sedimentation and coral stress
cbingman at netcom.com
Wed Jun 18 13:47:22 EDT 1997
On Wed, 18 Jun 1997, Rebecca Penwell wrote:
> I am trying to keep Acropora cervicornis in lab conditions but I
> am not having much luck. Each coral is in a 10l tank no filter,
>airstone for circulation,
This is probably inadquate water circulation. For a 10 liter tank, I
would suggest adding at least a MaxiJet 250 powerhead to each tank.
>light metal halide 450 watts,
Without knowing more about the geometry and type of lamp, you could have
more light than the corals need, too much UV, etc.
The water is too hot. Things happen too quickly at 90 F, and that water
temperature is almost high enough to cause bleaching at ideal
conditions. I would suggest lowering the water temperature to 27C.
> fed brine shrimp every 3 days,
Adult brine shrimp are too large for A. cervicornis polyps to capture.
Artemia nauplii would be a more acceptable food, but strictly, the corals
don't need food over thie timescale.
I suspect that the feeding may be contributing to poor water quality as well.
Ideally you would feed brine shrimp nauplii and then do a 100 percent
water change several hours later.
You should also monitor the total alkalinity and pH in the test aquaria.
If the corals are calcifying rapidly, they can reduce the total
alkalinity in this volume of water substantially over the course of a
single day. I don't know how large the corals are, but in my experience
fields of small coral cuttings can calcify at or above 20 kg m-2 yr-1.
You may need to increase the total alkalinity with something like sodium
bicarbonate or a mixture of sodium bicarbonate and sodium carbonate.
If you want to maintain calcium as well, I would suggest making a stock
solution of 0.5 molar calcium chloride and another stock solution of
(0.8 molar sodium bicarbonate + 0.1 molar sodium carbonate.) These
solutions will be balanced in calcium and alkalinity when equal parts of
both are added to the test tanks.
You may also wish to increase the frequency of water changes to every 2
days or every day.
> water change with real seawater every 4 days and they
> do not live more than a week and I am interested in keeping them for at
> least 3 weeks. Any help would be greatly appreciated, salinity 35 ppt,
> and ph 8.2 THanks!
If after you make these changes, you still have a problem with coral
mortality, please e-mail me and I will send you an antibiotic treatment
protocol which will dramatically lower the chances of the coral dying of
a bacterial disease during the course of your study. However, it is
probably best if you can avoid this.
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