Spatio-temporal Patterns Of Fungi And Fungus-like Protist In Coastal Waters

Fungi and fungus-like protist are acknowledged to play important roles in biogeochemical cycles.Although evidences suggest that they widely occur in marine environments,little is known about their distribution patterns in coastal waters.In order to explore the temporal and spatial patterns of fungal communities in coastal waters and the associated environmental drivers,we used 18S rRNA gene fragment abundance and the sequence of rRNA operon internal transcribed spacer(ITS)to explore the dynamics of fungal community in temperate coastal waters through both time-series and transect studies.The results of time series study showed that the diversity,abundance and community composition of fungal community exhibited prominent seasonality:the 18S rRNA gene fragment abundance peaked during summer and fall,showing positive correlations with chlorophyll a,SiO₄ and oxygen saturation;diversity was highest during winter and lowest during summer,and it significantly responded to temperature,pH,chlorophyll a,insolation,salinity,and DIC;fungal community ITS libraries were dominated throughout the year by Ascomycota,with contributions from Basidiomycota,Chytridiomycota and others,with their seasonal dynamics linked to water temperature,light,and the carbonate system.The results of transect study showed that fungal abundance decreased gradually from nearshore to offshore;and their diversity was dynamic from nearshore to offshore,with the lowest diversity occurring in between the nearshore and offshore;the spatial variations in both abundance and diversity were significantly correlated with dissolved inorganic carbon and salinity;each station contained not only common but also unique taxa.The farther was the distance between two stations,the less was the number of the shared taxa.Flow cytometry was used to explore the temporal and spatial patterns of fungus-like protist abundance in coastal waters,the results showed that they were more abundant in summer than in spring;their abundance at most of nearshore stations was higher than that at offshore stations;and the biomass of fungus-like protist at some stations was higher than that of bacteria.Overall,our findings highlighted the importance of fungi and fungus-like protist in coastal marine ecosystem.