Montefalcone Monica, Morri Carla, Bianchi Carlo Nike, Bavestrello Giorgio, Piazzi Luigi
DISTAV, University of Genoa, Corso Europa 26, 16132 Genoa, Italy.
DISTAV, University of Genoa, Corso Europa 26, 16132 Genoa, Italy.
Mar Pollut Bull. 2017 Apr 15;117(1-2):229-238. doi: 10.1016/j.marpolbul.2017.01.072. Epub 2017 Feb 6.
Marine coastal ecosystems are affected by a vast array of human-induced disturbances and stresses, which are often capable of overwhelming the effects of natural changes. Despite the conceptual and practical difficulty in differentiating between disturbance and stress, which are often used interchangeably, the two terms bear different ecological meanings. Both are external agents, but the former causes mortality or physical damage (subtraction of biomass), whereas the latter causes physiological alteration (reduction in productivity). Sensitivity of marine organisms may thus have a dual connotation, being influenced in different ways by disturbance and by stress following major environmental change. Coralligenous assemblages, which shape unique biogenic formations in the Mediterranean Sea, are considered highly sensitive to change. In this paper, we propose a method to differentiate between disturbance and stress to assess the ecological status of the coralligenous assemblages. Disturbance sensitivity level (DSL) and stress sensitivity level (SSL) of the sessile organisms thriving in the coralligenous assemblages were combined into the integrated sensitivity level of coralligenous assemblages (ISLA) index. Changes in the coralligenous status were assessed in space, along a gradient of stress (human-induced pressures) at several sites of the western Mediterranean, and in time, from a long-term series (1961-2008) at Mesco Reef (Ligurian Sea) that encompasses a mass mortality event in the 1990s. The quality of the coralligenous assemblages was lower in highly urbanised sites than that in sites in both marine protected areas and areas with low levels of urbanisation; moreover, the quality of the assemblages at Mesco Reef decreased during the last 50years. Reduction in quality was mainly due to the increase in stress-tolerant and/or opportunist species (e.g. algal turfs, hydroids and encrusting sponges), the disappearance of the most sensitive macroalgae (e.g. Udoteaceae and erect Rhodophyta) and macro-invertebrates (e.g. Savalia savaglia, Alcyonium coralloides and Smittina cervicornis), and the appearance of invasive alien algal species. Although the specific indices of SSL or DSL well illustrated the changes in the spatial or temporal datasets, respectively, their integration in the ISLA index was more effective in measuring the change experienced by the coralligenous assemblages in both space and time.
海洋沿岸生态系统受到大量人为干扰和压力的影响，这些干扰和压力往往能够压倒自然变化的影响。尽管在区分干扰和压力方面存在概念和实践上的困难（这两个术语经常互换使用），但这两个术语具有不同的生态意义。两者都是外部因素，但前者导致死亡或物理损害（生物量减少），而后者导致生理改变（生产力下降）。因此，海洋生物的敏感性可能具有双重含义，在重大环境变化后，受到干扰和压力的影响方式各不相同。在地中海形成独特生物成因构造的珊瑚藻群落被认为对变化高度敏感。在本文中，我们提出了一种区分干扰和压力的方法，以评估珊瑚藻群落的生态状况。将在珊瑚藻群落中繁衍生息的固着生物的干扰敏感度水平（DSL）和压力敏感度水平（SSL）合并为珊瑚藻群落综合敏感度水平（ISLA）指数。沿着地中海西部几个地点的压力梯度（人为压力），在空间上评估了珊瑚藻状况的变化；从梅斯科礁（利古里亚海）的长期序列（1961 - 2008年）在时间上评估了珊瑚藻状况的变化，该序列涵盖了20世纪90年代的一次大规模死亡事件。高度城市化地区的珊瑚藻群落质量低于海洋保护区和低城市化地区的珊瑚藻群落质量；此外，在过去50年里，梅斯科礁的珊瑚藻群落质量下降。质量下降主要是由于耐压力和/或机会主义物种（如藻席、水螅虫和 encrusting海绵）的增加，最敏感的大型藻类（如仙掌藻科和直立红藻）和大型无脊椎动物（如萨瓦利亚珊瑚虫、笙珊瑚和角状斯米特苔藓虫）的消失，以及外来入侵藻类物种的出现。尽管SSL或DSL的具体指数分别很好地说明了空间或时间数据集中的变化，但将它们整合到ISLA指数中在衡量珊瑚藻群落在空间和时间上经历的变化方面更有效。
