Tai Po Kau Research Articles

Monoculture plantations impede forest recovery: Evidence from the regeneration of lowland subtropical forest in Hong Kong

Anthropogenic disturbance has led to widespread clearance and degradation of tropical forests, and tree planting has been promoted as an effective solution for recovery. However, trees have been overwhelmingly planted in monocultures or low-diversity mixes and this is expected to have profound, lasting impacts on forest structure, diversity, and functioning. In this study, we tested the extent to which historical vegetation transition types (VTTs) constrain forest recovery in a secondary tropical landscape in Hong Kong, South China. To do so, we overlaid vegetation types (forest, shrubland, pine plantation, grassland) identified in aerial photographs taken in 1956 and 1963 of a 20-ha plot situated in Tai Po Kau Nature Reserve, allowing us to define six historic VTTs, namely: FF (forest to forest), GP (grassland to plantation), GS (grassland to shrubland), SS (shrubland to shrubland), SF (shrubland to forest), and SP (shrubland to plantation). We compared present-day forest structure and species diversity among these VTTs, as determined from a census conducted in 2015, using incidence- and abundance-based rarefaction and extrapolation, and we assessed species’ association within VTTs using a torus translation test. Our results reveal that stem density and species diversity in naturally regenerated forests were more similar to those of old-growth forest, whereas species diversity in areas occupied by pine plantations was significantly lower as compared with naturally regenerated areas. Despite 60 years of recovery, pine plantations were characterised by a significantly greater proportion of negatively associated species, and late-seral species were still predominantly confined to old-growth patches. Present-day species distribution is chiefly explained by the combined effects of topography and VTT (17.1%), with VTT alone explaining 4.4%. Our study demonstrates that VTT has a significant long-term impact on forest regeneration and community assembly and, importantly, that monocultural plantations (forest plantation) can greatly impede forest recovery. Remnant old-growth forest patches merit priority protection, and active restoration, including thinning and enhancement planting, is necessary to facilitate forest succession.

First record of the genus Leonardiella in China, with the description of the Leonardiella pappi sp. nov. from Hong Kong (Acari: Mesostigmata: Trachyuropodidae)

Leonardiella pappi sp. nov. is described based on six females and two males collected from soil under Machilus sp., in Tai Po Kau Nature Reserve, in Hong Kong. The new species differs from the other species from the congeners in the shape of dorsal and ventral setae and dorsal and ventral sculptural pattern. A new diagnosis to the genus Leonardiella and a new catalog to all known species are given.

Rotundabaloghia (Rotundabaloghia) dogani sp. nov. from Hong Kong (Acari: Mesostigmata: Rotundabaloghiidae)

Rotundabaloghia (Rotundabaloghia) dogani sp. nov. is described based on three females and one male collected from soil in Tai Po Kau Nature Reserve, in Hong Kong. The new species differs from the other species from the subgenus Rotundabaloghia in the shape and length of the ventral setae.

Comparative assessment of soil quality parameters after implementing afforestation programme in forest areas of Hong Kong.

The objective of this research is to investigate and compare the alteration of soil parameters with and without afforestation programme in a Hong Kong forest, analysed by Principal Component Analysis (PCA). One hundred soil samples were collected from the following sites: Pak Ngau Shek (PNS), Shing Mun (SM), Tai Po Kau (TPK), Tai Tong (TT) (forest with afforestation programme) and Lantau Peak (LP) (control site). A significant difference was found in only two out of 16 parameters: pH (8.34-8.87) and PAHs (4.35-6.32μg/kg) by comparing the soils taken in the forest with and without an afforestation programme implemented. Three principle components are responsible for soil quality variations in the studied sites. The first, second and third components included pH (0.167) and EC (0.176), PAHs (0.331) and PAHs (0.207), respectively. This framework provides information on the least disturbance of soil properties for the afforestation programme. To conclude, a rigorous monitoring of soil quality is necessary to assess forest health after an afforestation programme. Besides, in the long term, an appropriate forest preservation programme should be implemented to achieve rural area sustainability.

