# Temperature range for daphnia outdoors?



## Mike~~ (8 Apr 2019)

I've just started growing daphnia at home. I've got two populations in glass containers: one indoor set-up with a bubbler and artificial light; and the other set-up outdoors in the sun and the wind.

My question is what temperature range is survivable? I'm in New Zealand and it does get cold here in the winter. I'd expect down to maybe -3°C on the coldest nights. It won't freeze the container solid, but it would chill the water to zero - I guess there is some risk of skinning over with ice and losing oxygen exchange.

Would you expect the outdoor group to survive? Should I bring them in when it starts getting colder?

Any advice appreciated


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## jolt100 (8 Apr 2019)

I have daphnia in tubs outside in the UK which regularly freeze when we have hard frost , they have been going for over 10 years and the eggs survive even when the adults fade away during the winter . I feed them some yeast occasionally. 
If you want to use them all year you could set up a tank inside just before the winter starts. 
Cheers


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## zozo (8 Apr 2019)

Last/this year we had a pretty mild winter with a minimum of frost only short periodes. And even with occasionaly breaking the few mm ice at the surface i still could catch daphnia. They are more sensitive to heat than they are to cold. They easily survive a -3°C winter.

I have a 80 litre square (cement) tub in the garden for it with leaf litter only i never feed them additionaly. I notice they become less active when its colder, than they sink to the bottom foraging on the leaflitter. Always need to stir the water a bit with the net to disturb the leaflitter substrate and wait for the circulation to spread some over the water column. Than scoop 'm out. Or else you can wait for days looking and never see any.. But they are there on the bottom.. 

When temps rise, the water gets more active, free floating algae starts to appear and the daphnia start foraging free swiming too.


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## TBRO (8 Apr 2019)

As above, I’ve got a large rain butt full of them. Even when frozen on top they were still swimming around. Just break the ice and dip in a net! 

I think the key is using the biggest container you can for all sorts of reasons around stability. 


Sent from my iPhone using Tapatalk


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## zozo (8 Apr 2019)

TBRO said:


> I think the key is using the biggest container you can for all sorts of reasons around stability.



Yup +1.. Absolutely a pre, i've tryed 10 or 15 litre buckets outdoor, they do good a summer and part of the winter, but always crash at one point. Nad it needs a clean and restart..
Small volumes crash to easily.. Minimum of 80 litres does good, if winters are mild.


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## Mike~~ (9 Apr 2019)

Thanks for the advice - I've got very small containers. Maybe 10L. That's why I've set up two in different conditions, so if one crashes then I can clear it and repopulate. Hope that works out.


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## dw1305 (9 Apr 2019)

Hi all, 





Mike~~ said:


> so if one crashes then I can clear it and repopulate. Hope that works out.


Ten litres should be fine. Have a look at the <"dried grass" method"> from Caudata.org, it works really well to stop population "_boom and bust_". 

cheers Darrel


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## tam (9 Apr 2019)

I brought my daphnia inside last autumn, leaving about 1" of water in the bottom of a 10L bucket outside and there were none visible. Over winter it's filled with rain water and and there has been a fresh colony for at least the last couple of weeks. It's still been dropping to about 0/1 oC overnight though we've had 'warm' days of 10-15. If you want to feed over winter I would bring some in, but they'll survive and repopulate in spring when it warms up.


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## zozo (9 Apr 2019)

tam said:


> I brought my daphnia inside last autumn, leaving about 1" of water in the bottom of a 10L bucket outside and there were none visible. Over winter it's filled with rain water and and there has been a fresh colony for at least the last couple of weeks. It's still been dropping to about 0/1 oC overnight though we've had 'warm' days of 10-15. If you want to feed over winter I would bring some in, but they'll survive and repopulate in spring when it warms up.



They hatch extremely small, not rocognizable as daphnia with the naked eye. With the naked eye barely noticable something is moving in a drop of water. Under the microscope it clearly was daphnia to my surprice. I expected to find something different. Than when its colder they don't move that fast, then stiring up some water it looks like tiny specs of debri stired up and caught in the net. Not looking like anything that lives. When temps rise preferably above 20°C than suddenly its a huge colony of happily moving daphnia babies.


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## tam (9 Apr 2019)

zozo said:


> They hatch extremely small, not rocognizable as daphnia with the naked eye. With the naked eye barely noticable something is moving in a drop of water. Under the microscope it clearly was daphnia to my surprice.



Oh, interesting! I didn't realise that. They must have hatched earlier than I thought then as it was near adult sized ones I noticed.


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