Miscellany

Species new to science from Hong Kong 1996-2001

Ricefields for wetland mitigation in Hong Kong

The mangrove stand at Lai Chi Chong - an update

Species new to science from Hong Kong 1996 - 2001

by Richard T. Corlett

As regular readers of Porcupine! will know, there are new plant and animal records for Hong Kong in every issue. Indeed, communicating these is one of the major aims of this newsletter. Most of these records are new only to Hong Kong, but a proportion of them are totally new to science. These are species for which the first scientific description – and hence the scientific name - is based on specimens collected from Hong Kong. I recently decided to find out how many such species there had been over the last five years. I have not finished counting the fungi yet but, even without them, the total described from Hong Kong during this period is an incredible 224 species! When the fungi are added in, this will come to an average of more than one new species per week. It is also very likely that I have overlooked some relevant publications.

What are these new species? Rather a lot of them are beetles – 101 to be precise. An amazing 94 of these are rove beetles, Staphylinidae, thanks to the efforts of Guillaume de Rougemont. Judging by his recent paper in MHKNHS (Rougemont, 2001), there are still quite a lot more of these to be described. Next come 38 moths, mostly described by Tony Galsworthy. Given Roger Kendrick's recent efforts, this may be just the tip of the iceberg. Then there are 22 assorted crustaceans, 12 spiders, 9 ribbon worms (Nemertea), 8 mites, 6 mayflies, 5 stick insects (Phasmida), 5 dragonflies (Zygoptera), 4 polychaete worms, 2 homopterans, 2 dinoflagellates, a fish, an angiosperm, a moss, a liverwort, an oligochaete worm, a wasp, and single species each in the orders Hemiptera, Heteroptera, Psocoptera and Pycnogonida.

Not surprisingly, a lot of these are named after Hong Kong – 30 to be precise. Most of these are Something hongkongensis, but there are several spiders with names such as Thanatus hongkong (you don't have to latinize it), a staphylinid has been named Atheta hongongiphila (Hong Kong-loving), another is Pedinopleurus hongkongicola (living in Hong Kong), and a leiodid beetle is Agathidium xianggangense. Pride of place in this list, however, must go the whole new spider genus Hongkongia (Song and Zhu, 1998). Other place names commemorated include Cape D'Aguilar, as in the littoral mite, Copidognathus daguilarensis, and several other species, Hoi Ha, in a staphylinid, Atheta hoihaensis, Sek Kong, in yet another staphylinid, plus a geometrid moth, Eupithecia sekkongensis, and other species with the epithets samchunensis (a staphylinid), maipoensis (a geometrid), taipoensis (a notodontid moth), toloensis (a crustacean) and victoria (a phasmid).

The Kadoorie family feature as both places and people, in recognition of their huge influence on ecology in Hong Kong. Eleven species incorporate the Kadoorie name in some form, but Guillaume de Rougemont tops the personal name list, with no fewer than 13 species named after him. Graham Reels is next, with 4 staphylinids and a moth. A dozen other people have one or two species named after them. My overall favourite, however, is a gnaphosid spider, Hongkongia wuae, named after both DEB postgrad Carrie Wu and her study area!

Please let me know of any new species that I have overlooked.

Bibliography

Rougement, G.M. de. (2001). The staphylinid beetles of Hong Kong. Memoirs of the Hong Kong Natural History Society 24: 1-145.

Song, Daxiang and Zhu, Mingsheng. (1998). A new genus and two new species of Hong Kong spiders (Gnaphosidae, Corinnidae). Hebei Shifan Daxue Xuebao Ziran Kexue Ban 22: 104-108.

Spiny spider, an orb-web spider (Araneidae)

A new dinoflagellate, Karenia digitata

P.21-22

Ricefields for wetland mitigation in HongKong

by Captain L.C. Wong

Long Valley has been a very hot conservation issue in Hong Kong since last year. Some of the debates have concerned the viability of the proposed re-creation of wetlands for birds. Wetland recreation is an integrated science of water chemistry, soil properties, hydrology, plant, invertebrate and bird ecology, and is certainly not dictated by ornithology. Unfortunately, the technique of wetland recreation is still not very mature, even for countries with much better knowledge of their wetlands. In the U.S.A., the success rate for mitigation wetlands is only about 27% (Marsh et al., 1996). In Hong Kong, a newspaper recently reported that 80% of the wetland grasses cultivated at Mai Po for the Wetland Park were dead. This may arouse the concern that wetland recreation is impossible in Hong Kong due to our relatively poor understanding of local wetland ecology. Being realistic, if we want to recreate a wetland for birds in HK, then we should design it in accordance with the available information and relevant experience. Local studies have demonstrated that man-made fishponds and geiwais are important for waterbirds (Wong, 1991; Young, 1998). Other than these, the most similar habitats to "natural" freshwater wetlands in South China are ricefields, which have been available in the region long enough for birds to have adapted to them.

