[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re:Daphnia generations

> From: "Daniel McMonigle" <Mcdaphnia at msn_com>

>  Bill, I have kept a dozen different varieties of Daphnia over the years,
and I noticed plasticity, adaptation, change within weeks of starting up the
majority of them. It could be that in those, that although the daughters
would be clones of their mothers, there could be a large pool of original
mothers, giving lots of genetic variety at the start. Also I have been able
to find a male or two almost any time of the year if I look carefully. I
suspect that some sexual reproduction may be going on simultaneously with
the asexual in those varieties that adapt or change quickly.
I would also observe some eggs being carried by my daphnia throughout the
summer in weather like we are having now - high 93 degrees F, low 70 degrees
F. The cultures have often in the past and may now continue all summer
without crashing (I hope). I guess that is nature's way of hedging her bets.

Sometimes a culture will completely crash in the hot weather. Usually they
will start up again in the cooler fall. There's at least two generations by
sexual reproduction per year.

Dan also observed the differences in color and suggested that often it is a
reflection of environment and or diet. He then observed that his indoor
strain(s) especially tend towards red most of the time.

Blood worms are very red. Am I correct in assuming that this is a result of
the hemoglobin generated in them?

In really warm weather, our daphnia gets pretty orange/red. Would this also
be an increase of hemoglobin produced by the daphnia as a response to the
oxygen depleted water?

(Here's the fun speculation) Would it be that, according what survives to
reproduce, that Dan's Russian strain of Daphnia, benefiting from the
hemoglobin content in the blood, is indeed changing/ adapting to indoor, ie
warmer, conditions?

My indoor culture crashed. I was thinking of just tearing down the tank. Now
I'm thinking of just doing a water change above the mulm layer (with any
resting eggs) and then refilling the tank with greenwater, leaving a light
on over it 24/7 and keeping that strain in the fishroom. Although I have had
a hobbyist's strain of daphnia for a little over 20 years, usually indoor
stuff has been reseeded from the outdoor cultures.

What do you think?

Thanks and all the best!