State-level marine park planned in Dapeng New Area

Dapeng New Area – just across Mirs Bay from Hong Kong – is planning to build a national marine park according to the Shenzhen Daily newspaper. The aim is to “create the first coral-themed marine ecological system in the country”, by which I think is meant the first man-made coral ecosystem in China.

Dapeng will install artificial reefs to connect the coral reef communities in Da’ao Bay with those in the Tung Ping Chau area of Hong Kong, in the hope of providing a good marine ecological environment

Dapeng New Area has commissioned marine protection organizations to install 68 artificial reefs and plant more than 13,000 coral seedlings in the sea area in recent years.

The new area said it will draw on the experience of Hong Kong’s marine parks and adopt tough protective measures to provide a good environment for the reproduction and growth of the coral reefs.

By joining hands with the Hong Kong Underwater Association they want to establish the first diving research base on the mainland to improve awareness of marine environmental protection and encourage NGOs to participate in coral conservation.

Currently there are 39 diving organizations in the new area.

Over the past two years, volunteers have completed 12 cleaning operations and salvaged more than 448 kg of marine waste, including fishing nets, fishing cages and plastic bags.

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The Stingrays of Hong Kong

I have just added a page about all the different species of ray that are found in Hong Kong. Here is a little preview on just the stingrays. Check out the full list of rays here.

The Stingrays of Hong Kong:

 

Round ribbontail Ray / Black-spotted stingray (Taeniura meyeni)

Round Ribbontail Ray (via WikiCommons)
Round Ribbontail Ray (via WikiCommons)
A bottom-dwelling inhabitant of lagoons, estuaries, and reefs, generally at a depth of 20–60 m (66–197 ft). Reaching 1.8 m (5.9 ft) across. Generally nocturnal, the round ribbontail ray can be solitary or gregarious, and is an active predator of small, benthic molluscs, crustaceans, and bony fishes. Although not aggressive, if provoked the round ribbontail ray will defend itself with its venomous tail spine. In Hong Kong, it is found mainly in the relatively clear southern and eastern waters, but it has also been found in the northern part of Lantau and in brackish water near the Pearl River estuary. It is also one of the species that has been found on Hong Kong’s artificial reefs. Check out Eric Keung’s spooky photo of a this stingray in Hong Kong waters.
Between July 2005 and June 2008 there were two cases of people being stung by stingrays in HK – fortunately with mild outcomes. The sting and its venom can cause bluish or greyish discoloration around the wound, disproportionate pain, muscle cramp, weakness, seizure, hypotension, cardiovascular toxicity, deep wounds and lacerations. In other words, stingrays are dangerous! Just watch from a distance and don’t touch!


Blue-Spotted Stingray (Neotrygon kuhlii)

Blue-Spotted Stingray, Papua New Guinea (via WikiCommons)
Blue-Spotted Stingray, Papua New Guinea (via WikiCommons)
The body is rhomboidal and green with blue spots with a maximum width estimated at 46.5 centimeters (18.3 in). The rays coloration is a warning for the highly poisonous barbs, thus few animals attempt to overpower this ray. In HK, they are more easily seen in summer in the shallow water along the coast, on coral reefs and in mangrove areas. Because of the venomous sting observers should not get too close or try to touch it!


Pale-edged stingray (Dasyatis zugei)

Pale-edged Stingray (via WikiCommons)
Pale-edged Stingray (via WikiCommons)
A bottom-dwelling ray most commonly found over sandy areas shallower than 100 m (330 ft) and in estuaries. It measures up to 29 cm (11 in) across, has a diamond-shaped pectoral fin disc, a long projecting snout, small eyes, and a whip-like tail. It is chocolate-brown above and white below and feeds mainly on small crustaceans and fishes. In HK it is mainly found in the western Pearl River estuary south of Lantau Island.

Extinct in Hong Kong – the Maxima Clam (Tridacna maxima)

The giant clam Tridacna gigas which can grow to 120 in width and 200 kg in weight is one of a group of clams called giant clams – the Tridacnids. Although T. gigas is the biggest of them, there are others which are still pretty huge by clam standards. One of these giant clam species, the Maxima clam Tridacna maxima, used to occur in Hong Kong. It grows to about 40 cm width, though typically is only around 20 cm in width. But consult the IUCN records for this clam species and you will see that although it occurs throughout the tropical and sub-topical waters of the Indian and western Pacific Oceans, the entry for Hong Kong sadly reads ‘regionally extinct’. When did that happen? Why did they vanish? These are the questions I wanted to find answers to.

