Bleaching in foraminifera with algal symbionts: implications for reef monitoring and risk asessment
Bleaching in foraminifera with algal symbionts: implications for reef monitoring and risk asessment
复制标题
有孔虫与藻类共生体的漂白：对珊瑚礁监测和风险评估的影响
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
S. Toler
中科院分区：
文献类型：
--
作者：
P. Hallock;Dana E Williams;E. Fisher;S. Toler
栖息在珊瑚礁中的较大有孔虫与造礁珊瑚具有共同的关键特征：它们是碳酸钙的多产者，它们在生理上依赖于藻类内共生体，并且近几十年来这两个群体的代表都遭受了白化事件。自1991年以来，所有亚热带海洋的Amphistegina种群都观察到了白化现象，白化高峰出现在1992年，次高峰出现在1998年和2005年。表现出慢性、中等强度白化的Amphistegina种群的特征是，贝壳破损、贝壳畸形、捕食证据和微生物侵染的发生率异常高。无性繁殖受到严重影响；部分漂白的父母所产下的幼崽通常数量较少，其中许多的形状和大小都异常。珊瑚和 Amphistegina 之间的主要区别在于，珊瑚通常通过排出共生体来漂白，而 Amphistegina 在损坏的共生体被消化时进行漂白，并且大规模珊瑚白化需要强光，但与高温最相关，而 Amphistegina 的白化是由光引起的。双栖鱼对太阳辐射的较短波长（300-490 nm）特别敏感，由于平流层臭氧消耗，过去 30 年来，在清澈的珊瑚礁水域中，太阳辐射的强度相对于较长可见波长（> 490-700 nm）有所增加。 Amphistegina 种群的丰度和视觉评估可用作低成本风险评估工具。这些原生生物对数天至数周的环境条件敏感，并提供了一种快速区分水质（局部）和光氧化（全局）应激的方法。基于现场测量和低成本指标相结合的风险评估可以为资源管理者提供必要的信息，以决定何时需要更昂贵的化学或分子程序来确定当地的压力源。
Reef-dwelling larger foraminifers share key characteristics with reefbuilding corals: they are prolific producers of calcium carbonate, they are physiologically dependent upon algal endosymbionts, and representatives of both groups have suffered bleaching episodes in recent decades. Since 1991, bleaching has been observed in populations of Amphistegina in all subtropical oceans, with peak bleaching in 1992 and secondary peaks in 1998 and 2005. Amphistegina populations exhibiting chronic, intermediate-intensity bleaching characteristically show anomalously high incidences of shell breakage, shell deformities, evidence of predation, and microbial infestation. Asexual reproduction is profoundly affected; broods from partly bleached parents typically have fewer individuals, many of which are anomalous in shape and size. Key differences between bleaching in corals and Amphistegina are that corals typically bleach by expelling their symbionts, while Amphistegina bleach when damaged symbionts are digested, and that mass coral bleaching requires high light but correlates most consistently with elevated temperatures, while bleaching in Amphistegina is induced by light. Amphistegina are particularly sensitive to the shorter (300-490 nm) wavelengths of solar radiation, which have increased in intensity relative to longer visible wavelengths (>;490-700 nm) in clear reef waters over the past 30 years as a consequence of stratospheric ozone depletion. Abundances and visual assessments of Amphistegina populations can be used as a low-cost risk-assessment tool. These protists are sensitive to environmental conditions over days to weeks, and provide a method to quickly distinguish between water quality (local) and photo-oxidative (global) stresses. Risk assessments based on the combined use of in situ measurements and low-cost indicators can provide resource managers with essential information to decide when more costly chemical or molecular procedures are needed to determine local sources of stress.