DLNR press release (17 August 2010) - The use of native collector urchins to manage invasive seaweed on a patch reef in Kaneohe Bay - HEAR
Native collector urchins placed on the patch reef were kept to half of the reef where they grazed invasive algae.  On the half of the reef without sea urchins, invasive algae proliferated.

Native collector urchins placed on the patch reef were kept to half of the reef where they grazed invasive algae. On the half of the reef without sea urchins, invasive algae proliferated.

Urchinshalfpatchreef