Flocking behavior of forest birds in Hong Kong, South China

This paper reports observations of flocking behavior of birds in a well-protected secondary forest in Tai Po Kau Nature Reserve, Hong Kong Special Administrative Region, China. A total of 1025 flocks including 5255 birds and 48 species were observed between October 2002 and November 2003. Most flocks consisted of only one species. The observed flocks averaged 1.79 ± 0.05 (SE) species and 5.13 ± 0.18 (SE) birds. The Japanese White-eye was the most numerous species and was present in 21.6% of the observed flocks. Seasonal trends in both flock size and number of species were similar to those in overall bird density and species richness in the study area reported in a previous study.

Do adult snails in headwater streams make upstream migrations to compensate for spate-induced washout? A test using three populations of a tropical caenogastropod

Stream snails are known to exhibit upstream migration in temperate and tropical regions (see reviews by Huryn & Denny, 1997; Kappes & Haase, 2012). This behaviour can be driven by a variety of factors depending on species and circumstances, including the search for food, predator avoidance and compensation for washout or catastrophic drift during spates (e.g. Schneider & Frost, 1986; Schneider & Lyons, 1993; Snider & Gilliam, 2008). Recolonization of upstream habitats via migration can replenish losses due to spate-induced washout (Kopp, Jeschke & Gabriel, 2001) and could be an important mechanism contributing to population persistence (Speirs & Gurney, 2001; Pachepsky et al., 2005). Upstream migration may also be a mechanical consequence of snails orientating themselves to reduce hydrodynamic drag (Huryn & Denny, 1997; Covich, 2010). Within a species, migration patterns vary in relation to individual size and growth (e.g. Schneider & Lyons, 1993; Shigemiya & Kato, 2001; Snider & Gilliam, 2008; BlancoLibreros & Arroyave-Rincon, 2009). Upstream migrations of snails in tropical and subtropical streams have been mostly documented in amphidromous Neritidae (Blanco & Scatena, 2005, and references therein), which have plankotrophic larvae that require saline conditions for development. Juveniles must therefore migrate upstream from estuaries to adult habitats where they mature and breed (McDowall, 2007; Crandall, Taffel & Barber, 2010; Gorbach et al., 2012). The caenogastropod pachychilid Sulcospira hainanensis (Brot, 1872) is widespread in tropical streams in southern China (including Hong Kong, Guangdong and Hainan) and northern Vietnam (Kohler & Glaubrecht, 2001; Yeung & Dudgeon, 2014b). Sulcospira hainanensis is not amphidromous; it spends its entire life in fresh water and larvae are incubated in a cephalic brood pouch prior to their release in the form of miniature adults (Kohler & Glaubrecht, 2001). Wet-season declines in abundance have been recorded in this species, likely due to washout during spates (as high as 85%; Yeung & Dudgeon, 2014b). Upstream migration may therefore be necessary to compensate for this downstream displacement, which might otherwise result in long-term decline in snail densities in the upper courses of streams. There are few studies of migration by non-amphidromous caenogastropds in tropical streams, but Cochliopina tryoniana (Pilsbry) (Hydrobiidae) in Costa Rican streams exhibits upstream migratory behaviour, moving at rates of up to 110 m d (Schneider & Lyons, 1993). These streams receive frequent spates in the wet season, analogous to those in Hong Kong, and we consider it likely that the upstream migration of C. tryoniana is a compensatory response to downstream washout during this period, rather than having the life-history role seen in freshwater neritids (Schneider & Lyons, 1993). We hypothesized that S. hainanensis would show upstream migrations as a compensatory response to spate-induced washout. This was tested using a year-long mark-and-recapture study of three populations in Hong Kong. The study populations inhabited second-order stream at Tai Po Kau (TPK), and third-order streams at Pak Ngau Shek (PNS) and Shing Mun (SM) in the mainland New Territories of the Hong Kong Special Administrative Region of the People’s Republic of China (Yeung & Dudgeon, 2013: fig. 1). The TPK site (elevation: 180 m) was situated at mid-altitude and other sites (PNS: 110 m; SM: 300 m) in the lower half in their respective drainage basins. These sites were thus not close to the uppermost distributional limits of snails, which allowed the detection of any active upstream migration. Snails were present both upstream, and at various distances downstream of the study reaches, and physical conditions upand downstream were similar. Hong Kong has a tropical monsoonal climate, with the wet season (May to August) in 2011 (the year when the study was conducted) receiving 42% (1,007 mm) of the mean annual rainfall of 2,399 mm, which is typical of the seasonal pattern of precipitation (Hong Kong Observatory, 2011). Spates (.50 mm rainfall in 1 d) were frequent during this period (Hong Kong Observatory, 2011). The study sites encompassed a wide range of canopy closure (PNS: 40%; TPK: 80%; SM: 90%), with consequent differences in algal food availability (Yeung & Dudgeon, 2014a). Most other physical characteristics were similar in these streams, where the waters were slightly acidic and welloxygenated (see Yeung & Dudgeon, 2013; Table 1). Therefore, the sites chosen broadly represent the stream environment that the snails inhabit in Hong Kong. Monthly collections of 80–100 S. hainanensis individuals were made from January 2011 to January 2012 (except July 2011) along a 20-m study reach at each of the three sites. They were marked individually by uniquely identifiable bee tags (Opalith Numberplates for Queens, Item 112,902, Swienty A/S Company, Sonderborg, Denmark) attached to the shell with Aron Alpha Instant Glue super glue gel (Toagosei America Inc., West Jefferson, United States). Individuals ,1.5 mm aperture width

