Mesophotic Corals ("Twilight zone")

Discussion in 'General Discussions and Advice' started by Jaco Schoeman, 28 Jan 2010.

  1. Jaco Schoeman

    Jaco Schoeman MASA Contributor

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    Credit to FransSny on this. He sent me this link...

    Okey so we all know about Photosynthetic Corals (Light dependant) and Non-Photosynthetic Corals (Light Independant.) But has anybody ever heard about Mesophotic Coral Ecosystems (MCE's)?????

    MCE's are defined as light-dependent coral communities (and associated communities of algal, sponge and fish species) that occur in the deepest half of the photic zone (starting at 30-40 m and extending to over 150 m) in tropical and subtropical regions.

    Also called the "twilight zone"

    The main definition of MCE's, is that it corresponds to the maximum depth at which there is enough light to sustain photosynthesis in zooxanthellate corals.

    Many of the the shallow water coral, fish and invert species are found in MCE's. The wonderful advantage of this, is that at these depths, recreational divers can not reach the life forms, thus it is a refuge for many species, that will never be harmed by man for harvesting etc.

    When I went through this, I could not help but as the same question I have asked so many times: "are we not missing the target when we light up our softies in the hobby?..."

    Below are some interesting images, and once you have gone through them, you might relook your 250W MH over those mushrooms...


    Here is sub used for sampling and photography, at these depths

    [​IMG]

    Tube anemone at 112m!!!!

    [​IMG]

    Plating Monti at 61m deep (where's the MH's????)

    [​IMG]

    Sub taking samples:

    [​IMG]

    [​IMG]

    Look at this!!! Zoa's, mushrooms and even LPS at 63 meters deep!!!

    [​IMG]

    Proof of this depth:


    [​IMG]

    Muricea sp. at 55m

    [​IMG]

    Swiftia sp. at 57meters

    [​IMG]

    Roughtoungue Bass at 86m

    [​IMG]


    Squirrelfish at 95m

    [​IMG]

    Then here is an article extract of new species of damsel that was found

    [​IMG]

    "The International Institute for Species Exploration at Arizona State University announced the top 10 new species list for 2008 which includes the discovery of a mesophotic damselfish, Chromis abyssus, by Rich Pyle. The list draws attention to the undiscovered biodiversity on this planet. Discovered off the Belau Islands (Palau) at 110 m, this “damsel in the deep blue sea” is dark gray with a large iridescent blue spot at the center of each scale. Direct observations and hand collections were accomplished while diving on mixed-gas closed-circuit rebreathers. Results indicate that C. abyssus prefers depths in excess of 115m and lives among boulders and rock outcroppings."

    Amazing what we still have to learn about the ocean, and trying to keep it in our livingrooms huh?
     
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  3. dallasg

    dallasg Moderator MASA Contributor

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    yes, i did a paper on the "Twilight Zone", also known as the cryptic zone.
    i have setup a cryptic zone filter as part of this research, i got alot of information from Steve Tyree and Simon Garret, if u would like more i can look for the paper and post it.
    called Welcome to the Twilight Zone
     
  4. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Yeah, why not. Might be interesting ;)
     
  5. dallasg

    dallasg Moderator MASA Contributor

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  6. jacquesb

    jacquesb Retired Moderator

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    WOW Jaco / Frans. VERY VERY interesting indeed.

    Dallas ReefEden is Simon Garrett's personal website....
     
  7. dallasg

    dallasg Moderator MASA Contributor

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    yip i know, i got tons of info from him...
    really interesting site
     
  8. poiromaniax

    poiromaniax MASA Contributor

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    Thanks for this guys.

    But with our corals, surely the depth at which they are collected plays a massive part.

    those corals must have had YEARS to adapt to the "twilight zone"?
     
  9. dallasg

    dallasg Moderator MASA Contributor

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    funny, while diving in dec in mozambique, i noticed that even on the deep reefs, starting at 40m i found more life and coral variations then on the 12-18m reefs.
     
  10. Boegie

    Boegie

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    Great thread, thanks.
     
  11. poiromaniax

    poiromaniax MASA Contributor

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    I just thought of a possible reason - 99% that im completely wrong :p


    When the corals spawn, their eggs and sperm must drift more towards the bottom, a la Marine Snow.

    That would explain why there is much more variety at greater depths?
     
  12. dallasg

    dallasg Moderator MASA Contributor

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    thats a good idea, makes 100% sense...
     
  13. Jaco Schoeman

    Jaco Schoeman Thread Starter MASA Contributor

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    Not only that Poiro, I think a lot of coral species get "damaged" in shallower waters due to the turbulance there... Whereas at great depths, you have a more steady, however strong flow, but not as violent. The interesting thing to me however, is the lack of light they live under. That is what I think we should think about carefully.
     
  14. dallasg

    dallasg Moderator MASA Contributor

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    i wouldnt say lack of light, at 40m there is still a fair amount
     
  15. poiromaniax

    poiromaniax MASA Contributor

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    I would love to see some results with a PAR meter at those depths, would be interesting to know what they are!

    What do you guys think of my previous post WRT light - #7?
     
  16. poiromaniax

    poiromaniax MASA Contributor

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    anyway, if there was hardly any light, surely you would see some of the less nps corals there (stereonephtya for one)
     
  17. jacquesb

    jacquesb Retired Moderator

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    Poiromaniax - these coral patches sometimes "just appear" - I would rather think that it has to do with the fact that their eggs/sperm gets deposited at these depths.

    My personal opinion is as follows: all corals have the ability to adapt to a very wide range of lighting/nutrient level/water temps..... BUT, this must be over a period of time (it does not mean it has to happen over millenia - it can be over a period of a few weeks)...... So - to me, it is not strange that the corals are here - it's just that it's awesome to hear of and see proof myself! (I too dived those reefs that Dallas is talking about - and I know what he is talking about - been there - done that - got the reef T-shirt at Ponto!) ;)
     
  18. jacquesb

    jacquesb Retired Moderator

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    W.r.t to NPS corals - they will go where there is more than plenty of food in the water. So - wherever they can feed most. Not specifically in "dark areas"..... ;)
     
  19. dallasg

    dallasg Moderator MASA Contributor

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    yup i agree, NPS coral just dont use light for food, but that doesnt restrict them to dark areas, in moz, i think its kev ledge, there is a huge sea fan at 12m
    let me see if i have a pic of it
     
  20. jacquesb

    jacquesb Retired Moderator

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    Jip - and at Protea Banks (nothern pinnacles) there is a amphitheater type cavern where there's probably about 40 square metres of sun-corals..... (this is at 36/38 metres).

    And at one of the dive sites (cannot remember 100% which) at Aliwal Shoal, there are black/green sun-corals at between 18 and 25 metres..... (I think that it was at Guitar Shark Alley - not 100% sure)....
     
  21. dallasg

    dallasg Moderator MASA Contributor

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    here are the pics, sorry no flash used

    here is the fan at 12m or so
    [​IMG]

    here are some nice hard corals, note the clam etc at 43m at atlantis reef
    [​IMG]
     
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