Nutrient regulated thermal tolerance in corals from the Great Barrier Reef

A 90-day long experiment was conducted to understand the link between turbid nutrient-enriched conditions and elevated temperature condition, and their effects on corals. The objective of the experiment was to determine whether corals exposed to coastal water containing terrestrial runoff and sediment resuspension (nutrient enriched waters) increase protection against or increased sensitivity to the effects of thermal stress. Conditions in the experiment simulated realistic levels of elevated nutrients, sediments and heat stress found on coastal waters.Colonies of two common scleractinian corals (Acropora millepora and Montipora tuberculosa) were collected from inshore reefs of the central Great Barrier Reef. Colony fragments were sourced from 2 - 4 meters depth. Acropora Millepora were sourced from Pelorus Island and Double Cone Islands, and Monitpora tuberculosa were sourced from Magnetic Island. Samples were kept in coastal seawater, or organically and nutrient enriched coastal seawater (OE), and/or enriched with nitrate. Samples were acclimatised for 10 days, before temperature conditions gradually increased from 27°C to 31.2°C. After 3–7 weeks of heat stress, recovery after ending heat stress was also observed up to 31-38 days. Effects on both species were determined and quantified as differences in survival, photophysiological stress and recovery, and skeletal growth rates. This study was jointly funded by the Australian Institute of Marine Science, the Australian Government’s Marine and Tropical Sciences Research Facility, and the Australian Government’s National Environmental Research Program.

为探究浑浊富营养化环境与升温环境之间的关联及其对珊瑚的影响，开展了一项为期90天的实验。该实验的目的是确定：暴露于含陆源径流和沉积物再悬浮的近岸海水（富营养化水体）中的珊瑚，对热胁迫效应的抵抗力是否增强，或是敏感性是否提升。实验条件模拟了近岸海域中真实存在的营养盐升高、沉积物增加及热胁迫水平。

两种常见石珊瑚（scleractinian corals）的群体——多孔鹿角珊瑚（Acropora millepora）和瘤状表孔珊瑚（Montipora tuberculosa）——采集自大堡礁中部的近岸珊瑚礁。珊瑚群体片段取自2-4米水深区域：多孔鹿角珊瑚来自佩洛鲁斯岛（Pelorus Island）和双锥岛（Double Cone Islands），瘤状表孔珊瑚来自磁岛（Magnetic Island）。

样本被置于近岸海水、有机及营养富集的近岸海水（简称OE）、以及/或添加硝酸盐的海水中。样本经过10天驯化后，温度条件从27°C逐步升高至31.2°C。在3-7周的热胁迫处理后，还观测了热胁迫结束后的恢复过程，时长可达31-38天。通过生存状况、光生理胁迫与恢复情况、以及骨骼生长速率的差异，测定并量化了两种珊瑚受到的影响。

本研究由澳大利亚海洋科学研究所（Australian Institute of Marine Science）、澳大利亚政府海洋与热带科学研究设施（Australian Government’s Marine and Tropical Sciences Research Facility）及澳大利亚政府国家环境研究计划（Australian Government’s National Environmental Research Program）联合资助。