Thanks to the contact from two SFN members...the first asked me more details...yes they are a plague in that there exists too many of them and are remarkable in their rapid populating as something like 20-30 the square meter...they over-ride habitat to other creatures that have been observed to live there and the urchins are making barrens of the sea bed by predation on the prominent algae.
There have been scientific studies and certainly I have acquired much information though little response from the sites and Univs where from the studies were made.
The known predators of the Diadema antillarium or long spine black sea urchin are themselves in rare comodity...very rare...the Spiney Sea Star (Marthasterias glacialis) and the Thorney Sea Star ( or multiarm) (Coscinasterias tenuispina). These stars have such infrequency that it is difficult to say whether or not they themselves might be an endangered species....the Triggerfish such as the Blue/Scrawled (Aluterus scriptus) and the Ocean (Canthidermis sufflamen) plus the Grey(Balistes capriscus) are equally predators of said urchin but themselves in very short order due to over fishing as an ecellent eating fish.
Thus we have a carpeted floor of black urchins with the local divers doing the humanly obvious of breaking to feed the Chromis and Wrasse that appreciate the contents...this is an act to prevent the perpetual problem of divers geting pierced in all imaginable parts of the body.
My simple point of enquiry is of any further criteria on elimination of said species(knowing of the reverse problems in the Keys and Carib islands) or if there is a useful commercial proposition here to be advantaged.
Scientists normally count measure and weigh to get statistics, but site counts are far more indicative of the problem...the Thorny stars in the second comment might find a useful diet here but presumably the temperature of water would perhaps not let them reisde so as in Aussie waters.Equally if the Thornies procreate with such rapidity we'd suffer the replacementof the same problem...so far so good and any more thoughts out there....will post this also on a biology sitethread...thankyou for the contacts so far.