‘Forgotten conservation targets’: the hidden world of aquatic fungi

Fungi have increasingly captured our imaginations in recent years. Interest in their roles in forming vast underground mycelial ‘wood wide web’ networks, and as the basis for medicines, energy and eco-materials has exploded in the past decade. However, the hidden fungal worlds beneath the surface of freshwaters have, so far, been largely ignored.

A new study asks conservationists and policy makers to urgently turn their attention to the key roles aquatic fungi play in freshwater ecosystems. Its authors highlight how often-invisible aquatic fungi are vital in supporting freshwater food webs, in cycling nutrients, material and energy, and in helping purify water. However, their microscopic roles in underpinning river, lake and wetland ecosystems are mostly neglected in conservation management.

“So far, IUCN Red List of Threatened Species includes assessments for only a small number of fungi, and all of those assessed also comprise only terrestrial macrofungi,” says co-author Mariyana Vatova from the University of the Algarve. “What complicates such assessments is that many groups of aquatic fungi are poorly studied, and many species are yet to be discovered and described.”

The few existing scientific studies on aquatic fungi focus largely on their response to fungicide pollution from agriculture. “However, many other pollutants can affect fungi and their delicate networks, such as pharmaceuticals, metals, microplastics, and nutrient pollution,” says co-author Hans-Peter Grossart from IGB Berlin. “What is even more worrying is that we know almost nothing about the other threats that they are likely facing. Some of the major threats for aquatic fungi include habitat modification and degradation, biological invasions, and climate change.”

These threats can lead to population declines and extinctions in aquatic fungal communities, with potentially harmful cascade effects across the entire freshwater ecosystem. “Unfortunately, due to large gaps in our current knowledge, many such cases are likely to go undetected and remain hidden”, explains co-author Ivan Jarić from the Biology Centre of the Czech Academy of Sciences. “Such cryptic losses of ecosystem functions can aggravate the situation further, by hindering our ability to implement timely and effective conservation measures.”

The authors, in collaboration with the Alliance for Freshwater Life, thus argue that aquatic fungi needs to be urgently recognised as a priority for freshwater conservation and policy. “All such management efforts should aim to both protect fungal diversity, and to maintain their key ecosystem functions,” suggests co-author Susana C. Gonçalves from the University of Coimbra in Portugal, who is also a member of the IUCN SSC Fungal Conservation Committee.

Aquatic fungi management initiatives include reducing pollution, controlling the spread of invasive species, restoring biodiversity habitat and maintaining natural water levels and flows. These are all umbrella measures which can benefit entire freshwater ecosystems, however, the authors argue that they can be tailored to consider the particularities of aquatic fungi populations.

One key task in this process is to develop new bioassay techniques which can help us better understand the role of ecological pressures such as pollution on aquatic fungi. Such measures are critical for the better addressing the overlooked importance of these ‘forgotten conservation targets’.

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Vatova, M., Rubin, C., Grossart, H.P., Gonçalves, S.C., Schmidt, S.I. and Jarić, I. (2022). Aquatic fungi: largely neglected targets for conservation. Frontiers in Ecology and the Environment 20 (4), 207-209.