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Scuba Forum / General / October 2003What is your Deepest Coral Found?
Hello, I was doing some research on coral in the Red Sea. I was wondering, has anyone found coral down to 200ft? Anyone know of any good resources that have been written on the subject? And what have you personally seen? Thanks for all of your help. JM > Hello, > > I was doing some research on coral in the Red Sea. I was wondering, > has anyone found coral down to 200ft? Anyone know of any good Yes. > resources that have been written on the subject? And what have you > personally seen? > > Thanks for all of your help. > > JM > I was doing some research on coral in the Red Sea. I was wondering, > has anyone found coral down to 200ft? Anyone know of any good > resources that have been written on the subject? And what have you > personally seen? The Darwin Mounds off the coast of Scotland are coral reefs in about 1000m of water. A google search for them should turn up some details. Jason  SignatureSee http://www.scuba-addict.co.uk/ for UK diving reports including trips to Plymouth, Weymouth, Falmouth, Exmouth and Scapa Flow > Hello, > [quoted text clipped - 6 lines] > > JM The depth limit of coral is the depth at which light ceases to penetrate all the time. That, of course, varies radically from locality to locality. The polyp can (and does, for a while) survive without photosynthesis, and it can cheat by absorbing zooanthellae that have rotated from shallower or clearer water, but generally it needs photosynthetic zooanthellae to live, therefore some light penetration. Since there are waters in some places thousands of feet deep with light penetration, there is no reason why corals should not be happy there. > > I was doing some research on coral in the Red Sea. I was wondering, > > has anyone found coral down to 200ft? Anyone know of any good [quoted text clipped - 13 lines] > Since there are waters in some places thousands of feet deep with light > penetration, there is no reason why corals should not be happy there. Light levels at 'thousands of feet deep' is not enough to support photosynthesis. 'Reef-building' coral, I think, has been found down to 150m in very clear water. I guess there would not be much of it, nor would it be growing. 'Deep water' coral can exist at 2000m depth and get all their food by filtering particles in the water. http://www.soc.soton.ac.uk/GDD/DEEPSEAS/coralecosystems.html S.C. >> > I was doing some research on coral in the Red Sea. I was wondering, >> > has anyone found coral down to 200ft? Anyone know of any good [quoted text clipped - 21 lines] > 'Deep water' coral can exist at 2000m depth and get all their food by > filtering particles in the water. There are places where the waters are clear enough to support photosynthesis to thousands of feet. 150m is pretty shallow and there is plenty of light in many places. Hard corals are abundant at 80m in the Bahamas (as deep as I've been there) and I'd be willing to bet there are plenty at 150m on the same walls. But you are right that as depth increases (ie light penetration decreases) corals depend less on photosynthesis. They also change shape, increasing their surface area to mass as they go deeper, and the way they rely on zooanthellae to provide the nutrients created by photosynthesis. The planula larvae of many shallow water corals leave the parent with their own culture of zooanthellae, and have relatively high metabolic rates. In deeper waters, the corals have lower metabolic rates and depend more on "captured" products of photosynthesis brought there by convection. (And, of course, all generalizations are false.) Zooanthellae-dependent corals rely on the zooanthellae to process waste ammonia and CO2. I don't know how deep water corals do this. Perhaps just pee in their polyps. Also, corals not only filter feed, but also absorb certain nutrients directly from the water via microvilli. > > Light levels at 'thousands of feet deep' is not enough to support > > photosynthesis. 'Reef-building' coral, I think, has been found down to 150m [quoted text clipped - 3 lines] > There are places where the waters are clear enough to support > photosynthesis to thousands of feet. Hey Mike, Genuinely curious, can you give any references to support that? I've searched but haven't had any luck finding any proof of your statement. Leafing through a textbook, it states that the photic zone has a max depth of about 100m - 150m. I've read other sources that say down to 200m, not read anything claiming deeper, let alone to that magnitude. Photic zone (where photosynthesis is possible), is usually defined as where light is 1%, or sometimes 0.1% of surface intensity, (thus probably the variation in 100m - 200m). Thanks, S.C. > Genuinely curious, can you give any references to support that? I've > searched but haven't had any luck finding any proof of your statement. [quoted text clipped - 5 lines] > or sometimes 0.1% of surface intensity, (thus probably the variation in > 100m - 200m). Thousands of feet I can't defend. I get carried away sometimes. But I have been deep on the walls off Cat Cay, near Bimini, when I could see the barnacles on the boat 200' above and very clearly see small stuff further than that below. That's a round trip of 600'+ for lots of light. It might be interesting to scrape algae samples off the walls there... I'd bet money the photic zone is well beyond 200m. Good doctoral thesis project. I'd be surprised if anyone has actually done the research to prove (or disprove) "the deepest", though 200m is prolly beyond the limit in most places. I also dove Lake Travis, where the photic zone ends at 2 inches. On a good day. The book writers may be doing some averaging... > > Genuinely curious, can you give any references to support that? I've > > searched but haven't had any luck finding any proof of your statement. [quoted text clipped - 18 lines] > disprove) "the deepest", though 200m is prolly beyond the limit in most > places. deepsea coral http://www.ices.dk/marineworld/deepseacoral.asp I also dove Lake Travis, where the photic zone ends at 2 inches. > On a good day. The book writers may be doing some averaging... >> I'd be surprised if anyone has actually done the research to prove (or >> disprove) "the deepest", though 200m is prolly beyond the limit in most >> places. > > deepsea coral > http://www.ices.dk/marineworld/deepseacoral.asp We're talking photosynthetic coral, hosting zooxanthellae. Lophelia sp. doesn't count. >> The depth limit of coral is the depth at which light ceases to >> penetrate all the time. That, of course, varies radically from locality > photosynthesis. 'Reef-building' coral, I think, has been found down to 150m > in very clear water. I guess there would not be much of it, nor would it be > growing. Probaly the biggest coral reef in the world is in Norway and is at depths between 200 and 400m. No that types of coral isn't using fotosyntesis at all. This coral bouild reef and isn't depending on sunlight. However the reefs arn't that colurful as there is no fotosyntesis in the corals. / Balp Signaturehttp://anders.arnholm.nu/ Keep on Balping Doing a google search for "deepsea coral" reveals that reefs have been found as deep as 3000 meters. Apparently there are lots of reefs in the north atlantic which start below 200 meters and are common up to 1000 meters in depth. later Steve > Hello, > [quoted text clipped - 6 lines] > > JM |
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