaccharide content, but both with high relative molecular mass. They contained some proteins and uronic acid respectively. The sulfate content and bioactivity of these polysaccha-rides varied during purification. The fractions derived from the hot water extract also exhibited low anticoagulant effect. This is the first time that the antiherpetic and anticoagulant activities were evaluated for the polysaccharides from the Hong Kong brown seaweed Hydroclathrus clathratus.     

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。     

香港蕨类植物新记录

报道了香港蕨类植物新记录种5种,即台湾轴脉蕨(Ctenitopsis kusukuensis)、掌叶线蕨(Colysis digi-tata)、德化鳞毛蕨(Dryopteris dehuaensis)、海岛鳞始蕨(Lindsaeaorbiculatavar.commixta)和石松(Lycopo-diumclavatum),其中包括两个新记录属轴脉蕨属(Ctenitopsis)和石松属(Lycopodium)。另外,还列出了每个种的重要特征及其与相关种类的差异。     

香港樟科一新种-腺叶琼楠

报道樟科琼楠属-新种,即腺叶琼楠Beilschmiedia glandulosa N．H．Xia,F．N．Wei ＆ Y．F．Deng。腺叶琼楠与美脉琼楠B．delicata S．Lee ＆ Y．T．Wei和网脉琼楠B．uangii Men∏．近似,但叶面具腺状小突起,花序短和果实表面光滑,不具小瘤点而容易区别。     

香港桃金娘科一新种—凹脉赤楠

对香港桃金娘科蒲桃属一新种,凹脉赤楠Syzygium impressum N．H．Xia,Y．F．Deng ＆ K．L．Yip作了描述,它与赤楠S．buxifolium Hook． ＆ Am．近似,区别在于叶倒卵形,中脉下凹,果直径约4mm。     

Mineral element content in Ulva lactuca L. with reference to eutrophication in Hong Kong coastal waters

The amounts of tissue nitrogen, phosphorus, potassium, sodium, calcium and iron were estimated in the green alga Ulva lactuca L. collected from 9 rural and 14 urban littoral sites in the waters around Hong Kong Island during 1978 and 1979. The mean levels of tissue nitrogen and phosphorus were respectively 65% and 87% more in urban sites than in rural ones. Very significant correlation (r = 0.920) was found between the logarithmic concentration of seawater inorganic nitrogen and that of tissue nitrogen. The same applied to soluble reactive phosphorus in seawater and tissue phosphorus (r = 0.886). The levels of potassium, sodium and calcium in the alga were relatively uniform. However considerable variation in the level of iron was detected. The potential use of Ulva as an indicator species for eutrophication is discussed.