Jones Ross
Centre for Marine Studies, Seddon Building (No 82C), St. Lucia Campus, The University of Queensland, Brisbane, QLD 4072, Australia.
Mar Pollut Bull. 2005;51(5-7):495-506. doi: 10.1016/j.marpolbul.2005.06.027. Epub 2005 Jul 27.
The recent discovery of contamination of the tropical marine environment by Photosystem II (PSII) herbicides used in agriculture and antifouling paints has led to concerns regarding the effects on corals and their symbiotic dinoflagellate algae. In reviewing the ecotoxicological studies conducted so far, PSII herbicides appear able to readily penetrate the coral tissues and rapidly (within minutes) reduce the photochemical efficiency of the intracellular algal symbionts. The dinoflagellates appear at least as sensitive to PSII herbicides as other phototrophs tested so far, with photosynthesis being affected at exceptionally low concentrations (i.e. in the ngl(-1) range). At these levels and over short exposure periods, the effects can be fully reversible (i.e. when corals are returned to clean seawater) and vary according to type of herbicide; however, when exposed to higher concentrations in the light or over longer exposure periods, it results in a long-term sustained reduction of the photochemical efficiency of the algae (symptomatic of chronic photoinhibition). This can result in the dissociation of the symbiosis (bleaching) which is a common but nevertheless significant sub lethal stress response requiring many months to recover from. It is argued that the reliance of corals on an endosymbiotic photoautotrophic energy source, together with predilection for the symbiosis to dissociate when photosynthesis of the algae is affected, renders coral particularly susceptible to changes in environmental conditions-and especially phytotoxins such as PSII herbicides.
近期发现，农业和防污涂料中使用的光系统II（PSII）除草剂已污染热带海洋环境，这引发了人们对其对珊瑚及其共生双鞭毛藻影响的担忧。在回顾迄今为止进行的生态毒理学研究时，PSII除草剂似乎能够轻易穿透珊瑚组织，并迅速（在数分钟内）降低细胞内藻类共生体的光化学效率。双鞭毛藻对PSII除草剂的敏感性至少与迄今为止测试的其他光合生物一样高，在极低浓度（即纳克/升范围内）下光合作用就会受到影响。在这些浓度水平和短暴露时间内，影响可能是完全可逆的（即当珊瑚回到清洁海水中时），并且因除草剂类型而异；然而，当在光照下暴露于更高浓度或更长暴露时间时，会导致藻类光化学效率长期持续降低（慢性光抑制的症状）。这可能导致共生关系的解离（白化），这是一种常见但仍然严重的亚致死应激反应，需要数月时间才能恢复。有人认为，珊瑚依赖内共生光合自养能量来源，以及在藻类光合作用受到影响时共生关系易于解离的特性，使得珊瑚特别容易受到环境条件变化的影响——尤其是像PSII除草剂这样的植物毒素。
