Beatty Deanna S, Clements Cody S, Stewart Frank J, Hay Mark E
School of Biological Sciences and Aquatic Chemical Ecology Center Georgia Institute of Technology, Atlanta, GA 30332-0230.
Mar Ecol Prog Ser. 2018;589:97-114. doi: 10.3354/meps12465. Epub 2018 Feb 23.
Tropical reefs are shifting from coral to macroalgal dominance, with macroalgae suppressing coral recovery, potentially via effects on coral microbiomes. Understanding how macroalgae affect corals and their microbiomes requires comparing algae- versus coral-dominated reefs without confounding aspects of time and geography. We compared survival, settlement, and post-settlement survival of larvae, as well as the microbiomes of larvae and adults, of the Pacific coral between an Marine Protected Area (MPA) dominated by corals versus an adjacent fished area dominated by macroalgae. Microbiome composition in adult coral, larval coral, and seawater did not differ between the MPA and fished area. However, microbiomes of adult coral were more variable in the fished area and Vibrionaceae bacteria, including strains most closely related to the pathogen , were significantly enriched, but rare, in adult and larval coral from the fished area. Larvae from the macroalgae-dominated area exhibited higher pre-settlement mortality and reduced settlement compared to those from the coral-dominated area. Juveniles planted into a coral-dominated area survived better than those placed into a fished area dominated by macroalgae. Differential survival depended on whether macroalgae were immediately adjacent to juvenile coral rather than on traits of the areas . Contrary to our expectations, coral microbiomes were relatively uniform at the community level despite dramatic differences in macroalgal cover between the MPA (2% cover) and fished (90%) area. Reducing macroalgae may elicit declines in rare but potentially harmful microbes in coral and their larvae, as well as positive intergenerational effects on offspring survival.
热带珊瑚礁正从以珊瑚为主导转变为以大型藻类为主导，大型藻类可能通过影响珊瑚微生物群来抑制珊瑚的恢复。要了解大型藻类如何影响珊瑚及其微生物群，需要比较以藻类为主和以珊瑚为主的珊瑚礁，同时避免时间和地理因素的干扰。我们比较了太平洋珊瑚在以珊瑚为主的海洋保护区（MPA）和相邻以大型藻类为主的捕捞区中幼虫的存活、附着以及附着后的存活情况，以及幼虫和成虫的微生物群。MPA和捕捞区之间成年珊瑚、幼虫珊瑚和海水中的微生物群组成没有差异。然而，捕捞区成年珊瑚的微生物群更具变异性，包括与病原体最密切相关的菌株在内的弧菌科细菌在捕捞区成年和幼虫珊瑚中显著富集，但数量稀少。与来自以珊瑚为主的区域相比来自以大型藻类为主的区域幼虫表现出更高的附着前死亡率和附着率降低。移植到以珊瑚为主区域中的幼体比移植到以大型藻类为主的捕捞区中的幼体存活得更好。幼体的差异存活取决于大型藻类是否紧邻幼体珊瑚，而不是区域的特征。与我们的预期相反，尽管MPA（覆盖率约2%）和捕捞区（覆盖率约90%）之间大型藻类覆盖存在巨大差异，但珊瑚微生物群在群落水平上相对均匀。减少大型藻类可能会导致珊瑚及其幼虫中罕见但潜在有害微生物数量下降，以及对后代存活产生积极代际效应。
