22 May 2009

Scary Aliens in Singapore

Today, the ever provocative and thought-provoking Prof Peter Ng gave a talk about alien introductions in our wild places.
In celebration of The International Day for Biological Diversity, he gave a talk entitled "Crossing the Line - Illegal and Unwanted Aliens in Singapore". (And I must say, he looked particularly handsome today).

While I thought I knew something of the issues, I was quite dismayed to learn more about their true extent and scope.

Jun was live twittering the talk! A great first effort, check it out on her ashira blog. Her feat was also posted on the biodiversity crew @ nus blog.

Here's some of the issues that caught my thoughts, not necessarily in the sequence that Prof Peter presented them.
Prof Peter highlights that much of the wildlife that ordinary people commonly encounter in Singapore are actually aliens. Animals we think as typical Singaporeans are not.
I didn't even know the House sparrow is an introduced bird! Oh dear, it's such a cute little thing too and seems perfectly harmless.

Alien species are introduced to new habitats where they did not originally naturally occur. And it's all the fault of the humans.
Many animals have long accompanied humans as we travelled into new lands, some wanted and others unwanted.

The Tilapia is so successful an alien species that many people think they are native to Singapore (originally from Africa, it was brought to Java as a potential food fish, and then to Singapore by the Japanese). These fishes are out-competing our native fishes and aquatic wildlife.The giant snail that is commonly seen is another alien. Elsewhere, they are causing much damage to agricultural crops as they are voracious feeders.

In his usual humorous turns of phrases, Prof Peter shares one 'positive' effect of aliens.
The introduced snakeheads are eating the introduced tilapias! Haha. Unfortunately, it is impossible to remove the snakeheads (or tilapia or any other introduced animal). He shared how efforts in the US to remove snakeheads were unsuccessful despite extreme measures.

The humungous American bullfrog is another introduced species that may even eat our native frogs. These bullfrogs are often released on purpose for religious reasons, as part of a ritual to gain merit.
A water snail that lays bright pink eggs is very commonly seen in our waterways. It is an alien and is outcompeting our native water snails.

Another surprise alien is the guppy!
Even the guppies in our 'longkang' (drains) are exotics. These fishes are originally from Trinidad and Tabago and were named after the Reverend Guppy who discovered and described the fish. Being pretty to look at, hardy and prolific in reproduction, these fishes soon were spread to other parts of the world via the pet trade.

Indeed, the pet trade is one of the avenues of introduced aliens.
And Singapore being the centre of aquarium trade, is vulnerable to introductions of all kinds of exotic aquatic life.

For example, there are now fresh water stingrays found in some of our water bodies. Probably via the aquarium trade.
Prof Peter says he warned about these some years ago, and nothing was done about them then. Now, these dangerous animals make recreation in our water bodies hazardous. There have recently also been sightings of electric eels, electric catfish and other dangerous introduced fishes. While other introduced fishes stir up the sediments and destroy the habitats.

The Red-eared slider is a cute turtle when it's tiny.
But as Prof says, it gets ugly as it gets older. And pet owners often 'humanely' dump adults in our ponds and reservoirs. Here, they disturb the natural balance and compete with our native turtles.

Despite these dangers, hobbyists continue to pressure to be allowed to bring in exotics such as these: piranhas, the poison arrow frog and ferrets! (What are they thinking...I'm saying to myself...ferrets?!!)
As Prof Peter says, it's hard to trust that pet owners will not allow these animals to escape into our wild places.

Sometimes, animals are introduced for the most altruistic reasons. He shared how earthworms were introduced as part of a scheme on composting and recycling household food waste.
As a result of this scheme, a study was done on our earthworms and it was found that out of the 15 species found here, 12 were aliens! Only 3 were native and these were confined to our nature reserves. One species of introduced worm accounted for 70% our worms!

Being at the centre of vast trade routes, Singapore is also vulnerable to introduced species hoping off transport.
Ballast water carried in ocean-crossing ships are full of marinelife small and big, young and adult that get dumped into places where they do not naturally occur.
It is very difficult to control the dumping of ballast water.

Prof Peter is THE crab person so he is really excited about crabs.
He shared how he found crabs and crustaceans from vastly distant areas by examining the bits that were cleaned off an oil rig being maintained in Singapore. The animals live in the growing ecosystems of encrusting marine life that settles on any hard surface that remains submerged in the sea. The oil rig picks up all kinds of animals as it is moved from place to place. And finally, all these animals end up in Singapore waters when the rig is cleaned.

Prof Peter also shared how an introduced crab that was devastating the clam industry in New Zealand was traced to Singapore. There was the threat of a lawsuit. The threat passed us when it was further discovered that the original source of this temperate climate crab was China.

Singapore is also a hub for land transport which is responsible for the introduction of the changeable lizard (the brown on the left), originally from Thailand.
Prof Peter shared how a study many years ago found them concentrated near our railway station. They have since spread out throughout the island and are outcompeting our more elegant green crested lizard (on the right).

Another consequence of alien species is that they may introduce dangerous viruses and parasites which can cause health problems in humans and our native wildlife.

Other issues include: introduced plants, problems with people who think that more species=more biodiversity even though the species are not native, the problem of arrowanas which are alien species in our waters but internationally protected so how do we get rid of them? and lots more complex and rather sad issues.

Prof says "sometimes it takes a disaster to raise awareness of the issue" and he shared about the disaster that is the brown snake in Guam. It would be a sad day if the same fate befell our native animals. Shudder.

The problem of preventing introduction of alien species is difficult as many parties are involved.
There are issues of what should be defined as 'native species'. And also the need to raise awareness of the potential costs and impact of introduced species.

The talk was followed by a very lively Q&A discussion of how making it economically profitable to remove aliens may actually encourage people to keep bringing them in; the need to raise awareness of the issues with the young and among decision makers; the criteria used to determine how dangerous an introduced species can be (short lifespan, high reproductive rate, hardiness, etc); and how the macaques are a problem not because they are introduced -- they are native -- but because humans feed them; and how increasing connectivity of our fragmented habitats may exacerbate the problem of alien introductions.

Just before the talk, Lena Chan shared some of the work done to raise awareness about biodiversity.
One of the activities was Green Wave where all over the world at 10am today, trees were planted.

There's also a great series of posters by Wei Ling of Biodiversity Centre at the entrance to the talk.
Tomorrow is Envirofest 2009 where the celebration of biodiversity continues! Do drop by to have fun and learn about our wildlife. Envirofest is at HDB Hub 11am-8pm Saturday and Sunday. More about Envirofest 2009.

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