Discovery of the second species of Pseudohypocrea (Hypocreaceae)

A new species of the monotypic genus Pseudohypocrea is described based on a collection from Tai Po Kau, Hong Kong, China. The fungus is characterized by globose to subglobose perithecia entirely immersed in a pulvinate reddish-brown stroma, cylindrical asci with smooth-walled and lemon-shaped part-ascospores, and occurring on dead leaves. Morphological features of the new species are described and compared with the only known species of the genus.poi

Railway tunnel portal noise

Railway tunnel portal noise is a concern in environmental impact assessment for railway projects. Railway noise is amplified inside the tunnel due to multiple reflections of highly sound reflective tunnel walls and such noise is then radiated from the tunnel portal. Noise Sensitive Receivers (NSRs) which are situated in close proximity of railway tunnel portal are adversely affected by the portal noise radiation in additional to the ordinary railway noise. Standard railway noise calculation procedures (Calculation of Railway Noise by Dept of Transport in UK, Transit Noise and Vibration Impact Assessment by Federal Transit Administration in USA, etc.), however, do not include a correction for such portal noise effect. This paper presents the experimental results of railway tunnel portal noise collected from Tai Po Kau tunnel on the East Rail Line in Hong Kong and proposes appropriate the tunnel portal noise corrections.

Are autochthonous foods more important than allochthonous resources to benthic consumers in tropical headwater streams?

Increasing evidence suggests that autochthonous foods are the principal basis of consumer production in tropical forest streams, despite the predominance of terrestrial detritus inputs. The relative importance of autochthonous and allochthonous energy for the dominant benthic consumers was investigated in 3 tropical headwater streams with different shading conditions in Hong Kong with a combination of assimilation-based analyses: stoichiometry, C and N stable isotopes, and fatty acid (FA) profiling. The snail Brotia hainanensis (Pachychilidae), shrimps Caridina cantonensis (Atyidae) and Macrobrachium hainanense (Palaemonidae), and their potential basal food sources (leaf litter, fine particulate organic matter [FPOM], periphyton, cyanobacteria, and filamentous algae) were collected in Tai Po Kau Forest Stream (shaded 1), Shing Mun Stream (shaded 2), and Pak Ngau Shek Stream (open) during the 2004 dry season (January and February). All samples were analyzed for C:N ratios, δ13C, and δ15N values. Total FAs were extracted from each sample, and concentrations of 35 important FAs were analyzed by gas chromatography–mass spectrometry (GC–MS). C:N ratios of algal foods were markedly lower than those of terrestrial detritus and similar to those of the test animals at all 3 sites, a result that suggested that autochthonous sources were relatively more nutritious than were allochthonous sources. Autochthonous foods were more 13C and 15N enriched than were allochthonous foods at all sites. The algal sources contributed to 29 to 98% of consumer biomass, generally more than was attributed to the terrestrial sources (2–71%). Consumers also showed distinctive FA profiles indicating consumption of autochthonous foods, especially periphytic diatoms and cyanobacteria, as revealed by the elevated concentrations of FA biomarkers such as palmitoleic (16:1[cis-9]) and eicosapentaenoic acids (20:5[all cis-5,8,11,14,17]) in the consumers, periphyton, and cyanobacteria. Our results suggest that autochthonous resources are possibly more important than allochthonous foods to secondary production in tropical headwater streams.

