The Starfish of Hong Kong, Part 2

Blue Linckia (Linckia laevigata)

Blue Linckia via WikiCommons cc-by-sa 3.0

Ranges in color morphs from dark or light blue, but also observed as aqua, purple, or even orange variations throughout the ocean. Grows up to 30 cm in diameter and has rounded arm tips. Some individuals can have lighter or darker spots along their arms. They are typically firm in texture and have slightly tubular arms with short, yellowish tube feet on the underside. It inhabits coral reefs and sea grass beds. They occur subtidally, sometimes intertidally, on fine sand or hard surfaces and move quite slowly .

Cushioning Star (Culcita nouvaeguineae)

via WikiCommons (Shizhao, cc-by-sa-2.5)

The cushion star has very short arms and an inflated appearance, resembling a pentagonal pincushion. Its colour is variable and it occurs in tropical warm waters in the Indo-Pacific. It ranges from Madagascar and the Seychelles to the Philippines, New Guinea, Australia and Hawaii.  It feeds on detritus and small invertebrates, including stony corals.

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The Starfish of Hong Kong, Part 1

Crown-of-Thornes (Acanthaster planci)

Crown-of-Thornes starfish

The crown-of-thorns starfish is a large starfish with many arms that preys on hard coral. Its name comes from the venomous thorny spines covering its upper surface – meant to resemble the crown of thorns put on Jesus before his crucifiction. This is one of the largest starfish and has a very wide distribution in the Indian and Pacific Oceans at tropical and subtropical latitudes where coral reefs or hard coral communities occur.

The venom of the starfish contains so-called asterosaponins which have detergent-like properties. The brittle spines can perforate the skin of a predator or unwary diver and tissue containing the venom is lodged into the resulting wound. In humans this immediately causes a sharp, stinging pain lasting several hours, with persistent bleeding aided the venom as well as nausea, tissue swelling lasting for a week or more. Breaking of the spines means they become embedded in the tissue where they require surgically removal.

Peppermint Sea Star (Fromia monilis)

The peppermint sea star can grow to a diameter of about 30 centimetres. Its arm tips and the central disc are bright red, while the other parts are paler, forming large plates. The color, plates and other features can be very variable and identification from photographs can be difficult. It feeds on encrusting spongess, detritus and small invertebrates. Occurs in shallow water in rocky environment, at a depth of 0 – 51 m.

Hong Kong’s Amazing Marine Biodiversity Highlighted by MarineGEO-Hong Kong”

Local and international scientists joined with HKU’s Swire Institute of Marine Science and School of Biological Sciences for an intensive, 10-day marine life survey through some of Hong Kong’s most disturbed and pristine marine environments. From the heavily impacted, inner Tolo Harbor to the more isolated, coral rich Tung Ping Chau, scientists identified over a thousand representative specimens of fish, crabs, snails, bivalves, worms and more across an estimated 300-400 total species.

Scientists are still working to identify each of these specimens which are also being documented through high resolution photography and genetic characterization, or barcoding. In fact, many specimens are stumping the expert taxonomists suggesting that there will be newly described species of hermit crabs and bivalves to come. Not all biodiversity is good news however, several invasive species were also identified which can cause disruptions to local ecosystems. In addition to identifying all of those organisms that they could see, scientists will use the latest technologies in genetic identifications to detect organisms that are too small to be recognized by the naked eye.

ARMS settlement plate deployed in Tung Ping Chau for two years. Many of these eight-level ARMS structures were found to have over 300 visible organisms living within.

ARMS settlement plate deployed in Tung Ping Chau for two years. Many of these eight-level ARMS structures were found to have over 300 visible organisms living within.

The survey methods were developed by the Smithsonian Institution’s Marine Global Earth Observatory research program (MarineGEO), which is “the first long-term, worldwide research program to focus on understanding coastal marine life and its role in maintaining resilient ecosystems around the world”. In 2016, The University of Hong Kong became the first official MarineGEO site in Asia and hopes to serve as a node for future expansion in the region.

The ARMS were transported back to HKU and each plate was removed one at a time while making sure not to lose any organisms large or small.

A single plate from one ARMS structure measures ~25 X 25 cm. High resolution photographs like this one allow for visual identification of attached organisms including sponges, encrusting algae, tube worms, ascidians, and more. Scientists will look at not just who is there but also how their abundance changes around Hong Kong.

A single plate from one ARMS structure measures ~25 X 25 cm. High resolution photographs like this one allow for visual identification of attached organisms including sponges, encrusting algae, tube worms, ascidians, and more. Scientists will look at not just who is there but also how their abundance changes around Hong Kong.

