Dead Fish Found Along Kwun Tong Promenade

Thousands of dead fish were found floating in the water along the Kwun Tong promenade over the weekend
(11-7-12/7/2015), releasing a strong stench that many passersby found unbearable.
The dead fish covered a two-kilometer stretch along the promenade, and it took the Marine Department seven hours to clean up about 2,000 kilos, Apple Daily reported.

Several species were identified, including tilapia, seabream, grey mullet and spotted silver scat.

Cheung Ma-shan, science manager at the Eco-Education and Resources Center, said the mass death could be due to the low oxygen content in the water caused by typhoon Linfa.

Chong Dee-hwa from the Ichthyological Society of Hong Kong said the typhoon could have stirred up mud and toxins from the bottom of the sea, thus affecting fish populations.

The Department of Environmental Protection was undertaking tests of water samples obtained in the vicinity.

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HKD 4.3M Grants Won for Tolo Harbor (吐露港) Biodiversity & Ecology Research

More than 25 local marine biologists have been awarded a grant that will enable them to study the marine biodiversity and ecology of the Tolo Harbour and channel.

Tolo Harbor is a semi-enclosed body of water in the northeast of Hong Kong linked to the sea only by the narrow Tolo Channel. The Tolo Channel and Harbor were infamous in the 1980’s for terrible water pollution, fould smells and red tides. A rapid expansion of urban areas on the firnge of Tolo Harbor with direct, untreated sewage discharges into the Harbor caused large scale eutrophication. The sewage outfalls provided nutrients feeding massive algal blooms which subsequently died and their decomposition by microorganisms used up so much oxygen that the water and sediment became anoxic, killing fish and many other marine organism (again feeding oxygen demand form decomposition) and causing foul smelling water. The problem was made much worse because Tolo Harbor is not very well flushed with new oxygenated water from the sea. It was eventually improved by providing proper modern sewage treatment and recognizing the particular vulnerablility of the area to eutrophication.

The HK$4.3 million will benefit the Joint University Consortium for Biodiversity, Ecology and Conservation of Marine Ecosystems and comes via the Environment and Conservation Fund (ECF). The ECF was established by the government in 1994 as part of its long-term commitment to environmental protection and conservation and received an injection of $5 billion in 2013, to serve as seed money generating an annual investment returns to support green projects and activities. The ECF has so far funded over 4,290 educational, research, and other projects and activities in relation to environmental and conservation matters.

Despite the funding being delayed for about two years, the proposal was approved last month and the 18-month project will commence later this year. The first stage of the two-phase study is aimed at finding the current ecological status of the area as well as the economic value of marine resources. The team will establish a comprehensive species database of the area. Kevin Ho King-yan, a senior research assistant at the School of Biological Sciences at the University of Hong Kong, said the proposal was aired at least two rounds of interviews, possibly because of the large amount of money required.

“Usually, project funding proposals to the conservation fund average around the hundred thousand mark, but this time it is in the millions,” he said. The announcement comes after an international conference, jointly organized by the Swire Institute of Marine Science and the University of Hong Kong School of Biological Sciences, kicked off at HKU yesterday.

More than 280 participants from 26 countries have come together for the four-day conference to discuss issues such as coastal development and marine conservation. More than 20 marine scientists from overseas and the mainland are attending. Organizing committee chairman Kenneth Leung Mei-yee said experts from across the globe need to work together to map out a plan to protect marine biodiversity. “We need experts from all different sectors to join hands together to uncover what we have and how we can protect them and how we can make sustainable use of these resources,” Leung said.

Note: The Hoi Ha Wan marine park – noted for its corals – is located at the seaward mouth of the Tolo Channel.

Source: The Standard 2nd June 2015

Human Error Kills 59 Fish at Ocean Park

In the early morning of the 3rd of July (2014) 59 fish were found dead at Ocean Parks aquarium,

including a breeding pair of bamboo sharks, two rays and some other fish .

The park said the event was caused by human error, and that the employees involved would receive disciplinary action and that procedures would be reviewed additional sensors installed. An inquiry found that the deaths were the result of a lack of oxygen in the water which lead to the fish suffocating. Normally procedures for tank maintenance allow staff to switch of the wave generator that oxygenates the water for up to 6 hours without causing harm to the fish. In this instance it was switched off for water treatment projects to be carried out, but staff failed to then properly restart it.

Ocean Park has not made a press release available.