Effects of leaf toughness and nitrogen content on litter breakdown and macroinvertebrates in a tropical stream

High plant diversity in the tropics results in leaf litter of widely differing quality that may affect litter breakdown rates in streams. The effects of leaf toughness and nitrogen content on litter breakdown rates and macroinvertebrate colonization were investigated in Tai Po Kau Forest Stream, Hong Kong during dry seasons in 3 different years, using 7 species of leaves (Arundinaria shiuyingiana, Ficus fistulosa, Indocalamus sinicus, Liquidambar formosana, Livistona chinensis, Melaleuca quinquenervia, Pandanus furcatus) with contrasting characteristics. Liquidambar formosana (Hamamelidaceae) was included as a benchmark species (for comparison) in all 3 dry seasons, but the identity of the other leaf species varied among years. There was no significant inter-year difference in breakdown rates of L. formosana. Leaf toughness was the primary determinant of breakdown rates, which were negatively correlated with leaf strength. Soft leaves had faster breakdown rates than tough leaves, irrespective of their nitrogen content. Collector-gatherers dominated (>60% of individuals) macroinvertebrate assemblages on litter, and obligate shredders were scarce (1–6%). Toughness and nitrogen content of leaves were not good predictors of the composition of litter-associated macroinvertebrate assemblages, which were similar among leaf species studied within the same season. There were, however, small but significant inter-year variations in macroinvertebrate assemblages on L. formosana litter, mainly due to changes in predator abundance. The absence of a deterministic link between leaf quality and macroinvertebrate assemblage composition suggests that litter served as a substrate rather than a food source for macroinvertebrates, and may account for the scarcity of shredders in tropical streams.

Reproduction and Sexual Dimorphism of the Palaemonid Shrimp Macrobrachium Hainanense in Hong Kong Streams

Macrobrachium hainanense is a large palaemonid shrimp (total length up to |$7\;{\rm{cm}}$|⁠) present at high densities (⁠|$ \gt 2$| individuals |${{\rm{m}}^{ - 2}}$|⁠) in pools of low-order forested streams in Southern China. The present study investigated the reproductive biology and sexual dimorphism of this shrimp in Tai Po Kau Forest Stream (TPK) and Tai Shing Stream (TSS), Hong Kong. Recruitment occurred during the wet season (May to August). Macrobrachium hainanense, a truly freshwater species, has abbreviated larval development, and the study populations had smaller broods than euryhaline species of this genus. Most females probably produced only a single brood of |$20 - 75$| eggs each breeding season. They showed no size-specific fecundity. Egg development in the laboratory took over 53 days, and eggs grew larger during development. The reproductive output (RO) of females was |$11\% $| for each brood, lower than for most other species of Macrobrachium. Lifetime RO was |$21\% $|⁠, assuming a single brood in each of two seasons. The population male-biased sex ratio was 1.7:1, although the size-specific sex ratio was 1:1. Females reached maturity at |$15 - 17\;{\rm{mm}}$| carapace length (CL) while males matured later at |$18 - 22\;{\rm{mm}}\;{\rm{CL}}$|⁠. Females bred at two and three years of age, while males bred three times at two, three, and four years. Interstream variation in size at onset of sexual maturity was found, with shrimps at TPK maturing later than at TSS. Discriminant Analysis revealed that mature males and females were distinct in their abdominal depths and carapace lengths with females having deeper abdomens (for egg brooding) and smaller carapaces. Juvenile males could be distinguished from females by the presence of the appendix masculina. The minimum lifespan for females of M. hainanense was approximately 29 months and for males, 48 months. Competition for females may be responsible for the longer lifespan and larger size at maturity of males.

