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Abstract：
Contaminants may affect ecosystem functioning by reducing the fitness of organisms and these impacts may cascade through ecosystems, particularly if the sensitive organisms are also habitat-forming species. Understanding how sub-lethal effects of toxicants can affect the quality and functions of biogenic habitats is critical if we are to establish effective guidelines for protecting ecosystems. We carried out a global systematic review and meta-analysis critically evaluating contaminant effects on properties of habitat-formers linked to ecosystem functioning. We reviewed a total of 95 publications. However, 40% of publications initially captured by the literature search were identified as having flaws in experimental design and ~11% did not present results in an appropriate way and thus were excluded from the quantitative meta-analysis. We quantitatively reviewed 410 studies from 46 publications, of which 313 (~76%) were on plants and seaweeds, that is macro-algae, saltmarsh plants and seagrasses, 58 (~14%) studied corals and 39 (~10%) looked at toxicant impacts on bivalves, with 70% of those on mussels and the remaining studies on oysters. Response variables analysed were photosynthetic efficiency, amount of chlorophyll a (as a proxy for primary production) and growth of plants, seaweeds and corals as well as leaf area of plants. We also analysed filtration, growth and respiration rates of bivalves. Our meta-analysis found that chemical contaminants have a significant negative impact on most of the analysed functional variables, with the exception of the amount of chlorophyll a. Metals were the most widely harmful type of contaminant, significantly decreasing photosynthetic efficiency of kelps, leaf area of saltmarsh plants, growth of fucoids, corals and saltmarsh plants and the filtration rates of bivalves. Organic contaminants decreased the photosynthetic efficiency of seagrass, but had no significant effects on bivalve filtration. We did not find significant effects of polycyclic aromatic hydrocarbons on any of the analysed functional variables or habitat-forming taxa, but this could be due to the low number of studies available. A meta-regression revealed that relationships between concentrations of metal contaminants and the magnitude of functional responses varied with the type of metal and habitat-former. Increasing concentrations of contaminants significantly increased the negative effects on the photosynthetic efficiency of habitat-formers. There was, however, no apparent relationship between ecologically relevant concentrations of metals and effect sizes of photosynthetic efficiency of corals and seaweeds. A qualitative analysis of all relevant studies found slightly different patterns when compared to our quantitative analysis, emphasising the need for studies to meet critical inclusion criteria for meta-analyses. Our study highlights links between effects of contaminants at lower levels of organisation (i.e. at the biochemical and/or physiological level of individuals) and ecological, large-scale impacts, through effects on habitat-forming species. Contaminants can clearly reduce the functioning of many habitat-forming marine species. We therefore recommend the adoption of routine measures of functional endpoints in monitoring and conservation programs to complement structural measures.
摘要：
污染物可能会通过降低生物体的适应性来影响生态系统功能，这些影响可能会通过生态系统级联，特别是如果敏感生物也是形成栖息地的物种。如果我们要建立保护生态系统的有效准则，了解有毒物质的亚致死效应如何影响生物栖息地的质量和功能至关重要。我们进行了全球系统评价和荟萃分析，批判性地评估了污染物对与生态系统功能相关的栖息地形成者特性的影响。我们共审查了95份出版物。然而,最初通过文献检索获得的出版物中有40％被确定为在实验设计中存在缺陷，约11％没有以适当的方式呈现结果，因此被排除在定量荟萃分析之外。我们定量回顾了来自46种出版物的410项研究，其中313(~76%)在植物和海藻上，那是宏观藻类，盐沼植物和海草，58(~14%)研究了珊瑚，39(~10%)研究了毒物对双壳类动物的影响，其中70%在贻贝上，其余的研究在牡蛎上。分析的响应变量是光合效率，叶绿素a的量(作为初级生产的代表)和植物的生长，海藻和珊瑚以及植物的叶面积。我们还分析了过滤，双壳类动物的生长和呼吸速率。我们的荟萃分析发现，化学污染物对大多数分析的功能变量有显著的负面影响，除了叶绿素a的数量。金属是最广泛有害的污染物类型，显著降低海带的光合效率，盐沼植物的叶面积，岩藻的生长，珊瑚和盐沼植物和双壳类动物的过滤速率。有机污染物降低了海草的光合效率，但对双壳类动物的过滤没有显著影响。我们没有发现多环芳烃对任何分析的功能变量或栖息地形成分类单元的显着影响，但这可能是由于现有研究数量较少。元回归表明，金属污染物的浓度与功能响应的大小之间的关系随金属类型和栖息地形成者而变化。污染物浓度的增加显着增加了对生境形成者光合效率的负面影响。有,然而,生态相关的金属浓度与珊瑚和海藻光合效率的影响大小之间没有明显的关系。对所有相关研究的定性分析发现，与我们的定量分析相比，模式略有不同，强调研究需要满足荟萃分析的关键纳入标准。我们的研究强调了污染物在较低组织水平（即在个体的生化和/或生理水平）和生态，大规模影响，通过对形成栖息地的物种的影响。污染物可以明显减少许多形成栖息地的海洋物种的功能。因此，我们建议在监测和保护计划中采用功能终点的常规措施，以补充结构措施。
