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NFC: RE: outdoor daphnia magna - they appear to be back
Chuck
As can be seen in the text below the Daphnia ephippia (resting eggs) do not
have to be either dried out or froze in order to hatch; although they can
with stand either on or both and still be viable.
Gay
=============================
Hatching Daphnia ephippia (resting eggs):
I have started Daphnia from ephippa (resting eggs). Easy? If you've
hatched fish eggs, I'd say yes. If you are getting ephippa (resting eggs),
they will appear in black saddles on the females. Take enough water from
the tank to fill a 10 gallon tank with about half an inch of water. Catch
out the saddled females and put them in this half inch of water. Allow the
tank to completely evaporate. Wait a few weeks, and then fill the tank all
the way up. > An amazingly tough egg. It can withstand being dried out >
and sun baked, frozen.
Question is how long can they remain dormant and the eggs still be viable ?
I've read somewhere they can remain viable for years.
Ephippia are the resting eggs that can withstand freezing and drying
conditions. They are black, saddle-bag shaped, and pretty hydrophobic,
about 1 to 2 mm long and look like specks of pepper, some of which will
float on the surface of the water and others which will sink to the bottom
of the culture container. What is nice is that they will also withstand
sterilizing in a three to five minute bath in 5% Clorox solution, which very
few microorganisms will do. Just rinse them after this and put them in some
aquarium water and place in the refrigerator for about two weeks. Fill a
two to ten gallon aquarium with
All Daphnia species produce large black ephippia (resting eggs) if exposed
to too high or too low a temperature, lack of food, over crowding or too
short a light period. In these cases some of the Daphnia will become males
and mate with the females, producing ephippia (resting eggs), which can
resist drying and freezing. The ephippia (resting eggs) look like specks of
pepper, some of which will float on the surface of the water and others
which will sink to the bottom of the culture container. Once this starts to
happen the culture is probably going to die out soon unless conditions
improve. If you ever have a "crashed" Daphnia culture, DON'T THROW IT OUT!
The hatching of resting eggs ( ephippia) is triggered by an abundance of
food, good water conditions and a lack of adult Daphnia.
1. Place the Daphnia ephippia or the "mulm" from the bottom of the
crashed Daphnia culture in a container of water in the refrigerator for
about two weeks. Fill a two to ten gallon aquarium with hard alkaline water
the same temperature as the temperature in the refrigerator. Aerate lightly
and add the ephippa (resting eggs). Allow the water to reach room
temperature naturally and slowly. Once the Daphnia have hatched, aeration
is optional. Tank should be lit with a timed light at least twelve hours a
day, or you can leave the light on 24 hours a day.
2. Another hatching method is to place the ephippia resting on the
bottom in the mulm and a little fine peat moss in a ten gallon tank with
less than a half inch of water. Allow the water to slowly evaporate. After
the tank has been dry for at least a week, completely fill the tank and
lightly aerate. Usually only a few eggs hatch at an attempt. This is
nature's insurance policy that the Daphnia are not wiped out by fickle
weather. Each time you repeat these processes, a few more eggs will hatch.
3. Or another method is consists of nothing more than doing nothing
assuming the crashed culture doesn't smell bad. Just leave a light on over
the crashed indoor culture for 24 hours a day, keep it at around 72 degrees
Fahrenheit (22 degrees Celsius) in the presence of good Daphnia water
parameters water. The water will green up and often Daphnia will then
appear as most of the embryos in the ephippia resting in the mulm on the
bottom will hatch within a 10 days to 2 weeks.
The above methods will work for any and all Daphnia cultures be they Daphnia
magna, Daphnia pulex or Moina. If they don't appear or you are in a hurry,
then seed the tank from another culture.
=======================
-----Original Message-----
From: CEFCHURCH at aol_com [SMTP:CEFCHURCH at aol_com]
Sent: Friday, December 10, 1999 12:39 PM
To: nfc at actwin_com
Subject: NFC: outdoor daphnia magna - they appear to be back
History:
Last spring, I threw some daphnia magna in a 300 gallon plastic
rainwater
pond and was amazed at how prolific and large they became. During
the heat
of August, the culture disappeared. Water temperature at the bottom
of the
pond climbed to the low 90*'s F.
Since then, I cleaned the pond out but kept a few 5-gallon buckets
of water
and pond mulm outside just in case they came back (and to grow
mosquito and
bloodworm larvae in). I was told that the culture would/might come
back from
(I assume) dormant eggs once things cooled off. There were none in
there a
week ago but today much to my surprise, four of the buckets seem to
have
significant numbers of what appears to be very small daphnia
swimming around.
It has been a warm and dry Fall as things normally go here in the
Midwest.
In the last couple weeks, the temperatures have dropped to the 20's
and have
gotten up to the 60's during the day. Last week, we had a couple
inches of
rain which of course may have stirred things up in the buckets.
Comments about the cycle appreciated. Do the eggs need to go
through a
freeze/thaw cycle before they start hatching again? Do you think
the couple
inches of fresh rain had anything to do with it?
My next step will be to net all the feeder goldfish out of another
300 gallon
pond (where the water changed to a wonderful green color) and put
some in
there. And also bring some indoors.
Chuck Church
Indianapolis, Indiana USA
"Nobody likes Green Water except people who raise live fish food."