When did it go ‘regionally extinct’?

The first entry I could find for the Maxima clam being regionally extinct in Hong Kong is 1983. Unfortunately that’s about all I could find. But at it has been gone from Hong Kong since at least 1983. Unless of course it has returned….its a slow-growing animal but has a very wide dispersal through free-floating larvae that live in the plankton – that’s why it occurs over such a wide geographical area spanning nearly a quarter of the planet! So theoretically, if conditions are right (see more below) and larvae are swept over Hong Kong or are purposely introduced by humans, the Maxima clam could reestablish itself in Hong Kong.  So the next question is why did it go extinct in Hong Kong in the first place?

a Maxima clam tucked into some hard coral (via WikiCommons)
a Maxima clam tucked into some hard coral (via WikiCommons)
What happened to the Maxima clam in Hong Kong?

Apart from the fact that the Maxima clam lived on coral reefs in Hong Kong waters, I can not find any more details of how big the population was, which exact areas in inhabited (obviously coral reefs, so that narrows it to Eastern and Southern Hong Kong waters) or whether it was harvested locally. It is however clear that Hong Kong used to be a big regional market for giant clam species in Asia. Giant clams were and still are a delicacy in Asia (mostly the meat big abductor muscle) and the shell was used for decoration (though not extensively). Even the UN Food and Agriculture Organization has no useful fisheries statistics for Tridacnids. So there is no information on how many – if any – were harvested from Hong Kong waters before they disappeared.  The maxima clam like all clams is a filter feeder which suck in water, filters out and swallows edible particles and then ejects the water out again. As such it is quite vulnerable to toxic substances in the water. In addition, it harbors symbiotic microscopic algae called zooxanthellae (zoo-oh-zan-the-lay) in its tissue. These absorb the clams waste  products like CO2 and photosynthesize turning them into sugars in the presence of sunlight and giving off oxygen for the clam.

When open, the bright blue, green or brown mantle of the clam is exposed and obscures the edges of the shell which have prominent distinctive furrows. The attractive colours of the mantle are the result of pigment cells, with a crystalline structure inside. These are thought to protect the clam from the effects of intense sunlight, or to bundle light to enhance photosynthesis of the zooxanthellae.

 

1024px-Coral_reefs
Maxima clams – one open showing the brightly colored mantle, the other closed and only identified by the zig-zag pattern of the shell valves. (via WikiCommons)

This is essentially what corals do, too, which is why they share the same habitat – coral reefs. And like most reef corals the maxima clam also gets most of its nutrients from its zooxanthellae . Coral reefs suffer enormous damage from smothering by sediment that washes into the sea from rivers and rainfall and from clouding of the water and smothering by excessive algal blooms. Both of these were and still are to some extent big problems for Hong Kong waters, whereas in the past this was not the case. Algal blooms and sediment runoff increased a lot as a result of the increase in human population in Hong Kong and as a result of rapid industrialization and the associated water pollution. This combined with harvesting seems to be the most likely reason for the disappearance of the Maxima clam from Hong Kong waters before 1983.

Will there ever be giant clams in Hong Kong again?

I hope so. Like I said earlier, if conditions are right, any of the wide-ranging planktonic larvae of the clam that stray into Hong Kong waters could settle and grow to adulthood. Failing that humans could also try to establish them by attaching cultured juveniles to appropriate spots on reefs – but this is more complicated and costly, although Singapore has attempted this with initial success using another giant clam species Tridacna squamosa. But the main criteria is suitable conditions for a population to establish and grow – in other words we need clean seas again. Hong Kong has improved a lot on this front up until very recently, when the increased coastal development in southern China started to create a lot of water pollution which somewhat diminishes the results. There is still a long way to go. But I would say that divers should keep an eye out. In fact, the ReefCheck 2015 recorder forms even have a section for giant clams (Tridacna sp.), so its not just me that is hopeful! You never know. you could be diving some coral reef in Sai Kung, Tung Ping Chau, Hoi Ha Wan or the Ninepin Islands and come across a maxima clam. It might be an old dead one stuck in a reef with just the wavy outline of the two shell valves (probably) or it could have the fat, bright blue or green mantle of a live clam – in which case 1) hooray for Hong Kong and 2) please report your finding to the AFCD and Reef Check!

