Re: [Killietalk] daphnia eggs

["J. C." <hillbillynursery at yahoo_com>]

 Well I found something more what I was looking for
last night. It has been studied. When you grow daphnia
indoors in bare bottom containers the eggs are easy to
collect when you do get them stimulated to produce
them. I wish I would have saved the pdf location to
share it. It did say each specie and even each
collection was different. Other than controlled
cooling there was no sure fire way of getting the
daphnia to produce the resting eggs. The rest of the
triggers were very unpredictable. The method use to
store the eggs determines the length of time needed.
If you dry the eggs you have to store them 3 weeks or
more and like our Notho. eggs they will not all hatch
on the first wetting and auctually very
few(percentage) will hatch each time upto 10 wettings.
With cold water storage the eggs need only 2 weeks of
40F tempature and then a warm cold cycle back to warm
and they will nearly all hatch. It does mention
freezing the eggs for 2 months then giving a slow warm
up but you get fewer to hatch out. The times given are
averages and are not rules like our resting fish eggs.
It was just one of those things burried in sceintific
lit.. So maybe this will help others as well.

 My reasoning for wanting to know is I plan on keeping
my cultures going year round. Incase of problems I
want to be able to restart a culture on demand from
resting eggs. I still have nothing like how long they
can go before hatching them. But having the shortest
time frame will help.

                       Later, John

--- Barry Cooper <bjc3 at centurytel_net> wrote:

> John,
> 
> the point is that there are no standardized ways to
> collect ephippia, 
> which is apparent from the manual. It does give
> general guidance for 
> stimulating their production, such as crowding the
> culture. The ephippia 
> would be in the sediment, but isolating them seems
> to me to be well 
> beyond the capabilities of the average hobbyist.
> Probably the best that 
> can be done is to store the sediment. Again, the
> manual states that no 
> standard hatching conditions have been established.
> In other words, the 
> whole thing is a very inexact science.
> 
> I am not sure why you want to do this. My own
> experience is that daphnia 
> cultures come back each year. When I lived in
> upstate NY I had a 300 gal 
> water trough containing a daphnia culture. That
> would bloom during the 
> spring-summer-fall and freeze solid in the winter.
> Each spring the 
> daphnia returned, not doubt from ephippia in the
> sediment. The winter 
> freeze and spring thaw were part of the conditions
> that allowed them to 
> hatch.
> 
> If the experts who wrote that manual don't know
> exact procedures for 
> producing and hatching ephippia, I think you can
> assume that the 
> knowledge doesn't exist. The best you can do is
> follow general 
> guidelines as offered in the manual and by people
> like Joe Bulterman.
> 
> Barry
> 
> Barry J. Cooper
> Sweet Home, OR 97386
> 
>

John Cox of Cumberland Killifish
 Honey Robber beekeeping and removal services
 
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