Heat-evolved microalgal symbionts increase thermal bleaching tolerance of coral juveniles without a trade-off against growth

This study was designed to test the effect of heat-evolved macroalgal symbionts against bleaching tolerance in juvenile corals in response to a simulated heatwave.Juveniles of the coral Acropora tenuis were infected with either wildtype (WT10) or heat-evolved (SS1 or SS8) strains of the Symbiodiniaceae species Cladocopium C1acro (formerly Cladocopium goreaui 2–4).The juveniles were maintained at ambient conditions (27°C) for 10 months at which time their size was measured. Growth, survival, and metabolism data were collected following a simulated heatwave (31°C for 41 days).Photographs and PSII maximum quantum yields (Fv/Fm) were collected throughout the heat stress period, stable isotope incubation and cell counts were carried out on day 39, and respirometry on days 40-41. Symbiodiniaceae cell densities per juvenile were quantified to assess bleaching.Statistical analyses were run in R and respirometry data was analysed using the respR package.Full methods and technical details are found in the paper https://ssrn.com/abstract=3981099

本研究旨在探究热演化大型藻类共生体对模拟热浪胁迫下幼年珊瑚白化耐受性的影响。实验选取轴孔珊瑚（Acropora tenuis）幼体，分别接种野生型（WT10）与热演化型（SS1或SS8）的虫黄藻科（Symbiodiniaceae）Cladocopium C1acro菌株（原分类学名称为Cladocopium goreaui 2–4）。将幼体置于27℃的常规环境中饲养10个月，随后测量其个体尺寸。在完成31℃持续41天的模拟热浪胁迫后，采集幼体的生长、存活及代谢相关数据。热胁迫期间持续采集幼体照片与PSII最大量子产额（Fv/Fm）；实验第39天开展稳定同位素培养与细胞计数，第40至41天进行呼吸代谢测定。通过量化每株幼体的虫黄藻细胞密度，以评估珊瑚白化程度。本研究的统计分析均基于R语言完成，呼吸代谢数据采用respR数据包进行分析处理。完整的实验方法与技术细节可参阅论文https://ssrn.com/abstract=3981099