touching marine life

[mrv]

recently i had the pleasure of serving as a guide to a blind diver. yup. all those thoughts that are probably going through your mind went through mine. why? how? touch!? isn't that harmful to the coral and sponges?

the experience, however, turned out to be one of the most rewarding i've had as a dive instructor and liveaboard staff. i got to enjoy diving in a completely new...light.

i must admit that as wonderful as my experience was, i am still uncomfortable with the fact that the only way for a blind diver to get the most out of the dive is to touch. and i would like to ask some help finding scientific data on how much harm is actually done to sponges and coral when these are touched.

i am well aware of the proper diving protocol. i've been a guardian of the 'no touch' policy for quite a while as a dive professional and liveaboard staff. i've even had to 'correct' divers' habits of grabbing coral as they are taking some video or photos or being careless with the movements of their fins. what i would like to find out is precise, scientific data on how much harm is brought about by our touch to corals and sponges. i don't think the 'no touch' should be changed for the general diver population. however, i would like to be better informed next time i have the opportunity to dive with a blind diver. i would appreciate any info you could send my way.

thanks,
v.

 

[archman]

what i would like to find out is precise, scientific data on how much harm is brought about by our touch to corals and sponges.

Corals secrete mucous to protect themselves and aid in feeding. Contact (or even water movement) wears down or even strips this layer. Healthy corals (especially acroporid elkorn/staghorn types) can re-secrete fairly rapidly, provided the wearing agents are not unusually persistent. Rough contact with certain corals can abrade and damage polyps.

There seem to be a lot more waterborne diseases affecting corals now. One of their primary entrance vectors is through damaged tissues. Even more reason to leave the things alone. With my coral reef classes, I never allow anyone to touch hard corals. And on the rare occasions when I do it myself, contact is extremely light.

Gorgonian "soft" corals can be safely handled by divers that are careful. They also secrete mucus, so you should stay away from the polyps. I train my students to touch gorgonians only at the branch bases and holdfasts. The tissues there are pretty tough. Feels like velvet in most species.

Sponges don't secrete epidermal mucus (to my knowledge). You can poke and prod them all you want... the greater danger is to the diver getting spicules stuck in their fingers, and making friends with fire worms, mantis shrimps, and other "fun" pals.

You can also touch a lot of tunicates without causing them much distress. Their tunicin outer layer is usually very thick and tough.

The "no touch" policy seen on a lot of dive ops and marine parks is instituted mainly for mainstream recreational divers in mind. It's a good policy. I doubt a blind diver would be granted special dispensation to touch things in a regulated zone, however. Quite frankly I'm surprised that blind folks are permitted to dive in open water. I do not see how they can possess situational awareness.

 

[mrv]

Corals secrete mucous to protect themselves and aid in feeding. Contact (or even water movement) wears down or even strips this layer. Healthy corals (especially acroporid elkorn/staghorn types) can re-secrete fairly rapidly, provided the wearing agents are not unusually persistent. Rough contact with certain corals can abrade and damage polyps. --

many, many thanks for your reply archman. do you have some sources for this info?

the blind diver i had the pleasure to dive with and guide was extremely careful and knowledgeable. he indeed did not have a sense of his position within the water column, but i would invite you to have an experienced buddy who you can trust completely guide you through a dive while you maintain your eyes closed. i can bet you will get to 'see' things you would otherwise have missed. it might be quite a luxury to be able to shed ordinary associations in such a way.

the blind diver i guided had a very accurate picture of the conditions of the site from touching his way around, carefully and with my guidance, from sponge to soft coral to rock formation or sand chute.

i agree with you that the no-touch policy is a good policy. however, after the experience i had i would be eager to raise my hand to make an exception for blind divers. albeit, they be educated divers. the person i dove with obtained much pleasure from identifying sponges and corals he had studied in depth. not only did he know the ordinary names, in english, italian and sometimes in spanish plus the scientific name but also some of the peculiarities of the feeding and reproduction cycles. ever wonder what fire coral feels like? slightly tap it with a fingernail and the stinging polyps will withdraw. you will then have around 10 seconds to carefully and lightly feel the calcareous surface. again, this type of hands on experiential underwater field trip should not be without restraints and limitations. care and education are key even when exceptions are made for blind divers.

if you have a source or know of any websites i could get more scientific information on i would very much appreciate them. in any case, thanks again for the info you posted.

regards,
mrv.

 

[maractwin]

As someone with a reef aquarium at home, I have some experience handling various reef creatures. Many are quite hardy, though some are very delicate and easily damaged. On a healthy reef, creatures will rebound quickly from minor injuries. But if the reef is under stress, even a minor bruise could kill a coral.

A lot of this comes down to frequency. Touching a hardy coral once a week won't do it much, if any, harm. But if each diver to visit a popular dive site touched a prominant coral, it would be more than that creature could handle. So I think that the occasional exception is OK. But exceptions have to be granted very judiciously, and not very often.

-Mark