Testing the 'photoinhibition' model of coral bleaching using chemical inhibitors
Testing the 'photoinhibition' model of coral bleaching using chemical inhibitors
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DOI：
10.3354/meps284133
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发表时间：
2004-01-01
影响因子：
2.5
通讯作者：
Jones, RJ
中科院分区：
文献类型：
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作者：
Jones, RJ
将硬珊瑚Seriatopora hystrix的外植体暴露于亚致死浓度的除草剂敌草隆DCMU（N '-（3，4-二氯苯基，-N，N-二甲基脲））和重金属铜。脉冲幅度调制（PAM）叶绿素荧光技术被用来评估对光合效率的藻类共生体在组织中（在Symbio），叶绿素荧光和共生藻类计数（归一化表面积）的影响被用来评估珊瑚漂白的程度。在30 μ g DCMU 1（-1）时，共生体中藻类共生体的最大有效量子产率（Δ F/F-m ′）和最大潜在量子产率（F-v/F-m）均降低。珊瑚随后失去了它们的藻类共生体并变色（漂白），特别是在它们暴露在阳光下的上部表面。在相同的DCMU浓度下，但在弱光（5%的生长辐照度）下，Δ F/F-m'显著降低，但F-v/F-m仅轻微降低，藻类略有损失。藻共生体的损失也注意到后7天暴露于浓度低至10 μ g DCMU l（-1）在正常生长的辐照度下，和后14天暴露于10 μ g DCMU l（-1）在减少的辐照度。总的来说，结果表明，DCMU诱导的漂白是由藻类共生体的光依赖性光失活引起的，并且当F-v/F-n（日落后2小时测量）降低到小于或等于0.6的值时发生漂白。高浓度的铜（60 μ g Cu l（-1）处理10 h）也能诱导S. hystrix，但不影响共生体中藻类的量子产率。用分离的藻类进行的试验表明，需要显著更高的浓度（300 μ g Cu l（-1），8小时）来显著降低量子产率。因此，铜诱导的漂白发生不影响藻类光合作用，可能与对宿主（动物）的影响。有人认为，温水漂白的珊瑚类似于这两种类型的化学诱导漂白，这表明需要一个综合的珊瑚漂白模型，涉及温度对宿主（珊瑚）和藻类共生体的影响。
Explants of the hard coral Seriatopora hystrix were exposed to sublethal concentrations of the herbicide diuron DCMU (N'-(3,4-dichlorophenyl,-N,N-dimethylurea)) and the heavy metal copper. Pulse amplitude modulated (PAM) chlorophyll fluorescence techniques were used to assess the effects on the photosynthetic efficiency of the algal symbionts in the tissue (in Symbio), and chlorophyll fluorescence and counts of symbiotic algae (normalised to surface area) were used to assess the extent of coral bleaching. At 30 mug DCMU l(-1), there was a reduction in both the maximum effective quantum yield (DeltaF/F-m') and maximum potential quantum yield (F-v/F-m) of the algal symbionts in symbio. Corals subsequently lost their algal symbionts and discoloured (bleached), especially on their upper sunlight-exposed surfaces. At the same DCMU concentration but under low light (5% of growth irradiance), there was a marked reduction in DeltaF/F-m' but only a slight reduction in F-v/F-m and slight loss of algae. Loss of algal symbionts was also noted after a 7 d exposure to concentrations as low as 10 mug DCMU l(-1) under normal growth irradiance, and after 14 d exposure to 10 mug DCMU l(-1) under reduced irradiance. Collectively the results indicate that DCMU-induced bleaching is caused by a light-dependent photoinactivation of algal symbionts, and that bleaching occurs when F-v/F-n, (measured 2 h after sunset) is reduced to a value of less than or equal to 0.6. Elevated copper concentrations (60 mug Cu l(-1) for 10 h) also induced a rapid bleaching in S. hystrix but without affecting the quantum yield of the algae in symbio. Tests with isolated algae indicated that substantially higher concentrations (300 mug Cu l(-1) for 8 h) were needed to significantly reduce the quantum yield. Thus, copper-induced bleaching occurs without affecting the algal photosynthesis and may be related to effects on the host (animal). It is argued that warm-water bleaching of corals resembles both types of chemically induced bleaching, suggesting the need for an integrated model of coral bleaching involving the effect of temperature on both host (coral) and algal symbionts.