Source: RTHK, 14/7/2014

Guns, Condoms and a Lot of Dead Fish – Pui O

A day outing to Pui O beach with the kids. Aside from perfectly new water pistols, a used condom and unstoppable amounts of plastic trash, trapped in the lagoon behind a sandbank at low tide, there were also at least a hundred dead fish including a large puffer fish and two edible species, the grey mullet (Mugil cephalus) and the conger eel (Muraenesox cinereus), though these examples most definitely we’re not edible.
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Red Tides, Fish Kills and iPhone Apps

Here are some images of some pretty right red tide patches. But what on earth is it that makes the water go red like this and is it dangerous?

red tide in DB
Floating patch of red tide in Discovery Bay 4/6/2014

Red tide is the collective name for phytoplankton blooms that tend to colour the water. Phytoplankton is made up of microscopic plants that drift through the sea. When conditions are right (mostly when there is nutrient-rich water and a stable water column) some species of these micro-algae form red tides. Depending on the pigments, the massive growth of algal cells may turn the water into pink, red, brown, reddish-brown, deep green or other colours.

"Pink" Red Tide on Tai Pak Beach
“Pink” Red Tide washing ashore on Tai Pak Beach in Discovery Bay 4/6/2014

 

Red tides are a relatively common sight in Hong Kong with 20-30 reports a year. The immediate reaction from most people is to think that they are the result of some terrible pollution. In fact the phytoplankton species are perfectly natural and normally occur in Hong Kong waters, but under certain conditions they can grow faster and form patches on the sea surface which we call ‘blooms’. Phytoplankton blooms by different species occur all over the world and are often seen by satellites with colour sensors.

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Bloom of the phytoplankton species Emiliania huxleyi in the English Channel as seen from space by a satellite. The light blue comes from the seawater and the white calcium shell of the algal species.

Some red tides produce natural toxins, and can cause depletion of dissolved oxygen or other harmful effects, and are generally described as harmful algal blooms (HAB). The most conspicuous effects of these kinds of red tides are the deaths of marine and coastal species of fish, birds, marine mammals, and other organisms. This happens either as a direct effect of the toxins produced or because of oxygen depletion (known as hypoxia) which happens when the algae die and bacteria consume all the oxygen in decomposing the dead algae.
Only some species involved in red tides however are toxin-producing and cause fish kills. The bioluminescing species Noctiluca scintillans which I wrote about in an earlier post, is not toxic but still can cause red tides.
For Hong Kong this is an economic concern because of the many fish farms and aquaculture areas. When a toxic red tide drifts into a fish farming zone only early warning will help the farmers avoid large economic losses from fish kills by temporarily evacuating their fish cages or transferring their fish to tanks.
The Agriculture, Fisheries & Conservation Department (AFCD) of Hong Kong runs a red tide monitoring network which relies partly on fish farmers and members of the public.  The AFCD follows up reports by taking samples from the red tides and identifying the contributing species under the microscope to determine the risk to aquaculturists and the public. The majority of the reports are caused by non-toxic species. If you would like to know more about the network, the AFCD now has a fantatsitc  app for iPhone and Android (pictured below) with weekly updates and the functionality to report red tide sightings (which I proudly did today) with this new app, including submitting  pictures. (I would also recommend some of the other Hong Kong apps for marine enthusiasts out there:  HK Geopark, Wetland Park, Reef Check, Red Tide Information Network and the WWF Seafood Guide).

 

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The AFCD’s “Red Tide” App for iPhone (also for Android). You can get weekly updates and also report red tide sightings. Available in Chinese (traditional and simpliefied) and English.

 

The AFCD started to record the occurrences of red tide since 1975. From 1975 to 2013, a total of 875 red tide incidents were recorded in Hong Kong waters. Amongst these incidents, only 27 were associated with fish kills.

77 algal species have formed red tides in Hong Kong, but majority of them are harmless. 19 of these species are considered harmful or toxic. Amongst these harmful/toxic algal species, only 5 of them caused fish kills and the other two caused contamination of shellfish by toxin in Hong Kong. The red tide associated fish kill events were mostly recorded in the 80’s and early 90’s.

So are there dangers to human health? If a red tide is identified as a harmful algal bloom (HAB) – then, yes, there is a risk:
The consumption of shellfish (e.g. mussels, clams) is one of the most common ways for algal toxins to impact human health. Each species has it’s own toxin so the health effects they cause are also varied. One example is Ciguatera fish poisoning. This type of fish poisoning is caused by eating fish that contain toxins produced by a the marine microalgae Gambierdiscus toxicus, which has been recorded in Hong Kong waters. Barracuda, black grouper,blackfin snapper, king mackerel, groupers and any large predatory fish can carryciguatoxins. People who haveciguatera may experience nausea, vomiting, and neurologic symptoms such as tingling fingers or toes. They also may find that cold things feel hot and hot things feel cold.Ciguatera has no cure. Symptoms usually go away in days or weeks but can last for years. People who haveciguateracan be treated for their symptoms. In Hong Kong with its rapacious appetite for seafood, ciguatera fish poisoning occurs quite frequently. For example, in 2004 it made up 7.9% of all food poisoning cases recorded that year. In June 2013, fourteen men and five women, aged 23 to 71, fell ill with ciguatera poisoning after eating coral reef fish at a restaurant in Sok Kwu Wan (Lamma Island). The fish in this case actually came from the Pratas/Dongsha Islands out in the South China Sea. Ciguatoxin’s is very stable, so cooking, drying or refrigerating fish will not destroy the poison. There is also no effective way to test fish for ciguatoxin, yet. If you want to play it safe avoid large predatory fish like tuna, grouper and others alltogether (they are mostly overfished already, especially blue-fin tuna, so you would be doing the planet a big favor).

