Northern Pacific Sea
Northern Pacific Sea star (Asterias amurensis)
KINGDOM: Animalia
PYLUM: Echinodermata
CLASS: Asteroidea
ORDER: Forcipulatida
SUBORDER: Asteriadina
FAMILY: Asteriidae
GENUS: Asterias
SPECIES: A. amurensis
Binomial Name: Asterias amurensis
Asterias amurensis, which is commonly known as the “Northern Pacific Sea star”, is an introduced species in Australia. The Northern Pacific Sea star is native to the coasts of Northern China, North Korea, South Korea, Russia and Japan. Distribution of this species into other countries has also increased (such as Australia). The Northern Pacific Sea star populations are commonly in shipping ports and shipping routes, the Sea star has been most likely introduced by the transport of free-swimming larvae in ballast water for ships. The ships that have suck themselves in the ballast water containing Sea star larvae, like a docking port such as one in Japan, and let it out in a port in Tasmania, the larvae come out with the ballast water therefore infecting Tasmania's Derwent River Ecosystem.
The Northern Pacific Sea star is easily identifiable compared to the native Sea star Coscinasterias muricata and also Uniophora granifera. The Northern Pacific Sea star has 5 arms with pointed upturned tips. They have 5 arms with pointed tips which are upturned at the end, are mainly yellow but may have purple detail and are covered in many small spines with jagged ends that are arranged irregularly long arms.
Northern Pacific Sea star Asterias amurensis (CRIMP - CSIRO Marine Research)
Northern Pacific Sea star Native Sea star Native Sea star Asterias amurensis Coscinasterias muricate Uniophora granifera (Photograph by CRIMP - (Photograph by Terence Bogue (Photograph by Terence Bouge CSIRO Marine Research) Tasmanian Museum and Art Gallery) Tasmanian Museum and Art Gallery)
The Northern Pacific Sea star is able to change colours to adapt to different climates and also blend in with its surroundings.
As you are able to see in the above pictures The Northern Pacific Sea star is easily identifiable to the other native species.
In Australia, the Northern Pacific Sea star starts spawning from July to October at temperatures of 10° C to 12° C. Fertilized eggs develop into free-swimming larvae that live in the water for around 90 days before settling and developing into juvenile Sea stars. In one year the northern Pacific Sea star is capable of increasing its body diameter by 8 cm. When the Northern Pacific Sea star is fully grown the Sea star is able to live for a maximum of 5 years. During its life it is able to reach sizes of up to 40cm to 50 cm in body diameter. In general, The Northern Pacific Sea stars are sensitive to ultra salty conditions, and are unlikely to be found in places of high salinity. In Japan, the Sea stars numbers can increase and reach large proportions for two to three years; large outbreaks of the species have been found to occur in three or ten year cycles.
The North Pacific Seastar is native to the coasts of northern China, Korea, Russia and Japan, The Northern Pacific Sea star lives in waters between 7 °C and 22 °C. It lives in mainly shallow water, but can also be found at deeps as deep as 200 meters. It is hardly ever found on reefs or high wave areas such as surf areas. Instead its natural habitat is sitting on mud, sand and even pebbles.
In Tasmania, due to the outbreak of these Sea stars, removal days have been organized, where volunteers workers of environmental groups get together to try and physically remove all of them from the area. They try to dispose of as many as. Efforts of this kind in 1993 resulted in the collection of more than 30,000 Sea stars; these were removed from the Derwent River ecosystem. During the very first attempts to remove the Sea star from Tasmania, many of the Sea stars that were caught were cut up and thrown back into the sea. Unfortunately, each part that was thrown back was able to regenerate and grow a new Sea star as long as it had part of the main body available; this is usually commonly named as the central disc.
The Northern Pacific Sea star poisons are not instantly recognizable and in the ocean, could damage many other natural ecosystems.
Also, the amount of chemicals needed to poison the Northern Pacific Sea stars in river systems would be stupid, and very impractical.
In Australia, Northern Pacific Sea stars don't have any pathogens, though in Japan, Northern Pacific Sea stars are attacked by a unique multi-celled animal called an Orchitophrya. The Orchitophrya invades the Sea stars testicles and kills sperm and de-sperms the Sea star. However scientists later discovered that Orchitophrya doesn't usually invade all of the 10 of the Sea star testicles and doesn't have the effect hoped for by them.
The Northern Pacific Sea star has also been found in Port Phillip Bay in Victoria, and also the Derwent River in Tasmania for quite a few years now.
The North Pacific Sea star has also moved itself inland into the Maribyrnong River system, being able to reach as far inland as Essendon in Melbourne. The Maribyrnong is a salty river (previously known as Saltwater River), but finding the sea star this far inland is very unique.
The Northern Pacific Sea star is usually found along the Eastern Coast of Tasmania, usually at a fairly close distance to the shore. The highest density of Northern Pacific Sea star populations are found from Banks Strait in the north to Recherche Bay in the south. The highest population densities are found in the Derwent River, in Hobart.
To further reduce the risk of spreading the Northern Pacific Sea star marine pest, the Northern Pacific Sea star has been listed as a harmful species under the Living Marine Resources Management Act [of] 1995. To collect and have this species requires a special permit which you are able to apply for from the Department of Primary Industries and Water by calling 6233 6208 or applying at any Service Tasmania store state wide.
Community divers pulled 30,000 of Northern Pacific Sea stars from the Derwent River in 1993, that hardly hurt the numbers of the population.
To protect commercial shellfish rent, a company has especially designed traps that have being made in Tasmania, these are being used to try and cut populations to a minimum.
The Northern Pacific Sea star traps are very similar to a rock lobster trap, they have been baited with fish flathead, travella and other common species. But these specially made traps cannot catch all of the Northern Pacific Sea stars in Tasmania's waters.
Dredging could collect more of the Northern Pacific Sea stars at once, but dredging would upset the natural marine plants and animals and ecosystems in that area. Dredging would also disturb the heavy metals in the bottom sediments.
But one of the main problems would be disposing of the extremely large numbers of Northern Pacific Sea star remains would also be a huge problem. The Northern Pacific Sea stars can be composted and used as garden mulch put into fertilizer, but 30 million of Northern Pacific Sea stars leftovers would be stretching the limits to even the largest compost facility in the state. So, collecting the Northern Pacific Sea stars could be useful in responsible areas like marine farms such as the Woodridge centre or even the CSIRO. Or even in the marine reserves throughout the state, but having said this it requires a permit. This is probably just not as practical or possible for all of the Northern Pacific Sea stars in the Tasmanian waters.
In the near future, molecular biology technology could be connected to attack the Northern Pacific Sea stars. Scientists could insert or change genes in The Northern Pacific Sea stars which would castrate them or kill their young, therefore slowing down their breeding patterns. The genes could be given to them in a bait form, or even by a parasite.
But for now, it is important to gain much knowledge as possible about The Northern Pacific Sea star, and how it can easily adopt to the Australian waters and its ecosystems. Scientists also want to learn more about how its able to feed itself, reproduce with its own breed and find out if its able to breed with other types of Sea stars. They would also like to learn more about its predators and its movements.
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