Daphnia disappeared

[bumblebee1]

All my Daphnia have disappeared from my pond in last two weeks although other pond life still alive (newts,snails,water slaters).Any ideas what may have caused this,I have not topped up the pond but it has been full due to large amount of rainfall.Any help appreciated thanks.

[Ukwildlifeo]

heh - Ive just been reading about this for my project.
Basically Daphnia are filter feeders, and therefore really on algae in the water, or phytoplankton, to feed. The algae tends to bloom in spring or early summer when it warms up, and the daphnia reproduce in large numbers. But the algae end up using all the nutrients up, and this combined with the massive amount of grazing by the daphnia, means the amount of algae plumets. Then the daphnia stop reproducing as much and/or die of starvation. Meanwhile many of those that are surviving are being eaten by the pond predators - the end result of all this is much less daphnia - until next year

[djackso]

In my pond, leeches attach themselves to the underside of leaves such a lilly pads and basically "hoover" up the daphnia. I'm sure this is where a lot of those in my pond have gone.

[Dogghound]

Also heavy rainfall/cloudy cool weather reduces algae reproduction so these spells can cause temporary shortages but populations fluctuate.

[bumblebee1]

Thanks I have noticed a couple of leeches in the pond and algae has been increasing so I will leave nature to run it's course and hope they return.Hopefully a bit more sunshine will help the problem!!!