Spatial and temporal patterns of aquatic fungi inside and outside protected areas in Northern Portugal

Aquatic fungi (AF) are key contributors to freshwater ecosystem health, functioning, and resilience. Yet, they have been almost entirely neglected in all major global conservation plans and policies. The FUNACTION project addresses this gap by building the first comprehensive knowledge base on the diversity of AF at a pan-European scale. This case study aimed to assess the effectiveness of protected areas (PA) in conserving AF and to explore the spatial and temporal patterns of AF diversity and distribution. Fifty-four sites located in two PA in northern Portugal were surveyed between November and December 2023: 24 sites in Peneda-Gerês National Park – PGNP (12 inside and 12 outside the PA) and 30 sites in Montesinho Nature Park - MNP (15 inside and 15 outside the PA). Additionally, a subset of 6 sites inside and outside PGNP were surveyed every season until October 2024. Water samples were filtrated to collect AF conidia and their morphological identification was performed. In a preliminary analysis, only about 30% of the morphotypes could be identified to species or genus level, underscoring a major knowledge gap in aquatic fungal taxonomy. Regarding the spatial patterns, AF richness was higher for MNP than PGNP, but there was no difference between sites inside or outside the PA. Forty-five taxa co-occurred in both PA, but 36 and 38 occurred only at PGNP and MNP, respectively. Interestingly, 5 morphotypes occurred only outside PGNP and 22 only outside MNP. Regarding temporal patterns, species richness and conidia concentration varied across streams and seasons, but not between state of protection. Autumn presented the highest values of richness and conidia concentrations, aligning with leaf fall and increased carbon availability. Overall, this study highlights 1) the need to better understand AF species distribution, and the potential threats to taxa occurring only outside PA; 2) the fact that AF communities changed seasonally and this should be taken into account when planning their monitoring; and 3) that the existing PA do not seem to be effective in promoting higher AF diversity and consequently there is an urgent need to include AF in conservation planning.