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Light and bs-hatch rate. (was Re: Live Foods Digest V1 #85)

Alfred A. Skrocki wrote:
> Mr. Huntly I have been raising brine shrimp for over 30 years in a DARK
> room as almost all aquarium suppliers do, for they know as I do that brine
> shrimp need very little light, they need mostly heat! 

This isn't very important, and we honestly don't need to argue about
"angels dancing on the head of a pin." I do feel I should correct a
couple of your misconceptions, FWIW to the list. Developing bbs *do*
need very little light. That's not what I was talking about, at all.
Please read what I said.

I have been "hatching" brine shrimp for *considerably* more than 30
years, so I have learned a couple of things. One of those is that
"raising" them is mostly an exercise in futility. Their food value is
astonishingly low unless raised in a live-spirulina-rich environment.
That's just too hard for me to do at home. Also, I'm lucky enough to
live right by where they are collected by SF bay, so I get very
nutritious adult Artemia, either from the salt ponds, or my LFS for a
buck an ounce.

> Yes brine shrimp
> will react to light by moving to it, but this is only to get the heat it
> normaly provides. This I have proven by setting up several tanks with both
> bright light sources and dim lght sources with the same amount of heat as
> the bright light tanks and there was NO DIFFERENCE in the development of
> the cultures! 

I was talking about the photosensitivity of the *hatch rate*. If you are
satisfied with 60-80% on eggs capable of 90%+, we have nothing to
discuss. As prices are rising, again, (and I use a *lot*) it really
matters to me.

>I asume your post was well meaning and as such I would
> suggest you go and read the literature and join the Brine-L list before
> making such remarks.

Thanks for your assumption. I make my living in the optics business, so
have considerable curiosity about photoactive events. I've read a *lot*
of professional literature on the subject, as a matter of fact, and even
written some of it. I might even be able to dig out some references on
the need for spirulina, for Artemia to be worthwhile food.

How bright is "bright?" It takes a *lot* to see any effect.

IDK the exact light level to optimize hatch rate, which is why I
referenced Dr. Kawahigashi, of SF Bay Brand. Let me give you a rough
guide, tho. A well-illuminated desk or bench top is usually getting
about 100-200 ft-Candles*. His suggested 2000 is more than ten times
that strong, and probably approaches daylight (if you are far enough

I really don't think we disagree. You just may have missed my point that
I was talking about the well-known *hatch* photosensitivity. If it was
my poor choice of words, please forgive me. Sometimes I dash things off
to the lists a bit too quickly.


* Please forgive the original units goof. I didn't really mean
ft-Lamberts. ;-)

Wright Huntley, Fremont CA, USA, 510 494-8679 huntley at ix_netcom.com
"Subvert the dominant paradigm!"