Database of sea fans spatial distribution in the northwestern Mediterranean sea

Sea fans (order : Alcyonacea) are the most remarkable and easily identifiable species of the subtidal hard substrate communities (Gili and Ros, 1985). From an ecological point of view, sea fans play an essential role (Gili and Coma, 1998) by increasing the biomass and the diversity of hard substrates (Mitchell et al, 1992; Ballesteros, 2006) via an umbrella species role providing habitat for small epifauna and a refuge for many fish (Ross and Quatrini, 2007). When their density is high enough, they form animal forests (sensu Rossi et al 2017) and become engineering species by modifying the level of turbulence and therefore of sedimentation of propagules in the benthic boundary layer (Chamberlain and Graus, 1975). In the shallow rocky habitats of the Mediterranean, five species of sea fans dominate: the white gorgonian Eunicella singularis (Esper, 1791), the orange gorgonian Leptogorgia sarmentosa (Esper, 1789), the yellow gorgonian Eunicella cavolinii (Koch, 1887), the red gorgonian Paramuricea clavata (Risso, 1826), and the red coral Corallium rubrum (Linnaeus, 1758). Some of these species, characterized by long life span, have been included in the management plans of the Gulf of Lion Marine Protected Areas, with surveys for the monitoring of the demographic structure of E. Singularis (Réserve Naturelle Marine de Cerbère-Banyuls, Aire Marine Protégée Agathoise) and C. rubrum (Réserve Naturelle Marine de Cerbère-Banyuls, Parc Marin de la Côte Bleue). In parallel with these management-related surveys, some scientific studies on the demographic structure and ecology of P. clavata, E. singularis and C. rubrum, with the aim of documenting mass mortality events (Cerrano et al. al., 2000, Garrabou et al., 2001) have been undertaken in the Parc Marin de la Côte Bleue, in the Parc National de Port-Cros, along the Côte Vermeille and Cap de Creus coast and in the Cinque Terre National Park (Garrabou and Harmelin, 2002, Torrents et al., 2005 ; Linares et al. 2008 Linares et al., 2010 ; Santangelo et al., 2011; Gori et al., 2011a ; Gori et al. 2011b; Rossi et al., 2008). The present database gathers two extensive inventory of sea fans populations performed between 2013 and 2015 in the Gulf of Lion and between 2018 and 2019 in the Ligurian Sea.
The same protocol was applied to estimate the population density of the five species in 585 stations. The 585 stations were defined a priori on a regular mesh mapping the main hard-bottom substrate units of the Gulf of Lion (Côte Bleue, Plateau des Aresquiers, Plateau du Cap d'Agde, Cap Leucate, Côte Vermeille), and surrounding the ports of Toulon, La Spezia and Bastia (Figure 1). The spacing between stations was varied from 100m to 800 m according to bathymetry steepness. Each station was geo-referenced from the surface and located on the sea bed with a mooring. Counts of individuals of the five species were made by scuba divers trained to species identification in four quadrats (1m x 1m), positionned at 5 m from the mooring along the sea bed, in the four cardinal directions. In total, the sampling required 1500 dives.
References
Ballesteros E. 2006. Mediterranean coralligenous assemblages: a synthesis of present knowledge Oceanography and Marine Biology: An Annual Review 44, 123-195
Carpine C, Grasshoff M. 1975. Les gorgonaires de la Mediterranee. Bull Inst Oceanogr Monaco 71:1–140
Cerrano, C., Bavestrello G., Bianchi C.N., Cattaneo R. Vietti, S. Bava, C. Morganti, C. Morri, P. Picco, G. Sara S. Schiaparelli S. Siccardi A. & Sponga, F. 2000. A catastrophic mass-mortality episode of gorgonians and other organisms in the Ligurian Sea (Northwestern Mediterranean), summer 1999. Ecology Letters 3: 284–293.
Chamberlain J.J. A., Graus, R.R. 1975. Water Flow and Hydromechanical Adaptations of Branched Reef Corals. : Bulletin of Marine Science 25 (1): 112-125
Garrabou J., Perez T., Sartoretto S., Harmelin J.G., 2001. Mass mortality event in red coral Corallium rubrum populations in the Provence region (France, NW Mediterranean). Mar Ecol Prog Ser 217:263–272
Garrabou J., Harmelin G. 2002. A 20-year study on life-history traits of a harvested long-lived temperate coral in the NW Mediterranean: insights into conservation and management needs. J Anim Ecol 71:966–978
Gili, J.M., & Ros, J. 1985. Study and cartography of the benthic communities of the Medes Islands (NE Spain). Marine Ecology 6, 219–238.
