Newt
Newts, as with salamanders in general and other amphibians, serve as bioindicators because of their thin, sensitive skin and evidence of their presence (or absence) can serve as an indicator of the health of the environment. Most species are highly sensitive to subtle changes in the pH level of the streams and lakes where they live. Because their skin is permeable to water, they absorb oxygen and other substances they need through their skin. Scientists study the stability of the amphibian population when studying the water quality of a particular body of water.
Smooth newt
In the UK, the smooth newt is protected under Schedule 5 of the Wildlife and Countryside Act 1981 with respect to sale only. It is therefore illegal to sell individuals of the species, but their destruction or capture is still permitted. They are also listed under Annex III of the Bern Convention.
The smooth newt is the only newt native to Ireland, and it is protected there under the Wildlife Acts (1976 and 2000). It is an offence to capture or kill a newt in Ireland without a licence.