One of the strengths of the MarineGEO project is the standardization of methods used to quantify biodiversity. The multilevel settlement structures, or ARMS, are approximately 0.5 m2 and resemble a marine invertebrate version of Hong Kong’s famous high-rises. To survey the existing biodiversity HKU scientists deployed twelve ARMS in Hong Kong in May 2015 and collected them in October 2017, with plans to deploy and collect data for 40 more ARMS across Hong Kong as far west as Lantau Island. In addition to providing a baseline biodiversity assessment, through time, this legacy project will allow scientists and governments to better evaluate human impacts on the marine environment and which interventions are most efficient at preserving biodiversity. To find out more and keep track of ongoing projects, visit the website at https://marinegeo.si.edu/hong-kong-china.

Students and scientists brush off and pick through everything that is not firmly attached to the ARMS plates looking for organisms such as crabs, shrimp, snails and more. These are sorted by eye, counted, and passed to a taxonomic expert. They will also be sampled to determine the genetic sequence that corresponds to the taxonomic identification and build a library of genetic diversity for future use.

“MarineGEO is a legacy project which SWIMS has committed to lead for years to come. Although the project is global in scale, our grassroots efforts provide a new means of monitoring Hong Kong’s changing marine environment from negative factors like climate change and development, and positive factors like improved management and restoration, said” Dr. David Baker, Project Principal Investigator.

As a last step of ARMS sampling, all remaining material is scrapped from each plate and combined for one large, genetic characterization of the entire plate community. Individual “barcodes” are expected to number in the tens of thousands per ARMS.

“The amount and diversity of tiny creatures in Hong Kong waters is astonishing. Even more so considering how impacted the habitat is by the millions of people here,” added Dr. Till Roethig, SWIMS post-doctoral fellow. “It was exciting to connect everyone, from local students to global scientists, to the amazing diversity which makes Hong Kong a special and important site for conservation in the region,” said Dr. Shelby McIlroy, also a SWIMS post-doctoral fellow.

A group of local and international scientific collaborators take a break from the day’s work to flex their ARMS muscle. 

“As undergraduates, we had fun participating in this project. There were many benthic organisms that we had never seen before. The beautiful colours of sea slugs and the sound that snapping shrimps made were very memorable. We were also lucky to witness the biodiversity along with all the admirable researchers,” Chan Mei Yin, Chan Sze Wen, Lee Tsoi Tao Esther, Tsui Teresa Ka Wing and Wong Yu Yeung, Gary echoed.

Credit: “Dr David Baker’s research team at HKU’s Swire Institute of Marine Science and School of Biological Sciences”

The Living Fossils of Hong Kong and Richard Fortey’s Survivors – Part 1

Having briefly worked in the Natural History Museum in London, i had the pleasure of listening to a lecture by Richard Fortey who is known for a whole list of popular science books. One of these books, as ibrecently found out has nearly a whole chapter set in Hong Kong and dealing with some of Hong Kong’s lesser known marine animals.

In “Survivors: the Animals and Plants That Time Has Left Behind”, Richard Fortey visits East Sai Kung Country Park with Professor Paul Shin of City University, to explore some mudflats looking for creatures that are rare survivors of past geological ages millions of years ago.

You may be familiar with this animal:

Credit Citron / CC-BY-SA-

The coelacanth is a lobe-finned fish thought to be the ancestor of all land vertebrates. Having evolved 400 million years ago, it was thought extinct for 66 million years until famously it was discovered living in 1938. That made it the poster boy for living fossils. But few Hongkongers would suspect a living fossil in their city, let alone 4!!!

One of these is Lingula anatina. It consists of two valves forming a clasped shell and a long stalk or pedicle. The pedicle is buried vertically in the sediment to anchor the animal while its valves open to filter tiny edible pieces out of the sea water at the sediment surface. 

Lingula anatina (via Wikicommons)

To an untrained eye this might seem like mussel or clam or other mollusc. But it is in fact a brachiopod, a group of animals that has been around for about 500 million years. To put that into context, the colonisation of land by plants happened 400 million years ago. How a brachiopod differs from a mussel or clam is its internal organs and body structure – but that’s a matter for undergraduate invertebrate textbooks….

Lingula for all its similarity to a mussel, is not a mollusc, but the next living fossil is.  The chiton Acanthopleura japonica is very ancient and primitive mollusc.

