Besides global warming, coral reefs face various anthropogenic threats, including watershed-based and marine-based contaminants. Recently, Irgarol 1051, a photosystem II herbicide, has been introduced as a “booster” agent in copper-based antifouling paints after global ban of tributyltin (TBT) in January 2008. Irgarol is considered to pose a potential risk to corals. In this study, a clone of Acropora tenuis separated from the colony collected from Sesoko Island, Okinawa, southern Japan, was exposed to 1.0 $\mathrm{\mu }$g L⁻¹ Irgarol at 27.5 °C and 30.0 °C (higher than the temperature in the warmest month in southern Japan) for 7 d. The coral colour was converted to RGB values, ranging from 0 (darkest) to 255 (brightest). The RGB values under both temperature treatments slightly decreased in the control (no herbicide exposure), but those in both 27.5 °C and 30.0 °C Irgarol treatments increased after day 3. The maximum effective quantum yield ($\Delta$F/${\mathit{F}}_{\mathrm{m}}$′) slightly increased in both 27.5 °C and 30.0 °C control treatments, but decreased in 27.5 °C and 30.0 °C Irgarol treatments after day 1. The exposure to 1.0 $\mathrm{\mu }$g L⁻¹ Irgarol induced significant differences in RGB values and $\Delta$F/${\mathit{F}}_{\mathrm{m}}$′ compared with those in the control at the same temperature. Regarding the temperature difference (27.5 °C vs. 30.0 °C), no significant differences in RGB values and $\Delta$F/$F_{\mathrm{m}}$′ were detected in both control and Irgarol treatments. Our results revealed no significant combined effect of Irgarol exposure and 30.0 °C on A. tenuis. These findings suggest that 30.0 °C is a normally inhabitable environmental temperature for A. tenuis. The bleaching of A. tenuis is more likely caused by the exposure to 1.0 $\mathrm{\mu }$g L⁻¹ Irgarol than by the exposure to high seawater temperature of 30.0 °C.

除了全球变暖，珊瑚礁还面临着各种人为威胁，包括流域和海洋污染物。最近，在 2008 年 1 月全球禁止使用三丁基锡 (TBT) 后，Irgarol 1051 是一种光系统 II 除草剂，被用作铜基防污涂料中的“助推剂”。 Irgarol 被认为对珊瑚构成潜在风险。在这项研究中，克隆鹿角细叶从濑底岛，冲绳，日本南部收集的菌落分离，暴露于1.0$\mathrm{\mu }$g L ^-1 Irgarol 在 27.5 °C 和 30.0 °C（高于日本南部最温暖月份的温度）下持续 7 天。珊瑚颜色被转换为 RGB 值，范围从 0（最暗）到 255（最亮）。对照（无除草剂暴露）两种温度处理下的 RGB 值略有下降，但 27.5 °C 和 30.0 °C Irgarol 处理下的 RGB 值在第 3 天后增加。最大有效量子产率（$\Delta$F /${\mathit{F}}_{\mathrm{米}}$') 在 27.5 °C 和 30.0 °C 对照处理中略有增加，但在 27.5 °C 和 30.0 °C Irgarol 处理中在第 1 天后下降。暴露于 1.0 $\mathrm{\mu }$g L ^-1 Irgarol 在 RGB 值和$\Delta$F /${\mathit{F}}_{\mathrm{米}}$' 与相同温度下的对照相比。关于温差（27.5 °C vs. 30.0 °C），RGB 值和$\Delta$F /$F_{\mathrm{米}}$' 在对照和 Irgarol 处理中均检测到。我们的结果表明暴露于 Irgarol 和 30.0 °C 对A. tenuis没有显着的综合影响。这些发现表明 30.0 °C 是A. tenuis的正常可居住环境温度。A. tenuis的漂白更可能是由于暴露于 1.0$\mathrm{\mu }$g L ^-1 Irgarol 比暴露于 30.0 °C 的高海水温度。