Transgenerational inheritance of shuffled symbiont communities in the coral Montipora digitata

To evaluate the effects of El Nino driven mass thermal stress on the coral Monitpora digitata during spawning in a severe bleaching year (2016).32 colonies were collected, from a minimum of 5 - 10 metres apart laterally along the shore. Spawning occurred on 23rd April 2015, where egg-sperm bundles were collected from spawning colonies, total of 9. 27 of these colonies were re-collected from Hazard Bay in April 2016 and 5 remaining colonies were presumed dead. Colony colouration was assessed using the CoralWatch Color Chart, with photographs alongside each colony at the time of collection. Spawning occurred on 24th April 2016, and a total of 4 were spawning colonies.To determine the effects of thermal stress and the presence of bleaching in 2016, the health of coral colonies were measured using methods of effective quantum yield of photosystem II (YII), colony coloration, and Symbiodiniaceae cell density. YII was measured using Pulse Amplitude Modulated fluorometry (PAM) with a fibre optic cable (diving-PAM, Waltz).Samples from all spawning adults and 10 – 12 eggs from each colony were genotyped in both 2015 and 2016 through ITS2 amplicon sequencing. Analysis of community composition was achieved through sequence variations, evidence of shuffling of Symbiodiniaceae communities and differences in Symbiont densities and photochemical efficiencies.

本研究旨在评估厄尔尼诺（El Nino）驱动的大规模热应激，对2016年（严重珊瑚白化年）产卵期的指状牡丹珊瑚（Monitpora digitata）的影响。研究共采集32株珊瑚群落，所有采样点沿海岸横向间距不小于5至10米。2015年4月23日为该海域珊瑚产卵日，研究人员从产卵群落中收集了共计9束精卵结合体。2016年4月，研究人员从哈泽德湾（Hazard Bay）重新采集了其中27株珊瑚群落，剩余5株被推定死亡。采样时同步拍摄每株珊瑚群落的照片，并采用珊瑚观察色卡（CoralWatch Color Chart）评估其着色情况。2016年的产卵日为4月24日，本次共有4株珊瑚群落产卵。为明确2016年热应激与珊瑚白化的影响，研究通过光系统II有效量子产额（effective quantum yield of photosystem II, YII）、珊瑚群落着色情况以及虫黄藻科（Symbiodiniaceae）细胞密度三项指标，评估珊瑚群落的健康状态。其中，光系统II有效量子产额通过脉冲振幅调制荧光仪（Pulse Amplitude Modulated fluorometry, PAM）配合光纤线缆（Waltz品牌潜水式PAM）进行测定。2015年与2016年，研究人员均对所有产卵成体样本以及每株群落的10至12枚卵进行ITS2扩增子测序（ITS2 amplicon sequencing）以完成基因分型。群落组成分析通过序列变异、虫黄藻科群落重组证据以及共生体密度与光化学效率的差异展开。