Ricefields are temporary aquatic ecosystems that serve as valuable feeding habitats for birds in many parts of the world in both the breeding and non-breeding seasons (Fasola and Ruiz, 1996) because of their non-intertidal and shallow water nature (Gonzalez-Solis et al,. 1996). In the Mediterranean region, ricefields are considered as substitutes for natural wetlands for waterbirds like waders, gulls, terns, ducks, egrets and herons (Fasola and Ruiz, 1996). In the USA, the 140,000–180,000 ha of ricefields in the Central Valley of California, which act as a substitute for destroyed wetland habitats, support 200,000-400,000 waders, such as the Long-billed Dowitcher (Limnodromus scolopaceus) and White-faced Ibis (Plegadis chihi) (Elphick and Oring, 1998). In Japan, ricefields are also feeding habitats for egrets and herons, but concern has been expressed due to changes in agricultural practices in recent years (Lane and Fujioka, 1998).

In southern China, waterbirds were associated with ricefields in the past and still are today. Vaughan and Jones (1913), during their visit to Southeastern China in the 1910s, observed that ricefields afforded ample protection to many wading birds in the spring and autumn, and in summer to certain of the Rails (Rallidae), but they were especially famous at the right season as the haunt of the migrating Snipe (Gallinago spp.). Yellow Bitterns (Ixobrychus sinensis), Chestnut Bitterns (I. cinnamomeus) and Black Bitterns (I. flavicollis) have even nested in the ripe paddy. In Fujian, Great Egrets existed in great numbers in the paddy fields (La Touche, 1924). During summer 2000, Prof. Mauro Fasola, an Italy-based ardeid expert, found that there were 40,000 pairs of mainly Little Egrets but also Night Herons in an area of intensive rice cultivation in east-central China (Hafner pers. comm.). He also found that in this huge ricefield area of east-central China, a mixed heron colony was found about every 30 km. These observations suggest that the ricefields in this region of China are also important feeding habitats for nesting ardeids.

In Hong Kong, Herklots (1954) found that there was a seasonal use of ricefields by ardeids. He stated that "the Chinese Pond Heron (Ardeola bacchus) is associated with ricefields where they, in company with Cattle Egrets and Little Egrets, seek their food. Frogs and small fish, aquatic insects and snails are the principal foods but nothing comes amiss and a snake, a shrew or a rat would not be refused if it came within striking distance of the powerful beak of one of these birds. In the autumn the Chinese Pond Heron and Cattle Egret depart for the south but some of the Little Egrets remain: they desert the dried up ricefields and find their food in the salt-marshes or at edge of the sea following the rising or ebbing tide in company with waders. In summer, ardeids feeding in the ricefields are not gregarious, each patch may have its bird but rarely are several seen together." From his description, the ricefields may have functioned as high tide roosts for waterbirds, like the current geiwais and fishponds. Thrower (1984) suggested that ricefields, particular the paddy channels, used to be important feeding habitats for the local nesting egrets and herons, where they fed on frogs and eels. In addition to waterbirds, these man-made wetlands can also attract seed-eating birds, such as Crested Bunting (Melophus lathami) (Herklots, 1954), and probably Chinese Greenfinch (Carduelis sinica) and buntings (Emberiza spp), which was once common in the lowlands of Hong Kong (Viney et al, 1994).

Some abandoned paddy fields in and around Luk Keng still appear to be suitable for growing rice, since they are owned by the Government and rice was grown there before the 1970s. The revival of rice cultivation in this area will help to create new feeding habitats for waterbirds and ardeids, especially the Chinese Pond Heron which was the dominant breeder in the 1950s when ricefields were the dominant landuse (Hong Kong Bird Report, 1958-1969; Young and Cha, 1995). The proposed Nature Park in Long Valley may also be a good area for rice farming, which would not only provide reliable man-made wetlands for birds, but also enhance the rural character of this valley. Although the maintenance cost of ricefields may be high, they are easily recreatable and require no additional research, so they would be a good start for us to learn more about the ecology of freshwater wetlands.