A chiton preserved in its rolled up state after becoming detached from its rock surface

The animal is similar to a snail but instead of a shell it has 8 armoured plates which it locks together to form a shield. They use a muscular foot to glide around rocks scraping algae off them. If scared or at low tide they suck themselves onto the rock with their foot and at the same time lift their shell to form a vacuum – so prying them off rocks is not recommended as you will only end up breaking and killing them. If they do get pried off rocks they roll up a bit like a wood louse. Acanthopleura is a common sight around Hong Kong’s rocky shores. And chitons very similar to it started appearing about 450 million years ago…for context, dinosaurs appeared about 200 million years later…and in all that time they really haven’t changed much.

The third living fossil is a type of worm. The Peanut-worm to be precise, so named because it can bunch itself into a peanut-shaped blob. Its proper name is sipunculid worms, and they too have been around for almost 500 million years. As with brachiopod sand mussels, the difference between a sipunculid and a ‘regular’ marine worm is in its internal body structure and organs. Hong Kong actually hosts at least two species of sipunculid worm. One of these is Siphonosoma cumanenses, pictured below. It makes burrows on fine sandy shores.

Live specimen of Siphonosoma cumanenses collected in Fort Pierce, Florida. Photo by Kawauchi, Gisele Y. by myspecies.info licensed under CC BY-NC-SA

The other is Sipunculus nudus, pictured below, which is – not surprisingly – also eaten in Southern China.

A bucket of deliciously-looking purple worms (labeled 即劏北海沙虫 – “‘Sand worms’ from Beihai, at a street vendor in Guangzhou. Photo by Vmenkov via WikiCommons licensed under CC-BY-SA 3.0
Live specimen of Sipunculus nudus (dorsal view) collected in Fort Pierce, Florida. Photo by Kawauchi, Gisele Y. From myspecies.info licensed under CC BY-NC-SA
 
Finally, there are the horseshoe crabs, but that is for Part 2…

Hong Kong Underwater Photo Competition Winners 2017 Announced

The Hong Kong Underwater Photo and Video Competition 2017 jointly organised by the Agriculture, Fisheries and Conservation Department (AFCD) and Hong Kong Underwater Association, announced its winning entries.

The Hong Kong Underwater Photo and Video Competition, in its 6th year now, received 436 entries this year, featuring marine ecology, habitats and marine life in Hong Kong waters.

An AFCD spokesman said, “Entries over the years have showcased the beauty of marine life and habitats in Hong Kong waters, and have helped promote the conservation of the marine environment.”

The event comprised a photo competition and a video competition. There were two categories in the photo competition, namely the Macro and Close-up Category and the Standard and Wide Angle Category. In addition to prizes for champions and runners-up in each group, there were Special Prizes for Junior Underwater Photographers presented by the judging panel to encourage less experienced underwater photographers to participate in the competition.

Please click the thumbnail images to enlarge.

New Species of Tree-Climbing Crab Discovered in HK

Haberma tingkok that’s the name given to a new species of mangrove crab that climbs in trees along the eastern coast of Hong Kong. It was collected from branches between five and six feet high.

It has a dark brown upper shell, or carapace, long, thin legs that are light brown, and its claws, or chelipeds, are a brownish orange.

Mangrove crabs are quite small. The collected specimens measured between 8 and 9 millimeters in length, less than a third of an inch.

Scientists from the University of Hong Kong and the National University of Singapore described the new species in the journal ZooKeys.

The genus Haberma now contains three species. Peter Ng, a marine biologist at NUS and co-author of the latest study, established the genus 15 years ago and helped discover all three species (the other two are H. nanum and H. kamora).

H. tingkok was named after the Ting Kok mangrove stand, in Tolo Harbour, where it was found in the mid intertidal area. The area is the largest mangrove stand on the eastern coast of Hong Kong.

Hong Kong’s mangroves and the species they shelter are under threat from pollution and land reclamation projects.

Image credit: Dr Peter Ng

Hong Kong Underwater Photo Competition Winners 2016 Announced

The Hong Kong Underwater Photo and Video Competition 2016, jointly organised by the Agriculture, Fisheries and Conservation Department (AFCD) and Hong Kong Underwater Association, announced its winning entries.

The Hong Kong Underwater Photo and Video Competition, in its 5th year now, received 443 entries this year, featuring marine ecology, habitats and marine life in Hong Kong waters.

An AFCD spokesman said, “Entries over the years have showcased the beauty of marine life and habitats in Hong Kong waters, and have helped promote the conservation of the marine environment.”

The event comprised a photo competition and a video competition. In the photo competition the categories were Macros/Close-ups and Standard/Wide Angle. In addition to prizes for champions and runners-up in each group, there were Special Prizes for Junior Underwater Photographers presented by the judging panel to encourage less experienced underwater photographers to participate in the competition.

Please click the thumbnail images to enlarge.

The winning photos as well as the video entries can also be found on the AFCD Chinese page for the competition and the competitions Facebook page.