Foodweb structure in a tropical Asian forest stream

AbstractA food web based on the gut contents of consumers (invertebrates and fishes) in pools of Tai Po Kau Forest Stream (TPKFS), Hong Kong (southern China), indicated the importance of periphyton and fine organic particles; coarse particulate organic matter was a less important food source despite its higher relative abundance in this shaded hillstream. Stable isotope analysis of consumer tissues was undertaken to confirm this result. IsoSource software was used to model n-isotope and >n + 1-sources, so that the relative contribution of the potential food sources could be determined. Results of an IsoSource mixed model of δ15N and δ13C stable isotope signatures of primary consumers generally supported evidence from gut content analyses about the importance of autochthonous resources. Inconsistencies between the results of gut content analysis and isotope signatures of consumer tissues occurred in a few cases but could be explained either by small sample size or the wide range of feasible solutions provi...

Effects of Macrobrachium hainanense predation on benthic community functioning in tropical Asian streams

Summary1. Macrobrachium hainanense is a large predatory palaemonid shrimp, present at high densities in pools of low‐order forested streams in Hong Kong. The present study investigated the impacts of M. hainanense on benthic community structure and functions in pools of two streams: Tai Po Kau Forest Stream and Tai Shing Stream.2. Repeated whole‐pool experiments involving shrimp density manipulations (removal, control and addition) were conducted in both streams between October 2000 and April 2002, and included a wet (May to September) and two dry (October to April) seasons. The three objectives of the study were to determine the effects of M. hainanense predation on benthic macroinvertebrate abundance and species richness, rates of leaf litter breakdown because of effects on detritivores, and periphyton standing stocks by way of an effect on herbivores.3. Wet season results showed consistent reductions in benthos densities and species richness following heavy rainfall, irrespective of shrimp manipulation. These results suggested that spate‐induced disturbances might override biotic effects and play a dominant role in structuring benthic communities in stream pools in Hong Kong.4. No significant, reproducible effects on any of the response variables measured in either stream were found during the dry season. Litter breakdown was reduced in the absence of shrimps during one experiment only, suggesting it might be a type I error. These results signified no effect of shrimp removal on benthic communities, or on the functional processes of litter breakdown, or on periphyton accumulation. The large scale of the experimental units (8–40 m2), refuge availability, and the presence of benthic predatory fishes that cropped excess prey made available by removal of M. hainanense, may have contributed to the lack of any effect, despite the abundance of the predatory shrimps.

Dietary variation in a predatory shrimp Macrobrachium hainanense (Palaemonidae) in Hong Kong forest streams

Macrobrachium hainanense is a large palaemonid shrimp (total length >7cm), present at high densities (>2 individuals m -2 ) in pools of low-order forested streams in Hong Kong, Southern China. The present study investigated the diet and trophic status of this shrimp in pools of Tai Po Kau Forest Stream (TPK) and Tai Shing Stream (TSS). Macrobrachium hainanense was a generalist predator that fed selectively on sedentary and slow-moving prey (snails, chironomid larvae and calamoceratid caddisflies) eating them disproportionately relative to their abundance in pool benthic communities. Shrimp diets varied by size of the individual, by season and by stream. The diet of large males was dominated by the thiarid snail Brotia hainanensis, and ovigerous females had guts that were half as full as large females although their diet was similar to other life stages. Gut fullness was reduced in shrimps that had molted recently. Over 80 % of the food items eaten by M. hainanense at TPK during the wet season were B. hainanensis, while the dry season diet included a greater number of taxa including tube-dwelling Chironomidae (31 %), Trichoptera (25 %) and Ephemeroptera (24 %). This pattern of seasonal variation was less noticeable at TSS than at TPK. TPK M. hainanense had less full guts (∼ 50 %) than those at TSS (∼ 70 %), but, at both sites, shrimps with empty guts were encountered only during the wet season. The predaceous nature of M. hainanense through all life stages is in contrast to the omnivorous or detritivorous habit of other Macrobrachium species. The results of δ 15 N and δ 13 C stable isotope analysis of samples from TPK confirmed the predatory trophic status of M. hainanense. All life stages had isotopic signatures that were higher than to sympatric predatory invertebrates (e. g. Odonata). Allochthonous detritus made no direct contribution to the assimilated tissue of M. hainanense.

