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.
Newt fencing
The great crested newt "Triturus cristatus" is an amphibian native to the UK but also widespread across Northern Europe. Whilst it is relatively widespread in the UK (in fact the UK hosts one of the great crested newt's most significant populations), it is rare on a European wide basis. The great crested newt is listed as a "strictly protected fauna species" under appendix II of the Convention on the Conservation of European Wildlife and Natural Habitats:
and consequently is protected under UK legislation through the Wildlife and Countryside Act and the Conservation (Natural Habitat) regulations 1994. Under these regulations it is an offence to intentionally disturb, injure or kill any great crested newt, or disturb or destroy its habitat. Likewise, the Habitats Regulations 2010 do not apply to all newts, and in the case of e.g. smooth newt species, they are protected differently, under the Wildlife and Countryside Act 1981 (as amended).