Current rates of ocean warming are predicted to exacerbate ongoing declines in seagrass populations. Above-ground responses of seagrass to increasing temperatures have been studied from a direct physiological perspective while indirect effects, including changes to microbially-mediated below-ground processes, remain poorly understood. To test potential effects of increased temperature on seagrass growth and associated microbial communities, we sampled seagrass beds experiencing ambient and elevated water temperatures at Lake Macquarie, Australia. Sites with warmer water were associated with a plume from a power station discharge channel with temperatures analogous to conditions predicted by 2100 under current rates of ocean warming (+3°C). The microbial community composition in both sediments and leaf tissues varied significantly between warm and ambient water temperatures with higher relative abundances of putative sulphate-reducing bacteria such as Desulfocapsaceae, Desulfobulbaceae and Desulfosarcinaceae in sedimentary communities in warm water. Above-ground biomass and seagrass growth rates were greater at warm sites while below-ground biomass and detrital decomposition rates showed no difference suggesting potential buffering of temperature effects below-ground. These findings suggest a 3°C rise in temperate regions is unlikely to induce mortality in seagrass however, it may shift microbial communities towards more homogenous structure and composition.

中文翻译：

---

随着温度升高，海草床的地上和地下细菌群落发生变化

目前的海洋变暖速度预计将加剧海草种群的持续下降。人们从直接的生理角度研究了海草对温度升高的地上反应，而间接影响，包括微生物介导的地下过程的变化，仍然知之甚少。为了测试温度升高对海草生长和相关微生物群落的潜在影响，我们对澳大利亚麦觉理湖经历环境温度和升高水温的海草床进行了采样。水温较高的地点与来自发电站排放通道的羽流相关，其温度类似于根据当前海洋变暖速度（+3°C）预测的 2100 年的情况。沉积物和叶子组织中的微生物群落组成在温暖水温和环境水温之间存在显着差异，推定的硫酸盐还原细菌的相对丰度较高，例如脱硫辣椒科、脱硫球茎科和脱硫八叠球菌科存在于温水中的沉积群落中。温暖地区的地上生物量和海草生长率较高，而地下生物量和碎屑分解率没有差异，表明地下温度影响的潜在缓冲。这些发现表明，温带地区气温升高 3°C 不太可能导致海草死亡，但可能会使微生物群落的结构和组成变得更加均质。