一项研究提示，全球珊瑚礁迅速而显著的衰退可能部分是由于在海藻中的化学物质导致的。
此前的研究发现了海藻增加与珊瑚减少之间的关系，但是造成这种衰退的机制尚不清楚。
在最近一项实地研究中，Douglas B. Rasher及其同事让几种海藻与珊瑚直接接触，结果发现海藻抑制了珊瑚的光合作用并且导致珊瑚白化——这是不健康的珊瑚的两个指标。这些效应局限于直接接触的区域。
实验发现人工模拟的阴影和损伤都不会影响珊瑚表面的吸水性，而给珊瑚施用海藻的脂溶性提取物引起了非常类似于直接接触海藻的损伤。
实验结果表明某些海藻含有珊瑚接触可能中毒的化学物质，这些结果或有助于解释目前许多海藻丰富的珊瑚礁内珊瑚缺乏的现象。
相关英文论文摘要：
Macroalgal terpenes function as allelopathic agents against reef corals
During recent decades, many tropical reefs have transitioned from coral to macroalgal dominance. These community shifts increase the frequency of algal–coral interactions and may suppress coral recovery following both anthropogenic and natural disturbance. However, the extent to which macroalgae damage corals directly, the mechanisms involved, and the species specificity of algal–coral interactions remain uncertain. Here, we conducted field experiments demonstrating that numerous macroalgae directly damage corals by transfer of hydrophobic allelochemicals present on algal surfaces. These hydrophobic compounds caused bleaching, decreased photosynthesis, and occasionally death of corals in 79% of the 24 interactions assayed (three corals and eight algae). Coral damage generally was limited to sites of algal contact, but algae were unaffected by contact with corals. Artificial mimics for shading and abrasion produced no impact on corals, and effects of hydrophobic surface extracts from macroalgae paralleled effects of whole algae; both findings suggest that local effects are generated by allelochemical rather than physical mechanisms. Rankings of macroalgae from most to least allelopathic were similar across the three coral genera tested. However, corals varied markedly in susceptibility to allelopathic algae, with globally declining corals such as Acropora more strongly affected. Bioassay-guided fractionation of extracts from two allelopathic algae led to identification of two loliolide derivatives from the red alga Galaxaura filamentosa and two acetylated diterpenes from the green alga Chlorodesmis fastigiata as potent allelochemicals. Our results highlight a newly demonstrated but potentially widespread competitive mechanism to help explain the lack of coral recovery on many present-day reefs.
英文论文链接：https://www.biodiscover.com/news/evolutionary/library/1551.html