Life histories, production dynamics and resource utilisation of mayflies (Ephemeroptera) in two tropical Asian forest streams

SUMMARY 1. A 2‐year study of the life histories, production dynamics and resource utilisation of five mayfly species was undertaken in two forest streams in Hong Kong [Tai Po Kau Forest Stream (TPKFS) and Shing Mun River (SMR)]. Afronurus sp. and Cinygmina sp. (Heptageniidae), Procloeon sp. and Baetiella pseudofrequenta (Baetidae), and Choroterpes sp. (Leptophlebiidae) were abundant in both streams and contributed more than 50% of the total mayfly populations.2. All species had asynchronous larval development with recruitment occurring throughout the year. Mean annual production (all mayflies combined) was 3.1 and 2.0 g dry weight m−2 year−1 in SMR and TPKFS, respectively – the higher value at SMR reflecting greater mayfly densities – with more than 70% of production occurring during the wet season. Mayfly production varied between years, decreasing by 5% in TPKFS and 43% in SMR during 1996–97, reflecting lower densities of heptageniids relative to 1995–96. Annual biomass turnover rates (P/B) were high in both sites ranging from 27.2 to 94.6 in TPKFS (Cinygmina sp. and Procloeon sp.) and from 31.8 to 109.8 in SMR (Cinygmina sp. and B. pseudofrequenta).3. Patterns of daily production in both streams showed that Afronurus sp., Cinygmina sp. and Choroterpes sp. were most productive during the wet season, while Procloeon sp. maintained high production levels throughout the year. The highest daily production of B. pseudofrequenta occurred during the wet season in TPKFS, but in the dry season at SMR. Temporal overlap in production and hence resource utilisation in both streams, calculated using the proportional similarity index (PS), ranged from 0.39 to 0.81. It was highest (0.63–0.81) between pairs of species of Heptageniidae and Baetidae, and lowest between Choroterpes sp. and other mayflies (0.39–0.61). No clear temporal segregation was observed among any species. However, when using the fraction of production attributable to each food, lower PS values were obtained for all species in both sites. In SMR, trophic segregation may have occurred between the two species pairs Procloeon sp.–Cinygmina sp. and Procloeon sp.–Choroterpes sp. (PS=0.17 and 0.03, respectively).4. A combination of production data and information on the stable isotope signature of mayflies revealed that, during both the wet and dry seasons, more than 50% of total mayfly production in TPKFS was derived from autochthonous foods. In SMR, 68% of production was supported by allochthonous foods during the wet season, and 72% by autochthonous sources in the dry season. Considering that more than 70% of the total production occurred in the wet season, the trophic basis of mayfly production in SMR is mostly allochthonous (58%) while in TPKFS it is mainly of autochthonous origin (66%). The year‐round importance of autochthonous foods in shaded streams such as TPKFS is surprising, but the wet season contribution of allochthonous foods (especially in SMR) may have resulted from depletion of algal biomass during spates.

Laboratory and field studies of mayfly growth in tropical Asia

Growth of seven species of mayflies in three families (Baetidae, Leptophlebiidae and Heptageniidae) was investigated in the laboratory (Procloeon sp. 2 and Chopralla sp.), in the field (Cinygmina sp. and Baetiella pseudofrequenta), or both (Afronurus sp., Procloeon sp. 1 and Choroterpes spp.). Animals were reared in laboratory tanks and or in field cages at three sites in two Hong Kong (lat. 22° 17'N) streams, Tai Po Kau Forest Stream (TPKFS) and an open and shaded section of the Lam Tsuen River (LTR: LTRO and LTRS, respectively). Growth rates (mg mg -1 d -1 ) in the laboratory ranged from 0.12 (Afronurus sp.) to 0.3 (Procloeon sp. 1), and from 0.059 (Cinygmina sp.) to 0.23 (B. pseudofrequenta) in the field. All species were multivoltine. Baetids could complete more than eight generations a year, heptageniids at least four, and Choroterpes (Leptophlebiidae) up to eight. The influence of food quantity on growth was measured under laboratory and field conditions, while the effect of temperature was studied by rearing mayflies in the field throughout the year. In the laboratory, some mayfly species grew faster when reared on food collected from LTRO than from LTRS but in situ growth rates of Afronurus sp., Cinygmina sp. and Choroterpes spp. were similar in both LTR sites. No significant differences in growth rates among any sites were found for B. pseudofrequenta and Procloeon sp. 1, but growth rates at TPKFS were generally lower than at LTR for most species. Mayfly growth increased linearly with temperature, explaining 23-77 % of the total variation in field growth rates throughout the year.

