Antarctic Glacial Meltwater Impacts the Diversity of Fungal Parasites Associated With Benthic Diatoms in Shallow Coastal Zones

Abstract

Aquatic ecosystems are frequently overlooked as fungal habitats, although there is increasing evidence that their diversity and ecological importance are greater than previously considered. Aquatic fungi are critical and abundant components of nutrient cycling and food web dynamics, e.g., exerting top-down control on phytoplankton communities and forming symbioses with many marine microorganisms. However, their relevance for microphytobenthic communities is almost unexplored. In the light of global warming, polar regions face extreme changes in abiotic factors with a severe impact on biodiversity and ecosystem functioning. Therefore, this study aimed to describe, for the first time, fungal diversity in Antarctic benthic habitats along the salinity gradient and to determine the co-occurrence of fungal parasites with their algal hosts, which were dominated by benthic diatoms. Our results reveal that Ascomycota and Chytridiomycota are the most abundant fungal taxa in these habitats. We show that also in Antarctic waters, salinity has a major impact on shaping not just fungal but rather the whole eukaryotic community composition, with a diversity of aquatic fungi increasing as salinity decreases. Moreover, we determined correlations between putative fungal parasites and potential benthic diatom hosts, highlighting the need for further systematic analysis of fungal diversity along with studies on taxonomy and ecological roles of Chytridiomycota.

Co-occurrences enhance our understanding of aquatic fungal metacommunity assembly and reveal potential host–parasite interactions

“…Besides the major impact of salinity in shaping fungal communities (Rojas-Jimenez et al 2019 , Ilicic et al 2022 ), our results highlight the relevance of other abiotic factors (i.e. temperature, pH, humic substances, etc.)…”

“…In addition to distribution models, network approaches have been applied successfully to reveal detailed biotic associations. Such methods were proven to predict host–parasite interactions in virus- and chytrid-focused studies (Rojas-Jimenez et al 2017 , Kilias et al 2020 , Meng et al 2021 , Ilicic et al 2022 ) as well, even if network inference needs to be taken cautiously. Nevertheless, application of network approaches can help us to extend current knowledge on the relationships of fungi with other microorganisms (Rojas-Jimenez et al 2017 ).…”

Co-occurrences enhance our understanding of aquatic fungal metacommunity assembly and reveal potential host–parasite interactions

“…Besides the major impact of salinity in shaping fungal communities (Rojas-Jimenez et al 2019, Ilicic et al 2022), our results highlight the relevance of other abiotic factors (i.e., temperature, pH, humic substances, etc.) as well as the influence of time in affecting community dynamic of mycoplankton.…”

“…To overcome this issue, probabilistic graphical model-based network approaches have been proven to successfully deal with indirect associations (as a result of shared environmental niches) by the incorporation of environmental metadata (Tackmann et al 2019, Matchado et al 2021). By revealing co-occurrences, networks have recently been useful to predict host–parasite interactions in virus- and chytrid-focused studies (Rojas-Jimenez et al 2017, Kilias et al 2020, Meng et al 2021, Ilicic et al 2022), even if network inference needs to be taken cautiously. Nevertheless, application of network approaches can help us to extend current knowledge on the relationships of fungi with other microorganisms (Rojas-Jimenez et al 2017).…”

Metatranscriptomics and metabarcoding reveal spatiotemporal shifts in fungal communities and their activities in Chinese coastal waters

“…There is increasing evidence from molecular surveys of microbial diversity that chytrids may be quite abundant in cool waters. For example, next‐generation approaches highlighted the non‐trivial occurrence of Chytridiomycota in polar waters (Comeau et al, 2016; Hassett et al, 2019; Hassett & Gradinger, 2016; Ilicic et al, 2022; Kilias et al, 2020). High representation of chytrids was detected in the cold‐water mass in both ITS amplicon and mRNA data, and it remains an open question in Yellow Sea (and other marine habitats), whether Chytridiomycota proliferate due to lower temperatures, higher salinities, increasing phytoplankton abundance, presence of specific ions (e.g., Ca 2+ ), or a combination of all or some of these variables.…”