Sea Urchin Counter plague

[ecodiver]

I have just arrived on SFN and would like to open with those related to the problem of the Diadema antillarium plague that has so much effect on the marine world of the Canary Islands...this counter plague is of course the inundation of Diadema and not a plague upon it...

 

As a marine ecologist and scuba instructor the factor of Diadema plays a vived impression on visiting divers and causes great ecological stress although at the same time there are intersting symbiotic relations with other species...what is interesting for me is any opinion regarding the best or preferred way to dismantle some 20-30 Diadema per square meter or if there is a useful way to enter into a commercial proposition of collection for human consumption...thus this post is to open a dialogue if possible.

 

In closing I must confirm that I am not a marine biologist and my interests are much more directed to the education of ordinary people/divers to appreciate the various marine environments but at the same time find solutions to problems that local govt and such scientific institutions that are not as yet dealing with this raging problem other than to seek european funds to set up cosy study programmes for the next ten years..if I am cynical at 57 let it not surprise anyone because I have over 40 years of experience of this environment...thus your input would be appreciated...Thankyou

[Airmid]

Could you tell us a bit more about the situation? Do these sea urchins represent a problem? I guess so, because you describe them as a "plague". But simply having a lot of these animals around doesn't necessarily mean that there is a problem. So, can you give us some details about what the problem is about?

 

I did a little searching myself, and found with the following information:

The long-spined black sea urchin.

Algal cover and sea urchin distribution at Madeira.

These gave me a little background on the sea urchins, but they didn't tell me what the problem was. So I'd appreciate it if you can help us out.

 

Airmid.

[Icemelt]

Hey Ecodiver

I think I can understand your situation, although until now I wasn't aware of the problem in the Canaries.

I've spent the past 15 years diving in the Red Sea, amongst other places, where we experience similar problems with the crown of thorns species.

Every five years or so a plague of these thorny creatures come marching up from the deep at night, gobbling up all the coral as they overwhelm the reefs.

During these periods, the more experienced divers club together to try to preserve the best dive sites.

Armed rather primitively with a 1m long metal prong with a hook on the end and a torch strapped to the other, plus a large canvas sack, we patrol the reefs during the early evenings and hook these nasty predators from the centre, placing them in the bag.

When catching them, it’s important not to allow them to break up since they can fragment very easily, with each fragment eventually turning into another complete crown of thorns !

There are literally thousands and thousands of them during these periods and it takes an experienced diver 15 mins or so to fill the bag with 0.5m dia crown of thorns at the rate of about 1 or 2 per minute. Once caught, since they are primarily made of water, as you might imagine, getting the sacks out of the water poses quite a challenge.

The following day the marine biologists turn up to count and size them, presumably creating some sort of record and statistic.

I really can’t imagine them being of any use to humans unless they harbour some fancy chemicals that could be used in the pharmaceutical industry.

I certainly wouldn’t want to eat one.

They smell positively horrible within a few hours of being landed !

More of my pics at http://www.scubastuff.net

[ecodiver]

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.