Experiment results

In this topic (http://www.caudata.org/forum/messages/13/34261.html?1119462517) I wrote about a pseudo-experiment I was conducting with cynops orientalis. Because I got similar results with pleurodeles waltl I thought I bring it up in the general discussion part of the forum.

What I did:
cynops: 2 orientalis larves were kept outside in a plastic box, but except being outside there wasn't much different for those inside.
pleuro's: 1 pleuro larve was only 1/3 in size of his equally old brothers/sisters. Because canibalism already had happened I took him apart and placed him outside.

The cynops were outside during spring, the pleuro's during summer.

Findings:
cynops: the two outside were placed inside before morfing. All cynops morfed within a month (but mind that they were not all equally old). The two 'outsiders' were bigger in size when they morfed than the ones that stayed indoors. Also, they hardly spend any time on the small island I provide them. They went back into the water within a week. Some of the other indoor morfs are at present still on that island (but also eat in the water). Because they are in the water all the time I think they also eat more which increases the size difference. This week I took this picture. The two outsiders are equally big. I placed one of them next to the biggest indoor morf.



I have now placed them in separate tanks.

pleuro's: the one that was 1/3 in size grew equally big in size as his brothers/sisters. Also, however he's as big as his siblings that morfed over a month ago, he still didn't. This supports the idea that he will morf at a bigger size as well.

Conclusion:
The main difference between in- and outdoor setups is the temperature. Inside temperatures don't go up and down during night/day as much as they do outside. Maybe colder nights outside save energy for the newts to put in growing?
I'm not so sure the outside newts had more access to (micro)food than the ones inside - in fact I sometimes forgot to feed the ones outside.

What are your thoughts?

Joeri

Hi Joeri,

Did you take any temperature measurements in the outdoor container(s)? And how larger were the containers?

I think there could be a lot of advantages in raising larvae outdoors: (1) a container that has aged outdoors is full of microfood, and supplies a much greater VARIETY of food items. (2) Natural microfoods are fresher, perhaps more nutritious. (3) In most climates, the temperature cools down at night, which is beneficial. (4) The water quality may be better, due to abundant algae, micro-life, and rain water.

Of course, there are risks too. Flooding during heavy rainfall. Outdoor predators. Escape after morph. Overheating. Small mammals falling in and drowning (this happened to me in a daphnia tub).

Based on your experience, I am intrigued enough to try outdoor rearing next spring. Particularly if I get an overabundance of eggs.

Hey Jen,

As far as water quality goes and microorganisms: I have a large tub pond in my balcony garden and it is usually filled with all manner of invertebrates from parameciums to slaters. It receives morning sun but is shaded during mid-day Night temperatures here are currently 16-19ºC in the day and drops to 11ºC at night. The plants within the pond are elodea densa and pygmy waterlilies.

Flooding is checked by a small side valve which is netted, the only possible predator would be marshland birds ( herons, though they hardly come here); chances of small mammals falling in are close to nil since I live on the first floor. Shrews and hedgehogs usually forage in the field on the ground floor.

I was wondering if this would be suitable to raise a small batch/ colony of newts during spring? If so the only minor alteration i need is to enclose the pond in a sort of netting to prevent escapees.

Sorry Jen,

I didn't measure temperatures but I expect it to have been around 23°C. But also you are mistaking my outdoor setups. I'll just go by your numbered benefits if you don't mind:

4) The plastic container they were in didn't age. It was the same water as inside. However in both outdoor setups there was a small opening for some rain water to come in.

1) Microfood couldn't have been more available outdoors as I gave microfood both inside as outside. Also I don't see how extra microfood could have gotten in. The cynops were in a plastic tank in which the opening was closed with a screen (is that correct?).
However maybe algae/microfood also grows faster (and reproduces) outside.

I agree with 2 and 3. What's more concerning temperatures is that inside it gets warm during summer where the tanks outside were in the shelter all day.

Joeri

Terry, it sounds feasible. I think you should try. Maybe if you have extra eggs?

Joeri, even though both indoor and outdoor larvae had constant food, I think that the greater abundance of smaller food (or perhaps varied food) outdoors may cause the larvae to eat more. Just a guess.

Maybe I should cruel enough not to feed them, if the don't die there's micro food as you say

Anyway, I'm going to work out this outdoor method next year after we moved. I hope I can settle a bit before the eggs are being laid.