Invasive starfish contribute to destruction of the Great Barrier reef.

So we all knew that coral reefs are pretty endangered at the minute but in research released today another cause has been identified. Along with changing global sea temperatures & storms, Invasive species have greatly contributed in the destruction of coral reefs.

This destruction has now amounted to an astonishing 50% reduction in coral on the great barrier reef, one of the most complex and delicate marine ecosystems in existence. Whilst 48% of this destruction can be attributed to storms a continuous problem which is tricky to solve, a further 42% is blamed upon Invasive starfish species.

Crown of thorns starfish

Species such as the Crown of thorns Starfish (Ancanthaster Planci)  and the Northern Pacific Seastar (Asterias Amurensis)  HAve become new predators in the Great barrier reef and are slowly but surely eatinghteir way along the reef.

These species were traditionally confined to coastal areas, avoiding the vast expanses and great depths of the open oceans but Shipping has provided an opportunity for these species to spread their larvae wide and far and start new populations on coral reefs.

This has occurred by ships storing large volumes of sea water as ballast for long voyages to help stabilise the craft which is then jettisoned at the final destination.

The released water with larvae has hit the rich warm bed of the reef and these invasive species begin to take hold. With no natural predators they are free to go grow into large booming, plague-like populations eating as they go.

A particularly damaging effect is the lack of defences any natural prey has in this habitat. P[re-existing Starfish have evolved alongside prey such as shellfish and Bivalves which has enabled an arms race between predator and prey over the millenia.

These creatures however are ill-equipped when faced with a new predator and find themselves easily overcome. as many of these species serve to filter the water and regulate the reef ecosystem this takes out a vital component and further endangers the habitat.

In order to combat the spread of starfish-  the Australian authorities have invested $50m AUD in the hope of finding a weakness in teh life-cycle of the starfish. By their calculations if we could negate the problem they bring we could get teh reef growing at 0.89% p/a which though small would have a massive impact eventually.

This also serves as a poignant reminder of the complexity of ecosystems and why we must monitor changes in populations as, if this problem had gone unnoticed it could have affected the reef as a whole a unique habitat that supports well over 20,000 species.

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