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JB63
02/03/2010, 06:40 PM
Lately it became apparent that many Corals can survive low tides and be totally exposed to the scorching sun for hours before the water returns. There are also accounts of salinity increasing in tide pools due to evaporation, though that may be tough to mimic.

The question is, those periods of total sun exposure, is it that Corals tolerate them or, they actually need them to thrive/grow/...

Has anyone tried mimicking tides in their tank? That would involve lowering water level to some extent, then refilling few hours later. That would require a second tank (temp water storage) with a sophisticatred pump/sequencer

Also, what to do about the lights when the Corals are exposed?

ChadTheSpike
02/03/2010, 06:45 PM
Im not sure if you have seen this build or not, but you should take a look... its exactly what you are talking about... I have never tried something like this, but have been following this one closely and very interested...
http://www.manhattanreefs.com/forum/tank-threads/66115-intertidal-reef-flat-mixed-biotope-system.html

JB63
02/03/2010, 07:05 PM
Thanks for the link. I'll check it out.

jbird69
02/03/2010, 07:07 PM
I would think SOME wild corals collected from SOME locations could withstand and even thrive under those conditions. I wouldnt think aquacultured corals would respond as well. I am totally speculating here, but if aquarists are having superb success keeping their corals submerged, what would you be trying to improve by drying your corals in a metal halide sun a couple hours a day?

With that said, the above link is a very intreguing experiment and cool build.

JB63
02/03/2010, 07:12 PM
Some would theorize that when corals are fully exposed, it'll force them to secrete some mucus heavily, thus in the process, ridding themselves of pests and parasites.

ChadTheSpike
02/03/2010, 07:26 PM
I would think SOME wild corals collected from SOME locations could withstand and even thrive under those conditions. I wouldnt think aquacultured corals would respond as well. I am totally speculating here, but if aquarists are having superb success keeping their corals submerged, what would you be trying to improve by drying your corals in a metal halide sun a couple hours a day?

With that said, the above link is a very intreguing experiment and cool build.

my thoughts exactly... its a very interesting build doing something that I havent seen done except with mud and plant setups. I am not sure that it is something that will be successful, but Im looking forward to seeing it! (that builder shares similar concerns about the systems plausibility.

theyammieguy
02/03/2010, 07:34 PM
Thats a very interesting build. I like the way he makes a wave using a deodorant tube.

ChadTheSpike
02/03/2010, 07:43 PM
haha, I have yet to meet a reefer who isnt exceptionally resourceful!!!

theyammieguy
02/03/2010, 07:59 PM
If you used a peice of solid round clear acrylic, you would have a virtually invisible wave maker.

greenbean36191
02/04/2010, 10:32 AM
Lately it became apparent that many Corals can survive low tides and be totally exposed to the scorching sun for hours before the water returns.
Extreme low tides that last for hours are pretty uncommon events. On most reefs where they occur, they happen for 4 or 5 days straight, 2 or 3 times a year but only coincide with scorching mid-day sun every few years. When they do occur at mid-day, they often result in heavy mortality. There was one particularly nasty one about 2 years ago that damaged 50-75% of the corals on one reef on the GBR.

The reefs that see this type of event are pretty easy to spot due to the damage they do too, even at high tide. The reef flat will be very flat with relatively low coral cover made up almost entirely of small colonies of weedy corals like Acropora. Where massive corals do occur they're either very small or have flattened, usually dead tops.

While many corals can tolerate aerial exposure, it's certainly not something that's good for them and it's definitely not something they require, as many reefs never see this type of event.

There are also accounts of salinity increasing in tide pools due to evaporation, though that may be tough to mimic.
Yes, and this is the second most common cause of coral bleaching after high temperature events. It's not something people should try to mimic.

Some would theorize that when corals are fully exposed, it'll force them to secrete some mucus heavily, thus in the process, ridding themselves of pests and parasites.
Producing mucus is about the most energetically demanding thing a coral can do. It's the last thing I would want to force a coral that was already being robbed of resources by parasites to do. Besides, which parasites is the mucus getting rid of? Many of the microbial parasites are not only not deterred by coral mucus, but actually feed off of it. IME, red bugs aren't terribly bothered by mucus either.

Beaun
02/04/2010, 10:51 AM
Extreme low tides that last for hours are pretty uncommon events. On most reefs where they occur, they happen for 4 or 5 days straight, 2 or 3 times a year but only coincide with scorching mid-day sun every few years. When they do occur at mid-day, they often result in heavy mortality. There was one particularly nasty one about 2 years ago that damaged 50-75% of the corals on one reef on the GBR.

While many corals can tolerate aerial exposure, it's certainly not something that's good for them and it's definitely not something they require, as many reefs never see this type of event.


Producing mucus is about the most energetically demanding thing a coral can do. It's the last thing I would want to force a coral that was already being robbed of resources by parasites to do. Besides, which parasites is the mucus getting rid of? Many of the microbial parasites are not only not deterred by coral mucus, but actually feed off of it. IME, red bugs aren't terribly bothered by mucus either.

I agree with GreenBean on these points. The low tides you see on those videos are VERY rare. Not only is it dead low tide on the lowest spring tide (twice a month), but it is dead low on the lowest spring tide at the height of the sun. In the end, this only lines up to happen a few times a year.

Simon Garratt spoke at one of our LIRA reef meetings about this tide system he is doing. It is very interesting, but I question what it will achieve in a reef tank. What benefits are gained by raising and lowering the water, other than looking cool?

jbird69
02/04/2010, 11:03 AM
It would be interesting if someone had the resources to build a true tidal zone reef. One where small waves constantly break and wash a reef crest with foam and turbulence. Allwoing corals to protrude occasionally but with the benefit of a consistent washing. Would be interesting to see the health develope in such a system.