Soft-water Daphnia...

[froggy]

Hi all

I live in an area with extremely soft water and have always had to go through the lengthy process of producing harder water for Daphnia cultures - consequently, I rarely bother.

However, I recently discovered in a Mantella tadpole aquarium a swarm of a small species of Daphnia, which I am now culturing very successfully. The water they seem to thrive in is tanin rich, with a pH of about 4.5 and basically no hardness (you can leave a jug to evaporate without any limescale).

Has anyone else found strains of Daphnia that do well in soft water? I don't understand how they can make their shells...

C

 

[Coastal Groovin]

I have found Daphnia in general do better in soft water. They are normally found in tempory pools that fill with rain water. Which of course is as soft as nature gets.

 

[caleb]

It's never occurred to me before, but all of the best Daphnia colonies I know are in concrete ponds, so presumably pretty high in calcium.

I guess they can pull sufficient calcium from even very soft water- they are pretty good at accumulating nutrients from the water, and there should be a little bit of calcium in there... you can find out from your water
company just how much there is in your tap water- is this your area?
Water quality testing and standards | About your water | Your water supply | Business customers | United Utilities

My tap water is supposedly 54mg/L calcium ("slightly hard"), and Daphnia do OK in this.

 

[froggy]

I'd already checked that site, Caleb '- my water is 8.77 mg Ca per l! Incredibly soft and Daphnia have never done well in it before, let alone in tannin rich acidic water. This species/form is very small, so perhaps that's how they cope with low calcium levls - they just make less of themselves!

Anyway, I'm not complaining - I'm happy to finally have a culture!

 

[Fishfur]

It would be very interesting to know what species of daphnia they are. Any chance of getting a microscopic look at them and a pic from the scope ? Maybe a student could do that in school, since I bet most of us don't have a scope at home ?