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.
Armillaria novae-zelandiae
Fungi in the genus "Armillaria" have a wide host range and can cause disease on a variety of tree species throughout New Zealand; particularly in plantations, home gardens, and parks. According to Hood (1989) the fungus has also been reported in Chile, Argentina, and Australia. There have also been reported epidemics of kiwifruit orchards. "Armillaria novae-zelandiae" occurs in indigenous forests as a decay fungus of dead trees, stumps, and logs. It causes butt rots in living trees as well. Plants at both the seedling and adult stages are susceptible. Infection happens on the roots of the host plant. The hyphae, mycelium, and rhizomorphs of "A. novae-zelandiae" can survive on infected tissues in soil for a long time, and in spring when plants start growing, the pathogen can infect new growing tissue.