Alamea outbreak threatens Samoas marine eco system
By Cherelle Jackson
APIA - A massive outbreak in the population of alamea or Crown-of-Thorns (COTs) starfish (alamea, Acanthaster planci) in the oceans of Samoa is a cause for great concern.
This is according to Marine Conservation Officer for Conservation International (CI) Samoa office, Mr. Schannel van Dijken.
"The observed numbers of alamea on our reefs is a great threat. The alamea feeds voraciously on live coral and in outbreak numbers they are capable of killing 100’s of acres of coral reef.
A sudden loss of live coral can change the physical and biological character of the reef. This can lead to increased bio-erosion and loss of reef structure complexity which is in turn important for the fish communities present.
Dead corals and a reduction in reef habitat complexity lead to further reductions of associated fish species and abundances in which coastal communities rely heavily on either as a food source or as a form of income” van Dijken said.
The crown-of-thorns starfish is a notorious threat to the coral reef ecosystem according to marine scientists.
Although scientists from Stanford University say low numbers of this starfish can increase reef diversity, because it prefers to feed on fast growing Acropoid coral, this gives slower growing coral space to establish and grow and large numbers as observed in Samoa can destroy reefs.
In some instances overpopulation of alamea has resulted in widespread reef destruction in the Pacific as seen during 1978 and 1979 in American Samoa and more recently in many parts of the Great Barrier Reef, where 3 million Australian dollars is spent each year on trying to control Crown of thorn numbers.
In Samoa, the threat is serious and coral destruction has been noted along the Upolu south coast and in marine protected areas of the Aleipata and Safata districts.
CI reports that the south coast marine eco-system is still recovering from the impact of the tsunami. According to van Dijken this major disturbance has helped allow alamea numbers to explode as the fast regenerating coral species provide irresistible food for the fast growing starfish.
Anecdotal evidence suggest an increase in the numbers of alamea in all the no take zones of the Aleipata and Safata Marine protected areas, locals also reported that the outbreak seems worse.
Van Dijken says that once large numbers have been established they are very hard to control due to the reproductive biology of the alamea.
“Although why alamea outbreaks occur and not fully understood, reef disturbances, overfishing of large reef fish which naturally eat alamea, sedimentation of the coast from development, and increased freshwater input such as following heavy rains are some major factors that contribute to Crown of thorn outbreaks.”
The Marine Conservation Officer says heavy overfishing and unsustainable development practices can lead to increased starfish numbers.
In the past year, Conservation International has help support the Aleipata and Safata Marine Protected areas concentrate on efforts to eliminate the predator from the shores of Samoa.
An eight person team from CI, the Ministry Natural Resource and Environment and members of the community were deployed at Aleipata marine conservation area over 3 days last October to manually remove the predators.
"In one day we removed 237 alamea in three and half hours from the Aleipata MPA," van Dijken said.
During times of food shortage the crown-of-thorns can survive on energy reserves for over six months.
van Dijken says this persistence means community action is urgently required to remove the pests. "It's challenging, but it's needed," he said.
The Marine Conservation Officer suggests care must be taken when removing the alamea as the starfish have venomous sharp spines that can hurt if touched.
“The best practice is to remove them with a spear and containing them in a bucket while trying not to touch them at all, then bringing them ashore to bury,” van Dijken said.
In an effort to contain the spread of the predators CI funds coastal surveys and awareness and education programmes for coastal communities.
The projects are in partnership with the Ministry of Natural Resource and Environment with the cooperation from Aleipata and Safata Marine Protected Area trust and local community.