A large number of reefs within the inner granitic islands of the archipelago of Seychelles could be entirely lost, unless concerted action is taken soon to control crown of thorns, warns Dr. Udo Englhardt, the expert on on the management of crown of thorns in a presentation of his most recent findings. Dr Udo Englhardt, believes this outbreak of the deadly starfish is due to increasing levels of human development in the Seychelles coupled with rising sea temperatures. Dr. Engelhardt has conducted this research as part of their ‘Mainstreaming Biosecurity’ project organised by the UNDP and Global Environment Facility (GEF) in conjunction with the government of Seychelles. The outbreak which was in the north western areas of Mahé two months ago, has now spread further down the western coastline as the starfish continue to spawn. The starfish can be seen on reefs between five and 25 metres deep and are not commonly found in shallow waters. It preys on strong hard coral polyps and is named crown of thorns as its upper surface is covered with thorn like spikes.
The crown of thorns starfish, one of the largest in the world, occurs at tropical and subtropical latitudes and have been found from the Red sea, across the Indian Ocean to the Pacific. This venomous starfish has been found in Seychelles as early as the 1960s in small numbers and an extensive eradication programme was conducted in 1997. During the 1998-99 El Nino coral bleaching, the crown of thorns died off too. However, they began to re-emerge in 2001-2003 and have now bounced back in alarming numbers. This April, a coral reef survey by Dr Engelhardt found that numbers of Crown of thorns in the reefs were 20 to 30 times greater than sustainable levels. He also found that there were at least three generations present, including a substantial number of juveniles in the under reef strata – a good predictor of future outbreaks reports the Seychelles news agency.