DataSheet_1_Effect of seaweed canopy disturbance on understory microbial communities on rocky shores.pdf

IntroductionThe collapse of macroalgal habitats is altering the structure of benthic communities on rocky shores globally. Nonetheless, how the loss of canopy-forming macroalgae influences the structure of epilithic microbial communities is yet to be explored. MethodsHere, we used experimental field manipulations and 16S-rRNA-gene amplicon sequencing to determine the effects of macroalgal loss on the understory bacterial communities and their relationship with epiphytic bacteria on macroalgae. Beds of the fucoid Hormosira banksii were exposed to different levels of disturbance resulting in five treatments: (i) 100% removal of Hormosira individuals, (ii) 50% removal, (iii) no removal, (iv) a procedural control that mimicked the removal process, but no Hormosira was removed and (v) adjacent bare rock. Canopy cover, bacterial communities (epilithic and epiphytic) and benthic macroorganisms were monitored for 16 months.ResultsResults showed that reductions in canopy cover rapidly altered understory bacterial diversity and composition. Hormosira canopies in 50% and 100% removal plots showed signs of recovery over time, but understory epilithic bacterial communities remained distinct throughout the experiment in plots that experienced full Hormosira removal. Changes in bacterial communities were not related to changes in other benthic macroorganisms.DiscussionThese results demonstrate that understory epilithic bacterial communities respond rapidly to environmental disturbances at small scales and these changes can be long-lasting. A deeper knowledge of the ecological role of understory epilithic microbial communities is needed to better understand potential cascading effects of disturbances on the functioning of macroalgal-dominated systems.

引言：全球范围内，大型藻类栖息地的崩溃正在改变岩石海岸底栖群落的结构。然而，冠层形成的大型藻类的丧失如何影响附生微生物群落的结构，这一课题尚待深入研究。方法：在本研究中，我们通过实验性田间操作和16S-rRNA基因扩增子测序，确定了大型藻类丧失对底层细菌群落及其与附生细菌关系的影响。Hormosira banksii藻床暴露于不同水平的扰动中，产生了五种处理方式：（i）100%去除Hormosira个体，（ii）50%去除，（iii）无去除，（iv）模拟去除过程的过程控制，但未去除任何Hormosira，以及（v）相邻裸岩。在16个月内，对冠层覆盖率、细菌群落（附生和附生）以及底栖大型生物进行了监测。结果：结果显示，冠层覆盖率的减少迅速改变了底层细菌的多样性和组成。在50%和100%去除的样地中，Hormosira冠层随着时间的推移显示出恢复的迹象，但在经历完全去除Hormosira的样地中，底层附生细菌群落在整个实验过程中保持独特。细菌群落的变化与底栖大型生物的变化无关。讨论：这些结果证明，底层附生细菌群落对小型尺度上的环境扰动反应迅速，这些变化可能具有长期性。为了更好地理解扰动对大型藻类主导系统功能潜在的级联效应，我们需要更深入地了解底层附生微生物群落的生态作用。