Daphnia culture faulure
Posted 24 July 2014 - 02:06 PM
I let rain water over flow the vat for water changes and i feed them a yeast sugar mixture five gallons at a time but the last week as seen the yeast vanish over night but daphnia yields are very low, not enough even for one breeder tank of black bands. The sides of the vat are covered by what looks like a detritus layer but that is algae and dirt and is always present.
I can't see any hydra which isn't really surprising as bad as my eye sight is these days but I am pretty careful not to introduce materials that might have hydra but that doesn't mean they have't found a food hold.
Any thoughts, suggestions?
Posted 24 July 2014 - 03:06 PM
Posted 24 July 2014 - 03:07 PM
Posted 24 July 2014 - 08:55 PM
Like Gerald said. The key is keeping multiple containers with greenwater, so that you have plenty of daphnia food, and your culture is spread out. Rotate them. You will still have crashes, but will still have plenty to keep it all going. When I was culturing daphnia, I was using kiddie pools. I had 7 and rotated them regularly. I also used a bit of miracle grow here and there to maintain fertility. I was able to harvest well over a quarter cup a day. May have been more.
I dont why they crashed, but every Daphnia culture does crash eventually. Maybe it's due to successional changes in the mix of phytoplankton, with a shift toward species that are bad-tasting, non-nutritious, or toxic to Daphnia. Keeping multiple containers going and restarting periodically when production falls off may be a better strategy than relying on one big permanent culture.
Posted 25 July 2014 - 07:53 AM
Posted 25 July 2014 - 11:25 AM
The first thing that comes to mind for me is a calcium deficiency if the water is primarily replenished by rain. Daphnia are crustaceans so, like crabs, their shell is made of calcium carbonate. They need at least some mineral hardness to grow and reproduce.
That is a good thought. It is hard to say though if calcium is the problem, or if this is just a regular daphnia crash. This kind of goes hand in hand with what David said.
Add some calcium.
Posted 25 July 2014 - 09:48 PM
Posted 26 July 2014 - 11:26 AM
Posted 26 July 2014 - 07:01 PM
Posted 26 July 2014 - 07:24 PM
Surprise to me but it looks like they may not only compete for food, but even prey on your daphnia. I have a hard time imagining a tadpole being able to chase down anything, but I guess I am wrong.
I'll have to dip them out, they might be bullfrog tadpoles, one was in my vat the other day, not sure how a toad could jump 30 inches...
Posted 26 July 2014 - 07:45 PM
Posted 28 July 2014 - 12:07 PM
Posted 28 July 2014 - 08:13 PM
I dont think tadpoles have much effect on Daphnia. They eat mainly attached algae, while Daphnia eat free-floating planktonic algae. They might even be beneficial for that reason. You can distinguish Hyla (treefrogs) from Rana (true frogs) tadpoles by the dorsal fin attachment -- it extends farther up the back on treefrogs. Also our NC treefrogs will metamorphose when the head-body is less than 1" long. Green frog and bullfrog (Rana) tadpoles are mostly bigger than 1" when the legs appear.
I caught them all and put them in a small wading pool I had set up, I'm feeding them fish food, we can always use more frogs!
My daphnia culture is back to normal, I harvest about a half cup once a day it doesn't seem to have any effect on their numbers.
Posted 28 July 2014 - 08:47 PM
I say leave the tadpoles in with the daphnia, it will help lessen the chance of bd infection in the frogs (I'm not totally serious about doing so but there has been some research on it http://www.the-scien...Killing-Fungus/).
Too late, already moved them, I am pretty sure they are toad tadpoles, I figured out how they could get in my daphnia vat. I still have a big bull frog visiting the vat, I love to listen to them at night, I grew up listening to bullfrogs call in the night, I could hear them from over a mile away...
Posted 30 December 2014 - 05:25 PM
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