NANFA-- outdoor daphnia magna - they appear to be back
Fri, 10 Dec 1999 16:22:40 EST


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."

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