The number of natural water bodies in which we can research the interactions of organisms with their environment is decreasing on a global level. The discovery of the so-called new species, especially in the caddis fly community, are a contribution to the global biodiversity. Another important contribution was the confirmation of the hypothesis on longitudinal changing of environmental variables even on smaller streams and to realise that an integral evaluation of the state of a water ecosystem requires representative subsamples even from short segments of rivers where the hydrological conditions change rapidly. DNA image cytometry has been standardised and accepted as one of the methods for determination of plant genome size. We have discovered a surprising species diversity of some animal groups in the preserved forests of southern Slovenia. The west part of the Bakan peninsula is one of important European habitats of many invertebrate and vertebrate species. The finding of new chilipode species contributes to the existing knowledge about this animal group which is vital for the functioning of temperate forest ecosystems. The study of Felis silvestris enabled us to determine their patterns of activity, territorial distribution and the basic charasteristics of their social organisation. The need for a more effective protection of this species is becoming a priority all over Europe. Among the plant species of the genus Thlaspi there are many hyperaccumulators of Cd and Zn. The research on the hyperaccumulation of these species is important for their use in phytoremediation. The discovery of micorrhizal symbiosis as a biotechnological method used for improvement of plant growth is therefore important for science as well as for potential use in phytoremediation. The use of micorrhiza for bioindication of polluted sites is also of great biotechnological importance.