Miscellany

	Historic coral find and a few lessons
	The significance of logan stones
	An unusual example of frugivory
	Temperate Feet in Tropical Waters
	By the way

There is a wealth of historical information on local species and habitats buried in old government reports, journals, newspapers and books. If you find something which you think should be more widely known, send it in to us!

Historic coral find and a few lessons

by Yvonne Sadovy

History, of course, helps to put things into perspective. I came across a 22-year old article from the South China Morning Post recently (26th March, 1978). It reports on the discovery by Professor (then a mere Reader) Morton and a team of divers of a large bed of living coral - 'somewhere' in Mirs Bay. A couple of things struck me about this article. The first was how much has been learned of the marine environment of Hong Kong in the last few decades. For example, the article reports that the British Museum, up until 30 years ago, did not even believe that Hong Kong waters contained coral! We now know there are at least 53 species! The second lesson is how long it takes to protect such treasures. The 'mystery' location was Chek Chau which was recommended for protection following the 1978 discovery. Nearby Tung Ping Chau, similarly coral-endowed, is only now being considered for marine protection. Chek Chau continues unprotected.

The following are abstracts from the original SCMP article:

“A Hong Kong University diving team has discovered a massive bed of perfect coral which they say is comparable to the best in Thailand or Singapore. They say the healthy coral, which is alive with colour extends down to a depth of 10 meters and completely circles a nearby island. But the name of the island in Mirs Bay is being kept a closely-guarded secret until further studies by local and international marine biologists is made.

The group’s leader, Dr Brian Morton, a reader in marine biology at the university, said he also intends to notify the Government of its existence. He said the “major discovery” was made early this week “It is about 100 yards out from the shore and goes all the way round the island. It is a perfect piece of coral and nobody knows about it”, he said.”üü..

“It’s out there for the public to see and enjoy and it should be preserved for future generations”, Dr Morton said. He said the group will recommend the Government declare it a protected area and turn it into a marine park.”üü..

 “It was only seven years ago that the British Museum refused to believe that Hongkong waters contained coral. There has been little research into the substance and it was suspected that there were only a few species of coral around”, he said.

The significance of logan stones

by Skip Lazell

In the course of my investigations of island biology I have repeatedly been faced with the question of what enables the survival of relict populations of forest-adapted species on brutally deforested land areas. The lands I have been especially interested in are aptly described by Dudgeon & Corlett (1994: 15) as: "Granite hills... with a surface cover of huge boulders exhumed as the weathered rock around them is eroded." Specifically, where a forest relict species has turned up in or close to ravine slopes into which the boulders had apparently tumbled, and where the latter were typically perched on one another so that damp, shady, almost cavernous recesses resulted. I thought forest-adapted species might have survived in these recesses when all around was reduced to grassland - or ashes. Initially, I called this the "boulder jumble" theory.

When the time came to begin a formal write-up of the fauna, however, I needed a somewhat more sophisticated characterization of the geology involved. I asked several prominent American geologists about my "boulder jumbles" before I struck one who asked me if they might be core stones? Ah, a key word, chink in the armour of ignorance. I began my computer search.

The problem with a computer search is that those who input the data and references often seem to act as though the printing press was invented about 1990. The beauty of it is that once the hare has started one can repair to the actual (as opposed to virtual) library and follow it home. I was eventually led back to David Linton who, in 1955, published The Paper That Explains Everything.

As noted by Dudgeon & Corlett (1994), most of the southwestern third of the Hong Kong region is founded on a great granitic Jurassic batholith: igneous, moulten granite that intruded beneath, but did not reach, the surface before it solidified. Subsequent soil-building episodes produced laterite: iron-rich, rust-red and acidic. Alternating cycles of erosion exposed the granite. Meantime, seismic activity cracked the batholith both vertically and horizontally. If we could back off far enough, and average the inclinations of thousands of cracks, most would fall into two categories: radial cracks, extending out from seismic centres, and horizontal cracks, parallel to the curvature of the Earth's surface. Viewed up close, the radial cracks appear vertical and the horizontal cracks appear straight, producing a subrectilinear pattern of blocks. However, the lateritic matrix speeds disintegration of the granite along the cracks and, especially, at their junctions, thus eventually rounding off the corners.

When ultimately exposed by erosion on the hilltops and along ridges, the subcubical blocks of old bedrock weather to subcircular, ovoid or pyramidal shapes. Those that remain standing are called tors; those that slump or roll away are called core stones; core stones that have tumbled together - often cracking again to make half-spheroids or half-ovoids - and are perched, are called logan stones.

