[Coral-List] sea urchin removal to prevent bioerosion

Bill Allison allison.billiam at gmail.com
Wed Feb 17 11:53:49 EST 2010

There was a effort made to remove control the abundance of
Strongylocentrotus droebachiensis on off Nova Scotia in the early 1980s
followed by a mass mortality in about 1983 that may be instructive. Try
Marine Biology (Mann, Wharton, Scheiberling, others). If I am not mistaken a
retrospective paper on the removal exercise and its conceptual
rationalization concluded that it was misconceived.

On Wed, Feb 17, 2010 at 3:01 AM, Clement Dumont <cdumont at hku.hk> wrote:

> Dear all,
> thank you for all the comprehensive replies from which I learned a lot. My
> initial question, however, remained unanswered. Does anybody is aware of
> report/publication of such removal practice of grazers to protect/restore
> coral reefs (i.e. removal program similar to the crown-of thorns)?
>  I have also a project in Malaysia where the Marine Park rangers remove
> every year the sea star Acanthaster planci in an attempt to prevent
> population outbreaks. However, when I found similar densities of sea stars
> at the sites where removal occur with sites where no sea stars are
> collected. Unthinking removal programs are generally unsuccessful and can
> even further damage the corals (e.g. Japan sea star removal).
> Best wishes,
> Clement
> ---------
> Date: Thu, 11 Feb 2010 08:54:02 +0800
> From: Clement Dumont <cdumont at hku.hk>
> Subject: [Coral-List] sea urchin removal to prevent bioerosion
> To: "coral-list at coral.aoml.noaa.gov" <coral-list at coral.aoml.noaa.gov>
> Message-ID:
>        <A079DF1679D36540A0B97A14317E122A12B13FA575 at MAIL.hkucc-com.hku.hk>
> Content-Type: text/plain; charset="us-ascii"
> 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/ <http://web.hku.hk/%7Ecdumont/>
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Reality, as usual, beats fiction out of sight.
Conrad, 1915

"Reality" is a dangerous word that should always be incarcerated in
quotation marks.

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