[Coral-List] sea urchin removal to prevent bioerosion

[Clement Dumont]

Dear all,
the Hong Kong government took the initiative (based on brief observations) to remove every year thousands of the sea urchin Diadema setosum and the corallivore snail Drupella sp. to prevent the excessive bioerosion of corals (but no studies have been conducted). Being really surprised by this initiative, I started a cage experiment with different densities of urchin to examine whether Diadema is the major factor contributing to bioerosion. With no much surprise (the experiment is still running), we have a higher recruitment of macroalgae and also higher sedimentation on corals non-exposed to sea urchin grazing and even with high densities densities of urchins, still no sign of bioerosion. Hong Kong waters are highly polluted and the nutrient enrichment and high sedimentation may rather be the main causes of corals degradation.
I am therefore curious whether such sea urchin removal practice (not on a fishery purpose) is/has been conducted elsewhere to prevent bioerosion of corals.

Thanks,
Clement

----
Clement Dumont
Research Assistant Professor
The Swire Institute of Marine Science
& The Division of Ecology & Biodiversity
The School of Biological Sciences
The University of Hong Kong
Pokfulam, Hong Kong, PR China 

Phone: (852) 51 99 1730
Webpage: http://web.hku.hk/~cdumont/