However, while wetland recreation should be undertaken to make new habitats, maintaining the integrity of existing areas with high conservation and ecological value should have first priority.

Bibliography

Elphick, C.S. and Oring, L.W. (1998). Winter management of Californian rice fields for waterbirds. Journal of Applied Ecology 35: 95-108.

Fasola, M. and Ruiz, X. (1996). The value of rice fields as substitutes for natural wetlands for waterbirds in the Mediterranean region. Colonial Waterbirds 19 (Special Publication 1): 122-128.

Gonzales-Solis, J., Bernadl, X. and. Ruiz, X. (1996). Seasonal variation of waterbirds prey in the Ebro Deita rice fields. Colonial Waterbirds 19 (Special Publication 1): 135-142.

Herklots, G.A.C. (1954). Hong Kong Birds. South China Morning Post, Hong Kong.

La Touche, J.D.D. (1931). A handbook of the birds of Eastern China. Vol. 2. Taylor and Francis, London.

Lane, S.J. and Fujioka, M. (1998). The impact of changes in irrigation practices on the distribution of foraging egrets and herons (Ardeidae) in the rice fields of central Japan. Biological Conservation 83 (2): 221-230.

Marsh, L.L., Porter, D.R. and Salvesen, D.A. (1996). Mitigation banking : theory and practice. Island Press. Washington, D.C.

Thrower, S.L. (1984). Hong Kong Country Parks. Government Printer, Hong Kong.

Vaughan, R.E. and Jones, K.H. (1913). The birds of Hong Kong, Macao and the West River or Si Kiang in South-east China, with special reference to their identification and seasonal movements. Ibis 1913: 17-76.

Viney, C.A., Philips, K. and Lam, C.Y. (1994). Birds of Hong Kong and South China. 6^th ed. Government Printer. Hong Kong.

Wong, F.K.O. (1991). Habitat utilization by Little Egrets breeding at Mai Po. Hong Kong Bird Report 1990: 185-190.

Young, L. and Cha, M.W. (1995). The history and status of egretries in Hong Kong with notes on those in the Pearl River Delta, Guangdong, China. Hong Kong Bird Report 1994: 196-215.

Young, L. (1998). The importance to ardeids of the Deep Bay fish ponds, Hong Kong. Biological Conservation 84: 293-300.

P.22-24

The mangrove stand at Lai Chi Chong – an update

by Benny K. K. Chan

Mangroves are important ecological habitats and play a significant role in the ecology and economies of human society (Hogarth, 1999). Mangroves, however, are under threat globally and millions of hectares have been lost by urbanization including reclamation, pollution and human disturbance (Lean et al., 1990). Conservation of mangrove habitats, therefore, is increasingly attracting international attention. In Hong Kong, 44 mangrove habitats (a total area of 290 ha) have been identified, 23 of which having high conservation value (Yipp et al., 1995; Tam & Wong, 1997).

Lai Chi Chong (Figure 1) is one of 44 mangrove stands identified by Tam and Wong (1997) and is located in the Sai Kung West Country Park inside Tolo harbour. The area of the stand is relatively small (0.31 hectares) when compared to other mangrove stands in Hong Kong (e.g. Ting Kok and Three Fathoms Cove) and consists of boulder and sandy substratum with the most common mangrove plants Kandelia candel and Excoecaria agallocha (Tam and Wong, 1997). In their survey, Tam and Wong (1997) recorded six plant species (including 4 true mangrove plants). As a result, the mangrove stand at Lai Chi Chong was concluded to be a habitat with very low plant diversity and classified to have low conservation priority. No further in-depth surveys have been conducted (Tam and Wong, 1997).

