newts

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newts

Postby Michal Szkudlarek » Wed Jul 12, 2017 10:22 am

Hello
Why are crested newts less common than lissotritons? Are crested newts more demanding regarding habitat? In what sense? You can often find habitats where only lissotriton occurs, no crested newts but the opposite is =rare i think.
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Re: newts

Postby Alexandre Roux » Wed Jul 12, 2017 6:50 pm

Michal Szkudlarek wrote:Hello
Why are crested newts less common than lissotritons? Are crested newts more demanding regarding habitat? In what sense? You can often find habitats where only lissotriton occurs, no crested newts but the opposite is =rare i think.


Here in France (near Lyon), Crested newt (Triturus cristatus) need pretty deep ponds (60 cm as a minimum), generally needs ponds from 50 to 500m² with absolutely NO fish but a lot of aquatic vegetation.
The ponds covered by two-thirds hydrophytes and between a quarter and half of helophytes are particularly adapted. Especially if they have a few open banks, suitable for wedding parades.
It usually occupies stagnant waters oligotrophic or oligo-mesotrophic, rich in salts minerals and plankton.
A pH close to neutrality is preferred even if the newts can withstand PH of 4.4 to 9.5.
You'll only find it near forest where it finds its terrestrial habitat.
Triturus carnifex (introduced around here) seems to be less demanding on all of these parameters.

Still speaking of what we have near Lyon, Lissotriton species can live with fishes if the pond is vegalised enough for them to hide and lay eggs. They can use every kind of pond (every size, even if they're not deep at all). They're also not so exacting about how much vegetation there are. I've seen some laying eggs on plastic bags.

Considering the differences between these species, with such different requirements, you can easily understand why Triturus are not as common as Lissotriton.
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Re: newts

Postby Michal Szkudlarek » Wed Jul 12, 2017 8:16 pm

Alexandre Roux wrote:
Michal Szkudlarek wrote:Hello
Why are crested newts less common than lissotritons? Are crested newts more demanding regarding habitat? In what sense? You can often find habitats where only lissotriton occurs, no crested newts but the opposite is =rare i think.


Here in France (near Lyon), Crested newt (Triturus cristatus) need pretty deep ponds (60 cm as a minimum), generally needs ponds from 50 to 500m² with absolutely NO fish but a lot of aquatic vegetation.
The ponds covered by two-thirds hydrophytes and between a quarter and half of helophytes are particularly adapted. Especially if they have a few open banks, suitable for wedding parades.
It usually occupies stagnant waters oligotrophic or oligo-mesotrophic, rich in salts minerals and plankton.
A pH close to neutrality is preferred even if the newts can withstand PH of 4.4 to 9.5.
You'll only find it near forest where it finds its terrestrial habitat.
Triturus carnifex (introduced around here) seems to be less demanding on all of these parameters.

Still speaking of what we have near Lyon, Lissotriton species can live with fishes if the pond is vegalised enough for them to hide and lay eggs. They can use every kind of pond (every size, even if they're not deep at all). They're also not so exacting about how much vegetation there are. I've seen some laying eggs on plastic bags.

Considering the differences between these species, with such different requirements, you can easily understand why Triturus are not as common as Lissotriton.

thanks for reply but what causes these differences in requirements of those species?
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Re: newts

Postby Will Atkins » Fri Jul 14, 2017 9:37 am

Triturus is bigger than Lissotriton, and so are its larvae. Larvae need more food and take longer to develop compared with Lissotriton, so they need larger ponds. They also hang in the open water (nektonic) to feast on clouds of Daphnia etc. Catch 22 is that bigger ponds and open water mean a higher probability of fish being present, which eat the crested newt larvae. Hence they are walking a tightrope between small ponds that dry out too soon and don't have enough food in them and big ponds that have permanent water and hold predatory fish - even (especially) sticklebacks. The real Q is how any crested newts manage to survive at all - answer - areas of high pond density where metapopulations can form, using a fraction of the ponds that happen to be suitable, or, more rarely, larger ponds without fish such as ephemeral dune ponds, isolated ponds etc.
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Re: newts

Postby Michal Szkudlarek » Fri Jul 14, 2017 12:59 pm

Will Atkins wrote:Triturus is bigger than Lissotriton, and so are its larvae. Larvae need more food and take longer to develop compared with Lissotriton, so they need larger ponds. They also hang in the open water (nektonic) to feast on clouds of Daphnia etc. Catch 22 is that bigger ponds and open water mean a higher probability of fish being present, which eat the crested newt larvae. Hence they are walking a tightrope between small ponds that dry out too soon and don't have enough food in them and big ponds that have permanent water and hold predatory fish - even (especially) sticklebacks. The real Q is how any crested newts manage to survive at all - answer - areas of high pond density where metapopulations can form, using a fraction of the ponds that happen to be suitable, or, more rarely, larger ponds without fish such as ephemeral dune ponds, isolated ponds etc.

thanks for explaination! :) btw are larvas of Triturus species easier to find than Lissotriton larvas?
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Re: newts

Postby Will Atkins » Sat Jul 15, 2017 9:47 am

No problem, happy to help.

Since Triturus larvae float suspended in the water column for long periods they are generally easier to locate from the bank of the pond, especially at night in a torch beam but also by day. Lissotriton are more likely to be hidden in weeds which is why they can survive fish presence better than Triturus. They're quite easy to find in the algae if you're prepared to search for them with nets, fingers etc!
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