Fungal communities on submerged wood from streams in Brunei, Hong Kong, and Malaysia

Fungi on submerged wood in streams are a diverse group, comprising taxa from various families. Fungal communities on submerged wood collected from Sungai Sitam in Brunei, Tai Po Kau Forest Stream in Hong Kong, and from a stream in Lipur Lentang Nature Reserve in Malaysia are reported. One hundred and forty-seven taxa were recorded. A higher species diversity including temperate and tropical species was recorded in Tai Po Kau Forest Stream in the subtropics. Ascomycetes and their asexual stages were dominant in tropical and subtropical freshwater habitats, while discomycetes were rare in these habitats. Distinct fungal communities are found on submerged wood in tropical, subtropical and temperate regions and these are discussed. Including the fungi identified in this study, over 1000 fungi has been recorded from freshwater habitats.

Stable-isotope determination of mayfly (Insecta: Ephemeroptera) food sources in three tropical Asian streams

Carbon and nitrogen stable isotopes were used to determine the foods assimilated by mayflies in three Hong Kong streams: Tai Po Kau Forest Stream (Forested 1), Shing Mun River (Forested 2), and an open (Open 1) and a shaded section (Shaded 1) of the Lam Tsuen River. Analyses were carried out during both wet and dry seasons. A total of seven mayfly species (Heptageniidae, Leptophlebiidae and Baetidae; four or five species per site) were included. During the dry season, mayflies in the two forest streams (I and 2) fed mainly on autochthonous foods (33-100 %) especially cyanobacteria and Cladophora spp. in Forested 1. During the wet season, the use of allochthonous food increased (13-100 %) in Forested 1 and 2, but the importance of autochthonous foods in shaded streams with ample stocks of detritus was nevertheless surprising. Mayflies in both Open 1 and Shaded 1 derived most of their biomass from a variety of autochthonous foods during both seasons, but epilithon was the dominant wet season food. Moreover, allochthonous foods did not appear to contribute significantly to the diet of mayflies during any season at Shaded 1. When compared with published literature, these results suggest that use of allochthonous foods in tropical streams may be greater than in temperate latitudes where allochthonous energy sources appear to dominate community energy flows in small streams.

Torrentispora fibrosa gen. sp. nov. ( Annulatascaceae) from freshwater habitats

Torrentispora fibrosa gen. sp. nov. (Ascomycota, Annulatascaceae) is described based on specimens from submerged wood collected from streams in Tai Po Kau Forest Reserve, Hong Kong. T. fibrosa is characterized by immersed to superficial ascomata with a peridium of black cells arranged in irregular rows, wide septate paraphyses, long cylindrical asci with a relatively massive refractive apical ring, and unicellular ascospores with a fibrillar sheath. Illustrations from light and scanning electron microscopy are provided. It is compared with species in the genus Annulatascus, from which it differs in ascoma peridium and ascospore sheath morphology, and with other aquatic ascomycetes possessing ascospores with a similar fibrillar sheath structure.

Indiscriminate Feeding by a Predatory Stonefly (Plecoptera: Perlidae) in a Tropical Asian Stream

The diet of an undescribed species of Kamimuria was investigated in Tai Po Kau Forest Stream, Hong Kong, by comparing larval gut contents with the array of available prey living on and among cobble substrates. Diets were dominated by chironomids and philopotamid caddisflies, with Baetidae, Heptageniidae, Hydropsychidae and Simuliidae comprising secondary dietary items. These six taxa made up 94% of the prey individuals eaten by Kamimuria. Data analysis using a selectivity index revealed that these stoneflies fed indiscriminately, eating individual prey taxa in proportion to their availability in the environment. Large and small Kamimuria exploited essentially the same prey. A comparison of the diet of Kamimuria with the diets of four sympatric Odonata indicated that the degree of interspecific similarity was determined by the extent of overlap in microhabitat use. Diets of Euphaea decorata (Zygoptera) larvae, which live under cobbles, were most similar to Kamimuria. This is the first – albeit limited – study of the gut contents of a tropical Asian stonefly. The results suggest that these predators have the potential to limit benthic invertebrate abundance but, because Kamimuria larvae feed unselectively, community structure may not be affected by their activities.