A single logan stone cannot provide much of a refuge, but a good-sized ravine or a real valley chock-a-block with them might save a lot. Similarly, the likelihood of any species' survival in a logan stone refugiurn is inversely proportional to the size of the organisms in question. A hectare of logan stones will fail to save a viable population of tigers, but quite a lot of rodents, insectivores and even small carnivores might make it. Trees are unlikely to be saved in logan stone refugia, but even a single tree can perpetuate a population (no one seems concerned about inbreeding depression in trees).

 To test my theory of logan stone refugia, I suggest two complementary lines of investigation. First, locate sites dominated by sizeable conglomerations of logan stones on likely islands and search for relict forest animals. An especially likely field to search is the Wanshan archipelago, stretching away to our south and west. There are hundreds of islands out there, most quite uninvestigated biologically. Second, extend the search to flora as well as fauna. If I am right, plants - especially small, herbaceous species of the erstwhile forest floor should have survived in logan stone refugia too. Such plants will predic-tably be easier to find than are most kinds of animals. It would be especially entertaining to develop a list of candidate species, perhaps based on the known floras cited by Dudgeon & Corlett (1994) for Happy Valley and Aberdeen, or that of Tai Po Kau, or even a distant site like Dinghushan. With list in hand, let the hunt begin. Or, you can begin without it and just be amazed by what you find. That has worked for the animals.

Bibliography

Dudgeon, D. and Corlett, R. (1994). Hills and Streams - An Ecology of Hong Kong. Hong Kong University Press.

Linton, D.L. (1955). The problem of tors. Geographical Journal 121(4): 470-487. [This superb paper would have been better titled The solution of tors.]

An unusual example of frugivory

by Richard Corlett

Between flights in Chicago, I spent a couple of hours walking around the downtown area on a summer morning. In a lakeside park, an ornamental plum species (Prunus sp.) had ripe fruit. Fallen fruits were being eaten by European Starlings, Sturnus vulgaris, Canada Geese, Branta canadensis, and Ring-billed Gulls, Larus delawarensis. Most of the fruit-eating gulls were juveniles, while most adults ignored them. Although this behaviour may seem surprising for a seabird, Ring-billed Gulls are common, resident scavengers in Chicago, and our own, winter-visitor, Black-headed Gulls are known to sometimes eat fruit in their summer range, including cherries (Prunus sp.), olives and Cinnamomum camphora (Corlett, 1998).

Corlett, R.T. (1998) Frugivory and seed dispersal by vertebrates in the Oriental (Indomalayan) Region. Biological Reviews 73: 413-448.

Temperate Feet in Tropical Waters

by Kevin J. Caley

Students analysing samples on the sandy shore day

Sun, sea and sand ü what more could one ask for on a trip into the great outdoors? Well, some rocky shore would be good, with animals by the dozen and spectacular scenery. These requirements were more than adequately fulfilled by the first year Environmental Biology field course. I had been kindly invited by my colleagues in the Department of Ecology & Biodiversity to take part on this course as a visiting academic.

Almost immediately, we were thrown in at the deep end ü some of us more literally than others ü as we made the first investigations of the week, looking at a local stream.

Rhynocypha perforata, one of many odonates
that were captured on the stream day

Over that week, four different habitats were explored, all aquatic, most marine. This may be regarded as a little biased, but it does make some sense. Students are given the opportunity to compare four apparently similar environments, and discover through exploration that although general patterns may be followed, the number and type of species making up the diversity varies dramatically, even within the same general environmental theme. Being a marine biologist, I rather liked the setup anyway, but this is a personal note! However, did I learn anything on the trip?

Two features strike a biologist from temperate climes about Hong Kong’s habitats. One is the great variety of organisms and the odd places that some groups turn up in when compared to similar environments back in Britain. A notable example is the presence of crabs in freshwater streams: mitten crabs (Eriocheir sinensis) have recently been introduced to the UK, but they are an uncommon occurrence and I have yet to see my first ‘British’ one in the wild. The other feature is the large amount of rubbish, which is everywhere in Hong Kong. This really detracts from the enjoyment of any ecology trip, for fun or work, not to mention the hazards it presents ü picking your way through loads of rubbish in order to find interesting creatures is not my idea of a great time!

However, if you are a self-confessed zoology nut like me, the animals will win through in the end. A number of species seen on the course come to the fore as ‘favourites’ for me, some of which I’ll include below. Be warned, as you may notice a theme.

