Impacts of Colloidal Chalk

[Simon Wilson]

Dear Coral People

Dredging works on a fossil reef in Oman have hit a deposit of what the
geotechnical engineers are calling 'colloidal chalk'.  The site is in about
6m of water and only a few meters from the surface of the substrate, in an
area with some important Acropora dominated reefs.  About 8km away is
another area of pristeen monospecific reef composed of Pocillopora
damicornis.

I have two questions:

Firstly, is anyone away of the impacts of fine chalky sediment on corals or
any references in the literature which may shed light on the potential
impacts, and  secondly, does anyone know how such deposits are formed so
that it may be possible to predict if there are more deposits in the area ?

Thanking you for your time to reply in advance.

Simon Wilson & Robert Baldwin 
e-mail 106422.2221 at compuserve.com  or wosoman at gto.net.om