Pristine Coral Reefs Destroyed by ‘Great Wall of Sand’

China is creating a ‘great wall of sand’ in the South China Sea, according to the Daily Mail.

The latest huge land mass is four square kilometres in size and was created by dumping sand on live coral reefs, damaging local ecosystems.

But this is just one of several artificial islands China has been creating in the region – and the exact purpose of them is unknown.  

 

 

The large expanses of sand and concrete – the latest being Johnson Reef – are being built among the Spratly Islands in the South China Sea.

China is creating the area by using dredging vessels to dig up sediment from the sea, and then dumping it on subermeged coral reefs to make islands.

China has supposedly been carrying out the land reclamation in order to build airstrips and other structures in the region.

  

Five islands in total have been built in this way, and two more are in development. 

Richard Dodge of the Nova Southeastern University Oceanographic Center, said: ‘The activities described would appear to clearly both be greatly exceeding corals and coral reefs’ ability to cope and survive the excess sediments and turbidity.’

He said that as the reefs were being covered by cement and landfill, this constituted ‘outright destruction’ of the buried coral reefs and associated habitats. 

‘Coral reefs are extremely globally and locally valuable both for the biodiversity and ecosystem they create but also for the tremendous services they provide in terms of food supply, cultural heritage, erosion prevention, recreation, tourism, and habitat for myriad other organisms,’ he continued.

‘Coral reefs worldwide are under extreme threat from changing climate and from local sources of land based pollution, over fishing, and coastal construction.

‘The activities described would appear to represent an additional and severe threat to coral reef ecosystem health and sustainability.’

  

Robert Nicholls, a Professor of Coastal Engineering at the University of Southampton, added: ‘It is clearly destroying [coral reefs] at the local scale of the land claim and the environment.

‘In the bigger scheme of things it is harder to be precise as these are small areas in a large area of reef.’

China is creating land by pumping sand on to live coral reefs – some of them submerged – and paving over them with concrete. It has now created over 4 square kilometers of artificial landmass.

The region is known for its beautiful natural islands, but ‘in sharp contrast, these actions are are creating a great wall of sand with dredges and bulldozers over the course of months.

Southeast Asian Territorial Disputes Are Literally Killing Off Coral Reefs

This week Bloomberg’s Adam Minter wrote a great article on the plight of the South China Seas coral reefs and their large scale destruction in the name of territorial Claims by China, Taiwan, Vietnam and the Philippines.
I have written about this previously (here and here), and I am happy that a professional journalist – for a widely-read news publisher no less – has devoted some time and effort to bringing media coverage to this issue.
Below are some new and interesting insights from extracts of the article ( BloombergView “Victims Under The South China Sea” 26/11/2014).

[…] in the South China Sea, where nations seeking to enforce their territorial claims have not always spent much time worrying about the environmentally and economically valuable reefs under the waves. How valuable? A 2011 report to the UN General Assembly on coral reefs noted that seafaring Asian nations count between 100,000 and “more than” 1 million coral reef fishers among them.

One might think that governments, pressed by those fishermen, would be striving to preserve fragile reef systems. But just the opposite has happened. According to a 2013 study by Australian and Chinese scientists, the South China Sea’s atolls and archipelagos have seen their coral cover decline to 20 percent from averages of 60 percent or more just 10 to 15 years ago.

The large-scale reclamation of reefs for military purposes is just the start of the damage. What happens after can oftentimes be much worse. “If 1,000 soldiers are stationed at any one time in a place, they typically cut down vegetation and cause runoff, generate sewage,” says Terry Hughes, a marine biologist and director of the Queensland-based Australian Research Council Centre of Excellence for Coral Reef Studies.

Draining into the sea, runoff is deadly for coral: In coastal China, where cities also tend to discharge effluent into the ocean, 80 percent of all coral has died off. In 1980, the amount of coral cover near a large Taiwanese military outpost in the disputed Spratly Islands was 60 to 70 percent. By 2007 it had declined to 17 percent, according to the 2013 study, which Hughes led.

That sort of damage is likely to grow more common: In October, Taiwan’s top intelligence official revealed that China has seven ongoing South China Sea construction projects. When complete, they’ll join at least 20 additional reclamations owned by four other South China Sea claimants.

