[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Live Foods Digest V2 #212
- To: Live-Foods at actwin_com
- Subject: Re: Live Foods Digest V2 #212
- From: John Clare <clarej at tcd_ie>
- Date: Sat, 3 Oct 1998 00:48:22 +0100 (BST)
- In-Reply-To: <199810021958.PAA15348 at acme_actwin.com>
The presence of large amounts of ammonia retards growth in a lot of
organisms and daphnia are no exception, but the slow/little movement tends
to suggest the presence of nasty ions in the water, usually metals from
pipework or the treatment works. There are really a lot of possibilities
here, and it could be as simple as a build up of waste metabolites in the
water (usually the water gets a brown tint to it after a while when they
get into high concentrations). I did an experiment recently (sadistic
bugger that I am) and didn't change the water in a 20 litre magna tank for
3 weeks. Only water I changed was a litre of water for every litre of
green I put in. Fed every day, the population exploded after a few days,
reached a peak at about 17 days, and then dropped like a hot potatoe to
slightly more than 0 live daphnia at the end of 3 weeks, simply from
metabolite build up in the water.
Good thing to remember is that water testing companies/institutions often
use young D. magna (less than 24 hours old) to test water for metal ions
and certain other toxic substances. The tests are measured in
two ways - a percentage of the Daphnia lose mobility and/or
heartbeats will be measured (you'd be surprised how many times a
minute a Daphnia's heart beats).
> Date: Fri, 02 Oct 1998 09:29:18 GMT
> From: spflume at gwdg_de (Stephan Pflume)
> Subject: Re: Live Foods Digest V2 #211
> On Thu, 1 Oct 1998 15:58:01 -0400 (EDT), Owner-Live-Foods at actwin_com
> (Live Foods Digest) wrote:
> >Your green water pH problem probably stems from the starting pH of the
> >water, the dissolved salt content and the ammonia levels (I guess you know
> >that though). As long as you keep the ammonia levels down, D. magna and D.
> >pulex can do well at anything up to 9 from what I can tell. If only
> >ammonia didn't change in toxicity with pH :(.
> Hm. I haven't measured anything. I just tried to rear Daphnia magna in
> an outdoor tank, which had become green during some weeks before. Well
> though these stayed alive, they became rather lucid and reproduced
> rather slow.
> - --
> Stephan Pflume
> Abt. Vegetationskunde und Populationsbiologie
> Wihlelm-Weber-Str 2. 37075 Goettingen
> End of Live Foods Digest V2 #212
> To unsubscribe from live-foods, send the command:
> unsubscribe live-foods
> in the body of a message to "Majordomo at ActWin_com". Archives are
> available on the web at http://www.actwin.com/fish/live-foods
> or via FTP to ftp.actwin.com in /pub/aquaria/live-foods.
"Language has not the power to speak what love indites:
The soul lies buried in the ink that writes."
eirinn at valhalla_com (http://www.maths.tcd.ie/~jpc)