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Increasing evidence suggests that fungal communities are key components of biogeochemical cycles in coastal ecosystems. However, at a regional scale, the major drivers of the seasonal and spatial distribution of fungi in areas impacted by mariculture remain largely unknown. Intensive aquaculture takes place in Dongshan Bay of Fujian, China, a typical subtropical marine ecosystem with multiple environmental gradients extensively perturbed by anthropogenic activities. To better understand the consequences of mariculture on fungal community composition and activities, we simultaneously evaluated the temporal (four different seasons) and spatial dynamics in total (DNA) and active (RNA) fungal communities of Dongshan Bay in relation to several major physicochemical properties. Our results revealed that fungal communities in the Bay were highly diverse, but showed the ubiquitous dominance of Dikarya and the occasional predominance of Glomeromycota, Mucoromycota, Mortierellomycota, Chytridiomycota, Olpidiomycota, and Rozellomycota. Fungal diversity varied much more with season than with the degree of aquaculture activity, for both total and active communities. This notion is supported by co‐occurrence networks exhibiting a clear seasonal pattern. Furthermore, fungal community structure in coastal waters showed distinct relationships with environmental factors varying both with season and in space. For both total and active fungal communities, a combination of environmental variables including temperature, dissolved oxygen, and nitrite exhibited the greatest impact on community structure. Our study demonstrates a distinct spatiotemporal dynamics of both total and active fungi and provides a foundation to better understand the ecological roles of marine fungi in coastal ecosystems in relation to mariculture activities. [ABSTRACT FROM AUTHOR]

Use of aerobic denitrifying consortia, as a new efficient tool for nitrogen removal, has attracted widespread attention because of their stable and efficient nitrogen removal ability. Yet, little attention has been given to highly efficient aerobic denitrifying consortia from mariculture environments. In this study, a natural aerobic denitrifying consortium, named C3, was obtained by an enrichment technique from a coastal mariculture area of Dongshan Bay of Fujian Province, China. In culture, it exhibited good and stable nitrate removing performance. Nitrogen mass balance indicated that 49.30% of the initial TN was converted into gaseous nitrogen and 49.63% was assimilated to biomass nitrogen. High-throughput sequencing and network analysis revealed that Pseudomonas and Fusarium were putative dominant aerobic denitrifying bacterial and fungal species, respectively, cooperating with Exophiala , Penicillium , Mortierella , Neocamarosporium , Neocosmospora , Sterigmatomyces , Thelebolus , Thermomyces , Cutaneotrichosporon and Gymnopilus to perform aerobic denitrification. In addition, four Pseudomonas strains have been successfully isolated from consortium C3, which supported the inference that Pseudomonas was the dominant contributor in the aerobic denitrifying consortium C3. These results will offer novel insights into aerobic denitrifying consortia in mariculture environments for biotechnological nitrogen pollution removal. • An aerobic denitrifying consortium C3 was screened through sub-cultures. • NO 3 − and TN removal efficiencies of C3 could reach 99.14% and 49.30%, respectively. • NO 3 − removal pathways of C3 were demonstrated by nitrogen mass balance. • Potential microbial cooperative interactions drove the nitrate removal process. • Dominant contribution of Pseudomonas in C3 was supported by the isolation of single strains. [ABSTRACT FROM AUTHOR]