Icerber orders

[Lucacrebbe]

On Lakebtc I red  this:

Darkpool orders - if you are buying or selling a large number of coins, you may select this checkbox to make your trade order invisible in the orderbook to minimize the impact on the market. Darkpool orders will be charged a higher trading fee.

I was wondering if  the icerberg  orders impact the market and  the volume,  I mean if  even  they are  hide can they be seen by  an expert trader?  How?