Barnacles of the genus Tetraclita,
rocky shore day

Fiddler-crabs come at the top of this list, marvellous pieces of evolution with semaphore-waving behaviour designed to intimidate their opponents and excite potential mates. I saw at least two species, the most notable individuals being at Hoi Sing Wan (Starfish Bay), i.e. the mid-shore Uca lactea with its brown carapace and milky-white claw, and the high-shore, much more intensely decorated, U. chlorophthalmus, one particularly bright individual of which I found cowering among the sparse stalks of some seaside herbage. Crabs abound here, among them the soldier-crabs Mictyris longicarpus, scurrying over the sand in their search for food in the sediment, looking for all the world like miniature mauve battalions on some raiding mission ü hence their name, I would imagine. I even see my first wild horseshoe crabs on this shore. Not really crabs, these animals are more closely related to spiders and are similar in general appearance to that most famous extinct arthropod group, the trilobites, although they are not closely related. Nothing like any of these animals occurs in Britain ü most of our intertidal species are shore-crabs with ‘typical’ crab-like dimensions, and hence are similar in general appearance to rock-crabs (family: Grapsidae).

Fish also figure highly in my list of notables as, for the first time, I encounter wild puffers (Fugu vermicularis), among other delights. I only find a tiny individual, but the adrenaline rush is enough to make it worthwhile!

I do have to mention the Littoraria winkles of the mangroves because, while Littorina (a related genus) are not exactly high up on my list of favourite animals, as my friends will no doubt tell you, I have always wanted to see the mangrove versions of this family. Now I have - two species in fact, very different from each other in sculpture if not in apparent shape or patterning.

Juvenile common puffer (Fugu vermicularis), before
(above) and after (below) becoming agitated

Finally, I must make space for the rocky shore. While no particular animal stands out as being very notable in itself, it has to be said that these rocky, spray-soaked places, as ever, are my favourite habitats. It was with this child-like excitement that I greeted the last day of trips, to Hoi Sing Wan’s rocky side. The shear number of animals visible to the casual observer is remarkable. Certainly, the rocky intertidal doesn’t have brightly-coloured dragonflies, nor soldier-crabs, nor even a notable array of fish species. However, it does have rock-crabs (Grapsus spp.). It also has porcelain crabs (Petrolisthes), and giant barnacles (Tetraclita spp.), hordes of mussels, limpets and, dare I say it, winkles (mostly Nodilittorina). One major difference that I should mention between the rocky shores of Hong Kong and those of Britain at this time of year is the lack of seaweed on the former, at least on the site visited ü Britain’s rocky coastline would be dominated by great drifts of wracks (Ascophyllum, Fucus); Ulva, Porphyra, Enteromorpha and Corallina would fill rock pools with a wide array of colours and shades, whilst out in the lower intertidal / subtidal region would be forests of various kelps (Laminaria spp.). On the field trip I encountered only two species of marine algal growth, both encrusting and therefore not exactly what you’d call exciting to look at ü and one of these was a cyanobacterium!

I enjoyed the trip, but did the students? I think that the answer has to be ‘yes’. They also learned a lot. The enthusiasm with which most tackled the course was exemplified by the posters, which were generally well thought out and, for the most part, contained a lot of useful ecological information. Hordes of smiling faces greeted us every day, while the atmosphere was always friendly and relaxed, with students eager to learn and not, on the whole, worried about getting wet or dirty. I think that a lot of useful field techniques were also learned, from simple censusing to catching fast-flying insects. Could they identify the animals if they were sent into the field again on their own? That I’m not so sure about, at least not without expert help, but the enthusiasm is there, which is the main thing.

Dr. Kevin J. Caley is an Honorary Assistant Professor of the Department of Ecology and Biodiversity and a Universitas21 Research Fellow of the Virtual School of Biodiversity, School of Biological Sciences, University of Nottingham, UK

Uca lactea, Hoi Sing Wan

By the way

by R. D. Hill

The notes concerning last season’s typhoons and their effects jogged my memory concerning visits to two of my field sites (for erosion control). One is on a hillside near Shau Kei Wan, on the south side of the Eastern Corridor, opposite Lei Yue Mun. The other is at Mt. Butler, adjoining the Bomb-disposal Range. At the former, but not at the latter, it was very noticeable that the tree-crowns were mostly browned off and dying on the side facing the sea. York was a fairly dry typhoon and it seems likely that a fair amount of sea salt was entrained and deposited dry upon leaf surfaces on the windward side of tree-crowns. The “salt-storm” phenomenon is well-known along coasts where salt is carried inland by prevailing winds, deposited upon leaves and, in the partial ü or complete ü absence of rain is not washed off. Such dry deposition quickly damages the tissues, presumably at least in part because of desiccation.

In Hong Kong storms are usually accompanied by a great deal of rain so that such salt as may be deposited would soon be washed off. The salts would be added to the soil, of course, though in what quantity, with what residence-time and what effects no one knows. In other places sea salt has been detected a 100 km inland, while close to the sea annual additions of up to 40 t ha yr have been measured. Maybe there’s a nice little study here for a chemically-minded ecologist.