In coral reefs and adjacent seagrass meadow and mangrove environments, short temporal scales (i.e. tidal, diurnal) may have important influences on ecosystem processes and community structure, but these scales are rarely investigated. This study examines how tidal and diurnal forcings influence pelagic microorganisms and nutrient dynamics in 3 important and adjacent coastal biomes: mangroves, coral reefs, and seagrass meadows. We sampled for microbial (Bacteria and Archaea) community composition, cell abundances and environmental parameters at 9 coastal sites on St. John, US Virgin Islands that spanned 4 km in distance (4 coral reefs, 2 seagrass meadows and 3 mangrove locations within 2 larger bays). Eight samplings occurred over a 48 h period, capturing day and night microbial dynamics over 2 tidal cycles. The seagrass and reef biomes ex hibited relatively consistent environmental conditions and microbial community structure but were dominated by shifts in picocyanobacterial abundances that were most likely attributed to diel dynamics. In contrast, mangrove ecosystems exhibited substantial daily shifts in environmental parameters, heterotrophic cell abundances and microbial community structure that were consistent with the tidal cycle. Differential abundance analysis of mangrove-associated microorganisms revealed enrichment of pelagic oligotrophic taxa during high tide and enrichment of putative sediment-associated microbes during low tide. Our study underpins the importance of tidal and diurnal time scales in structuring coastal microbial and nutrient dynamics, with diel and tidal cycles contributing to a highly dynamic microbial environment in mangroves, and time of day likely contributing to microbial dynamics in seagrass and reef biomes.

中文翻译：

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潮汐和昼夜时间尺度上红树林、珊瑚礁和海草水域的微生物和营养动态

在珊瑚礁和邻近的海草草甸和红树林环境中，短时间尺度（即潮汐、昼夜）可能对生态系统过程和群落结构有重要影响，但这些尺度很少被研究。本研究考察了潮汐和昼夜强迫如何影响 3 个重要的相邻沿海生物群落中的远洋微生物和营养动态：红树林、珊瑚礁和海草草甸。我们在美属维尔京群岛圣约翰的 9 个沿海地点采样微生物（细菌和古细菌）群落组成、细胞丰度和环境参数，这些地点跨越 4 公里的距离（4 个珊瑚礁、2 个海草草地和 2 个较大的区域内的 3 个红树林位置）。海湾）。在 48 小时内进行了 8 次采样，捕获了 2 个潮汐周期的昼夜微生物动态。海草和珊瑚礁生物群落表现出相对一致的环境条件和微生物群落结构，但主要是微蓝细菌丰度的变化，这很可能归因于饮食动态。相比之下，红树林生态系统在环境参数、异养细胞丰度和微生物群落结构方面表现出与潮汐周期一致的显着每日变化。红树林相关微生物的差异丰度分析揭示了高潮期间远洋寡营养类群的富集和低潮期间推定的沉积物相关微生物的富集。我们的研究证实了潮汐和昼夜时间尺度在构建沿海微生物和营养动态方面的重要性，