Human activities alter ecosystems and in most cases lead to biodiversity loss. Animals, plants and fungi are responsible for ecosystems' processes and services. The loss of species threatens the ability of ecosystems to provide these services and to remain stable over time.
Scientists have raised awareness of this threat for decades and in response, policy has established biomonitoring programs that help to assess change in ecosystem status and biodiversity over time and space. However, despite their importance for ecosystems, no monitoring program yet includes aquatic fungi, i.e. fungi living in freshwater and marine ecosystems. Understanding and monitoring the biodiversity, functions, ecological roles, and ecosystem services of aquatic fungi requires diverse techniques and approaches to be efficient, ranging from traditional morphology-based to novel molecular and biochemical techniques and from in-situ observations and experiments to remote sensing approaches. It will also require better coordination among scientists, conservationists, and ecosystem managers globally to implement techniques most effectively.