Even worse than the direct damage from construction projects is the political deadlock caused by various territorial disputes. The biggest threat to coral is the large-scale use of cyanide and explosives by the region’s fishermen. As Hughes’s 2013 study pointed out, at just one atoll, the number of fishing boats using cyanide and dynamite to kill fish increased nearly eight-fold between 1996 and 2001. By 2001, “virtually everything harvestable (e.g., fish, mollusks, crustaceans, echinoderms) had been stripped from the atoll.”

Rogue fishermen are the immediate culprits, but a lack of governance and oversight allows them to continue their depredations. While that’s no secret to any of the six South China Sea claimants, they’re unlikely to agree on where or how to protect coral if they can’t agree on boundaries first. Instead individual countries have tried to impose fishing limits unilaterally, which no one else follows. “When it comes time for governance, everyone puts their hand up and that means no one,” says Hughes.

Nonetheless, Hughes remains optimistic, if only because corals can regenerate when protected and given time. (Decades are needed.) He suggests that in the absence of a broader agreement on regulating the South China Sea, scientists from the region might begin the discussion on how to protect reefs. Translating any recommendations into action won’t be easy. But it’s probably the best option for ensuring that soldiers and tourists won’t be the only living creatures left to enjoy the seas.

(Featured image shows structures built on top of Johnson Reef)

The Long-Spined Urchin (Diadema setosum)

When I was a boy snorkelling off beaches one of the sights I best remember and one of the potential hazards was the long-spined sea – Diadema setosum. Its quite a beautiful creature with black or brown-banded spines that are extremely long and narrow. They are also hollow and contain a mild venom which -despite being painful – does not pose a serious threat to humans. And if you have ever stepped on one you’ll know the spines are fairly brittle so getting them out is tricky!

They have a black skeleton shaped like a squashed ball that houses all the organs which is called a ‘test’ and essentially that’s the body of the urchin. Get close enough and you will see a bright, orange ring around the urchin’s “anus” (which is on the top of the urchin as you look at the seabed) and some bluish spots surrounding the orange ring. Similar blue spots are arranged in linear fashion along its test.

20140429-195558.jpg

Adult urchins weigh 35 – 80 grams and measure no more than 7 cm in test diameter and around 4 cm in height. But the spines make them look much bigger!

It is commonly found on coral reefs, but also on sand flats and in seagrass beds. Its range stretches throughout the Indo-Pacific from the Red Sea and then eastward to the Australian coast, then as far north as Japan and as far south as the southern tip of the African east coast. Interestingly it has been introduced into other localities not within its natural range. For example in 2006, two living specimens were found in waters off Turkey.
In Hong Kong it’s very common and lives all across the coast of Eastern Hong Kong as well as the southern side of Lamma and probably anywhere where there is coral or rocks with reef-type algae. Check out Hong Kong Reef Check for more info on its distribution in Hong Kong waters.

During the day they hide in a sheltered crevice and at night they leave it to graze on a variety of algal species in an area about 1 m around their crevice. Very hungry individuals may become carnivorous. They can also bite bits of the rocks and corals producing coral sand as debris.

In Hong Kong they probably spawn in summer when the water temperature reaches at least 25 degrees. But other cues, such as a full moon may affect the spawning, too. They need to live in high densities to reproduce because males and females stimulate the opposite sex to spawn by releasing chemicals into the water and that’s only possible when there lots of them in one place. Females release 10-20 million eggs at each spawning, hoping that at least a few of them will get fertilised by the sperm the males release into the water at the same time. The fertilised eggs develop into larvae that will live and drift for 40-50 days as plankton before settling on the seabed. When the larvae finally settle on a naked rock somewhere, they metamorphose – that is transform into real sea urchins. It’s a bit like caterpillars and butterflies or tadpoles and frogs. Incidentally, almost all marine invertebrates go through such a metamorphosis. Frequently they live below another urchins spines to protect themselves from enemies.

20140429-200312.jpg

In Hong Kong the long-spines sea urchin has been suspected of causing damage to reefs (along with some other invertebrates), so that the government has at least once undertaken manual removal of these urchins from the Hoi Ha Wan Marine Park. There is ssome research into this topic going on at the Swire Institute of Marine Sciences (HKU).