So eating shellfish or fish which has been exposed to HABs is the main danger to humans. There are instances of skin irritations and breathing difficulties after direct human exposure to HABs but these are rarer and not as well understood. So to be absolutely safe, I would advise you to avoid contact with red tides – no swimming in, diving under or touching them!

Toxic Algae and Man-Sized Jellyfish

Once a swampy backwater of fewer than 20 million people, the Pearl River Delta—the southern swath of mainland China above Hong Kong—now has three times that population. Tens of millions more humans in the Pearl River Delta means many more toilets a-flush, pumping a steady gush of human waste into the South China Sea.
Read the full story at Quartz

SCMP: Mainland sewage fuelling Hong Kong’s ‘red tides’

According to the SCMP, sewage from the mainland is fuelling an increase of harmful algal blooms – known as red tides – in Hong Kong waters.

Professor Ho Kin-chung, dean of the Open University’s school of science and technology and an expert on algae, told the SCMP the red tides were “fed” by nutrients flowing in from mainland waters to the east and west of Hong Kong.

“The economic boom across the border leads to more sewage discharge into the sea and rivers, and in the right seasons [the nutrients] come down to us. So this is no longer a local phenomenon but a regional one,” Ho said.

Within the last fortnight brown algae been spotted across the territory – off Lamma Island, Cheung Chau, Lantau and within Victoria Harbour.

Agriculture, Fisheries and Conservation Department staff said they had spotted red tides at fish culture zones within Tolo Harbour, Sha Tau Kok and Tai Mei Tuk, while a member of the public reported another at Pak Sha Wan in Sai Kung.

Most algae absorb nutrients such as phosphates or nitrates that are commonly found in cities’ wastewater. At the right temperature, well-fed algae will proliferate in a short period of time.

Ho said Hong Kong was sandwiched by the Pearl River in the west and Mirs Bay in the east and these were the two key origins of red tides in local waters.

As a result, Tuen Mun, Lantau, Tolo Harbour and Sai Kung were becoming increasingly prone to the phenomenon.

Recent reports of large amounts of seaweed being washed onto beaches in South Lantau should not be confused with red tides. Red tides are composed of free-floating (planktonic) algae, seaweed however are larger marine plants normally growing attached to the seabed, reefs or rocks.

A spokeswoman for the Agriculture, Fisheries and Conservation Department said it would announce today whether tests had found the algae off Lamma Island to be toxic.

Four red tides were also spotted in Hong Kong waters last week.
Three red tides at fish culture zones within Tolo Harbour, Sha Tau Kok fish culture zone and Tai Mei Tuk were observed by staff members of the Agriculture, Fisheries and Conservation Department (AFCD) during April 8 to 10. Another red tide was spotted on April 9 by a member of the public at Pak Sha Wan, Sai Kung.

None of the red tides were associated with the death of fish in these occurrences.  “The red tides at fish culture zones within Tolo Harbour and Tai Mei Tuk were formed by Gonyaulax polygramma, Prorocentrum minimum and Heterosigma akashiwo. The one at Pak Sha Wan, Sai Kung, was formed by Gonyaulax polygramma whereas the one at Sha Tau Kok fish culture zone was formed by Heterosigma akashiwo and Prorocentrum minimum. All the above algal blooms are commonly found in Hong Kong waters. Gonyaulax polygramma and Heterosigma akashiwo are non-toxic. Studies have shown that Prorocentrum minimum may produce toxin, but no such reports or associated fish kills have been recorded in Hong Kong,” a spokesman for the working group said.

Red tides are a natural phenomenon. The AFCD’s phytoplankton monitoring programme will continue monitoring red tide occurrences to minimise the impact on the mariculture industry and the public.

In 1998, a red tide killed 80 per cent of the stock at Hong Kong fish farms.

 Source: SCMP 17/04/2014 and AFCD Press Release 11/04/2014