The problem is most divers can't tell the difference between live and dead coral. It is sad but true, flame me if you want but what I see is the majority of recreational divers looking at the pretty colors and not having a clue...of course this isnt the case for all but for a lot of divers it is. I think most of the divers I have seen dive in the Caribbean can't tell the me what type of coral they saw, a lot would say sea fans, brain corals and some other things lol. Most cant tell Acropora cervicornis from A. palmata even though they are very distinct acros. If divers can't tell the difference between rock, and live coral, how can someone expect them to know what it is they are holding. I think this is why most dive ops just go with touch nothing approach.
I dive with thin gloves, I do a lot of diving in the Caribbean and find most of the mooring lines encrusted with things (hydroids, ec.) I would rather not sting my hands on during safety stops. I don't use them for warmth. I also do some reef clean up dives, where we pull old anchor lines wrapping around coral, trash and other crap that's damaging reefs off the reef. I need gloves to do that. I would love to go to all them reefs and collect the trash and make a big pile on the beach, where the tourist could see first hand what they are doing to the reefs, but that wouldn't go over to well. Anyhow that's another thread....
I did the Hanauma Bay in Oahu snorkel thing last year when I was there visiting my sister. I believe thats where it was anyhow. You had to watch some video that kept going over dont stand on the reef....then you walk out side and down to the beach. What do you see but dozens of people standing on the reef...
FWIW, I grow SPS corals, LPS corals, soft corals, etc for trade/sale. I can take colony's of SPS coral from my aquarium (which were all bought tank raised as small 1" frags), snap them into pieces by hand. Super glue them to mounts and regrow the frags with out killing the coral. In general though on the reef, its breaking the tissue of the coral when you hold on, that could open it up to infection. Much like getting a cut, opening your skin to infection. Also holding onto "dead coral" can be just as bad of a practice because you could be killing much more sensitive recently settled coral larvae. Although if you must hold on, grabbing rock is better then coral, it is still damaging. There has been some research although none that I know of thats difinative that suggest the presence of a microbial film is a pre-requisite for the response to the inductive cue for coral larvae settlement. Destroying that by holding dead rock could cause an area to not be colonized by new coral.
Just as bad, or worse in the Caribbean I would say is boaters anchoring on the reef. I watch from my house boat renter after boat renter drop anchor right on the reef, if they hook in it is usually at the expense of a large coral head that they in turn flip and destroy when they pull up the next morning. Even worse is as they sit there overnight their chain and line drags back and forth ripping up the reef. I go divng the next day and will find several small coral head ripped loose flipped upside down.
Like my Dad always says to me, for them it is paradise for a day, and if the reefs die out and the the beauty goes away they will find a new area to go. A lot of the same boaters are the one drinking all night, tossing beer cans/bottles in the water. Losing towels overboard that sink and get wrapped all over the reef etc...
Sorry for the rant...what do I know
I watched a single head of Acropora palmata grow from a small settled coral over a 6 year period, from tiny to a nice size colony. A dingy from one of the rented sailboats hit it with its prop one day smashing it to a bunch of chuncks. All the chunks succumbed to rapid tissue necrosis....6 years of growth gone to one careless boater.