In July 2001, I visited Lai Chi Chong during a Science Faculty function. During the field trip, I recorded a different species composition of mangrove plants when compared to Tam and Wong (1997). I suspected that the mangrove stand at Lai Chi Chong may have higher plant diversity than previously indicated and might merit higher conservation priority. Therefore, in November, 2001, I conducted transect surveys of similar design to those in Tam and Wong (1997) to record the plants and animals. I established three, 30 m, transects running from the landward to seaward region of the mangroves and in each surveyed the plant species richness and density in six continuous 5 x 5 m quadrats and scored the animal species in ten random 0.5 x 0.5 m quadrats. Infauna were sampled to a depth of 0.5 m within the quadrats.

I recorded 12 plant species (Table 1) which doubles the species of Tam and Wong (1997); the most common plant species were Pandanus tectorius, Hibiscus tilaceas, Thespesia populnea and Cerbera manghas (Fig. 1) on the landward side, while on the seaward side, the common mangrove plant species were Kandelia candel and Aegiceras corniculatum. At the seaward fringe, there was a patch of Avicennia marina (~ 30 m²) which was absent from the species list of Lai Chi Chong in Tam and Wong (1997). The plant species composition recorded in the surveys by Tam and Wong (1997) appears to under-estimate the actual species composition.

A total of 31 animal species was recorded in my survey (Table 2). In the landward fringe, the gastropod, Terebralia sulcata, the Buddhist crab, Tmethypocoelis ceratophora and the fiddler crab, Uca chloropthamalus (Fig. 1) were common. There were also considerable numbers of burrows made by the sand-bubbler crab, Scopimera globosa which leaves radiating patterns of sand grains near its burrow opening. In the mid shore region, the gastropods Cerithidia cingulata and Clithon spp. were abundant. The western part of the mangrove stand had a sandy substratum dominated by the gastropod, Batillaria zonalis and a number of bivalve species (Table 2). The bark of Avicennia marina was also colonized by the barnacle, Balanus albicostatus.

In Tam and Wong (1997), the conservation priority of mangrove stands was evaluated based on the area of the mangrove stand, species richness, species rarity, representativeness of plant species, status of current protection, degree of disturbance and nature of hazards and social values. I followed Tam and Wong (1997) in trying to calculate the scores concerning area, species richness, degree of disturbance and representativeness of the mangrove stand at Lai Chi Chong to determine its possible conservation value. I ranked all the scores calculated with the scores of the 23 mangroves recommended for further ecological studies in Tam and Wong (1997) (Table 3).

Lai Chi Chong ranked 17 out of 24 mangrove stands surveyed (Table 3). Although it is relatively small in area, it is high ranking in species richness and protection rank. Lai Chi Chong is also very remote from urban areas (it can only be accessed by ferry or a long time walk) and the mangrove stand is currently not disturbed by human activities and is unlikely to be disturbed in the coming years. With its high species richness and low risk of destruction, the mangrove stand at Lai Chi Chong should receive further ecological studies to evaluate its conservation priority.

Differences between the recent and the earlier surveys were probably due to differences in sampling design. To reduce the risk of under-estimation of species richness in a habitat, nested hierarchical sampling designs should be conducted. This type of sampling design can estimate the relative importance of different spatial and temporal scales (seasonal variations) to overall variability (see Underwood, 1997) and is therefore the most appropriate method to provide baseline information and allow future for comparative assessments.

Bibliography

Hogarth, P. J. (1999). The biology of mangroves. Oxford University Press, Oxford.

Tam, N. F. Y. and Wong, Y. S. (1997). Ecological study on mangrove stands in Hong Kong. Report submitted to Agriculture and Fisheries Department, Hong Kong SAR, 5 volumes.

Lean, G., Hinrichsen, D. and Maekham, A. (1990). Atlas of the environment.

Prentice Hall Press, New York.

Underwood, A. J. (1997). Experiments in ecology. Their logical design and interpretation using analysis of variance. Cambridge University Press.

Yipp, M. W., Hau, C. H. and Walthew, G. (1995). Conservation evaluation of nine Hong Kong mangals. Hydrobiologia 295: 323-333.

Fig. 1. The mangrove stand at Lai Chi Chong. Inserts showing a) the landward fringe was common with Pandanus tectorius, Hibiscus tilaceas and Clerodendron inerme; b) the fiddler crab Uca chloropthamalus; c) the Buddhist crab Tmethypocoelis ceratophora; d) the bivalve Gafrarium pectinatum and d) burrows made by the sand bubbler crab Scopimera spp.

Table 2. Animal species recorded in the mangrove stand at Lai Chi Chong.

P.24-26