Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.
Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, 510006, China.
J Environ Manage. 2024 Nov;370:122486. doi: 10.1016/j.jenvman.2024.122486. Epub 2024 Sep 14.
Microorganisms in the sediment play a pivotal role in the functioning and stability of seagrass ecosystems and their dynamics are influenced by the nutrient acquisition strategies of host plants. While the distinct impacts of microbial generalists and specialists on community dynamics are recognized, their distribution patterns and ecological roles within seagrass ecosystems remain largely unexplored. To address this issue, we conducted an analysis of community assembly processes and co-occurrence relationships of both microbial generalists and specialists within sediment profiles (0-100 cm) from seagrass habitats subjected to differing land use conditions. The results revealed that seagrasses in Yifeng Estuary experienced the large proportion of cultivated land and exhibited higher organic carbon content in the 0-20 cm surface sediment layer. Nitrogen-cycling bacteria were predominantly associated with seagrasses from Yifeng Estuary, whereas Vibrio spp. was more prevalent in seagrasses from Liusha Bay. Notably, seagrass Halophia beccarii (YHB) in Yifeng Estuary harbored higher niche breadths for both microbial generalist and specialist compared to Halodule uninervis (LHU) and Halophia ovalis (LHO) from Liusha Bay. Stochastic processes were pivotal in shaping seagrass sediment microbial communities, with a higher immigration rate observed in YHB, suggesting greater microbial turnover in this area. Additionally, YHB sediment presented lower drift and higher dispersal limitation among generalists compared to LHU and LHO, whereas the pattern was reversed among specialists. Specialists were found to play a crucial role in shaping microbial interactions within YHB sediment, with genera Halioglobus identified as keystone species in the network. The specialists were further found to significantly influence microbial β-diversity in seagrass sediment directly. Overall, our findings illustrated how microbial generalists and specialists were distributed in seagrass sediments in response to land use changes and provided new insights into the potential roles of microbial regulation in degraded seagrass ecosystems.
沉积物中的微生物在海草生态系统的功能和稳定性中发挥着关键作用，其动态受宿主植物获取营养策略的影响。虽然人们已经认识到微生物广义种和狭义种对群落动态的不同影响，但它们在海草生态系统中的分布模式和生态作用在很大程度上仍未得到探索。为了解决这个问题，我们分析了在受不同土地利用条件影响的海草生境的沉积物剖面（0-100 cm）中微生物广义种和狭义种的群落组装过程和共同发生关系。结果表明，义丰河口的海草受到大量耕地的影响，在 0-20 cm 表层沉积物中表现出较高的有机碳含量。氮循环细菌主要与义丰河口的海草有关，而弧菌属（Vibrio spp.）则在流沙湾的海草中更为普遍。值得注意的是，与来自流沙湾的尖瓣海莲（Halodule uninervis，LHU）和海杧果（Halophytum ovalis，LHO）相比，义丰河口的尖瓣海莲（Halophia beccarii，YHB）中微生物广义种和狭义种的生态位宽度都更高。随机过程在塑造海草沉积物微生物群落方面起着关键作用，在 YHB 中观察到更高的迁入率，表明该区域的微生物周转率更高。此外，与 LHU 和 LHO 相比，YHB 沉积物中的广义种具有更低的漂流和更高的扩散限制，而狭义种的模式则相反。研究发现，狭义种在塑造 YHB 沉积物中的微生物相互作用方面起着至关重要的作用，其中 Halioglobus 属被确定为网络中的关键种。进一步发现，狭义种直接显著影响海草沉积物中的微生物 β多样性。总的来说，我们的研究结果说明了微生物广义种和狭义种如何响应土地利用变化分布在海草沉积物中，并为微生物调节在退化海草生态系统中的潜在作用提供了新的见解。
