Abstract
Little is known about the seasonal dynamic of archaeal communities and their potential ecological functions in temperate seagrass ecosystems. In this study, seasonal changes in diversity, community structure, and potential metabolic functions of benthic archaea in surface sediments of two seagrass meadows along the northern Bohai Sea in China were investigated using Miseq sequencing of the 16S rRNA gene and Tax4Fun2 functional prediction. Overall, Crenarchaeota (mainly Bathy-15, Bathy-8, and Bathy-6) dominated, followed by Thermoplasmatota, Asgardarchaeota, and Halobacterota, in terms of alpha diversities and relative abundance. Significant seasonal changes in the entire archaeal community structure were observed. The major phyla Methanobacteria, Nitrosopumilales, and genus Methanolobus had higher proportions in spring, while MBG-D and Bathyarchaeota were more abundant in summer and autumn, respectively. Alpha diversities (Shannon and Simpson) were the highest in summer and the lowest in autumn (ANOVA test, p < 0.05). Salinity, total organic carbon, and total organic nitrogen were the most significant factors influencing the entire archaeal community. Higher cellulose and hemicellulose degradation potentials occurred in summer, while methane metabolism potentials were higher in winter. This study indicated that season had strong effects in modulating benthic archaeal diversity and functional potentials in the temperate seagrass ecosystems.
Highlights
Seagrass is a globally distributed submerged marine angiosperm and plays a key role in building the coastal ecology that forms a crucial ecotone between marine and terrestrial environments
We addressed the following questions: (i) What is the seasonal distribution pattern of the archaeal community in Z. japonica meadows? (ii) What are the major environmental drivers attributed to the seasonal pattern? (iii) Do seasonal changes affect the stability of archaeal ecological functions? By answering the above questions, we aim to reveal the seasonal dynamic and ecological functions of benthic archaeal communities in seagrass Z. japonica ecosystems
We examined seasonal effects on the diversity, composition, and functional potentials of the archaeal community in seagrass Z. japonica ecosystems
Summary
Seagrass is a globally distributed submerged marine angiosperm and plays a key role in building the coastal ecology that forms a crucial ecotone between marine and terrestrial environments. The microorganisms inhabiting seagrass meadows have essential roles in promoting plant growth by producing auxin, liberating nutrients from OM [9], suppressing pathogens [10,11], and facilitating sulfide detoxification [12]. In such an ecologically important ecosystem, information on less abundant yet crucial archaeal communities remain scarce. The spatial patterns in archaeal distribution have been described for several coastal marine environments, including the Antarctic coastal waters [20], mangrove and intertidal wetland mudflats [21,22], the coast of the North Sea [23], and Shark Bay mats [24]. In contrast to the increasing knowledge gleaned from spatial variations in archaeal communities and their niche preferences, much less is known about archaeal seasonal dynamics and their ecological potentials in seagrass sediments, even though seagrass-associated bacterial and microeukaryotic communities do exhibit distinct seasonal or annual variations [25,26]
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