Gili J.M. and Coma R. 1998. Benthic suspension feeders: their paramount role in littoral marine substrates. TREE 13 (8): 316-321
Gori, A., Rossi, S., Linares, C., Berganzo, E., Orejas, C., Dale, M. & Gili, J.M. 2011a. Size and spatial structure in deep versus shallow populations of the Mediterranean gorgonian Eunicella singularis (Cap de Creus, Northwestern Mediterranean Sea)” Marine Biology, DOI: 10.1007/s00227-011-1686-7
Gori A., Rossi S., Berganzo E., Pretus J.L., Dale M.R.T., Gili J.M. 2011b. Spatial distribution patterns of the gorgonians Eunicella singularis, Paramuricea clavata and Leptogorgia sarmentosa (Cape of Creus, Northwestern Mediterranean Sea). Mar Biol 158:143-158
Linares C, Coma R, Garrabou J, Diaz D, Zabala M. 2008. Size distribution, density and disturbance in two Mediterranean gorgonians: Paramuricea clavata and Eunicella singularis. J Appl Ecol 45:688–699
Linares C., Bianchimani O., Torrents O., Marschal C., Drap P., Garrabou J., 2010. Marine Protected Areas and the conservation of long-lived marine invertebrates : the Mediterranean red coral. Marine Ecology Progress Series 402: 69-79.
Mitchell, N. D., Dardeau, M. R., Schroeder,W. W., Benke, A. C. 1992. Secondary production of gorgonian corals in the northern Gulf of Mexico. Mar Ecol. Prog. Ser. 87: 275-281
Ross S., Quattrini A. 2007. The fish fauna associated with deep coral banks off the southeastern United States. Deep Sea Research I (54): 975-1007.
Rossi S, Bramanti L, Gori A, Orejas C. 2017. An Overview of the Animal Forests of the World. In book: Marine Animal Forests, pp.1-26. SPRINGER.[DOI: 10.1007/978-3-319-17001-5_1-1]
Santangelo G., Bramanti L., Rossi S., Tsounis G., Vielmini I., Lott C., Gili J.M. 2011. Spatial patterns of variation in recruitment and post-recruitment processes of the Mediterranean precious gorgonian coral Corallium rubrum. Journal of Experimental Marine Biology and Ecology. DOI: 10.1016/j.jembe.2011.10.030
Torrents O., Garrabou J., Marshal C., Harmelin J.G., 2005. Age and size at first reproduction in the commercially exploited red coral Corallium rubrum (L.) in the Marseilles area (France, NW Mediterranean). Biol Conserv 121: 391–397
Rossi S., Tsounis G., Orejas C., Padrón T., Gili J.M., Bramanti L., Teixidó N. and Gutt J. 2008. Survey of deep-dwelling red coral (Corallium rubrum ) populations at Cap de Creus (NW Mediterranean). Marine Biology 154 (3): 533-545.

海扇（Sea fans，软珊瑚目：Alcyonacea）是潮下带硬基质群落中最显著且最易识别的物种（Gili和Ros，1985）。从生态学视角来看,海扇扮演着关键角色（Gili和Coma，1998）：它们通过伞护种（umbrella species）的作用，为小型底上生物（epifauna）提供栖息地，并为多种鱼类提供庇护所，从而增加硬基质的生物量与多样性（Mitchell等，1992；Ballesteros，2006；Ross和Quatrini，2007）。当密度足够高时，它们会形成动物森林（animal forests，sensu Rossi等，2017），并通过改变湍流程度及底栖边界层中繁殖体的沉降量，成为工程物种（engineering species）（Chamberlain和Graus，1975）。
在地中海浅海岩质生境中，五种海扇占主导地位：白色柳珊瑚（gorgonian）Eunicella singularis（Esper，1791）、橙色柳珊瑚Leptogorgia sarmentosa（Esper，1789）、黄色柳珊瑚Eunicella cavolinii（Koch，1887）、红色柳珊瑚Paramuricea clavata（Risso，1826）以及红珊瑚Corallium rubrum（Linnaeus，1758）。其中部分物种因寿命长而被纳入利翁湾海洋保护区的管理计划，包括对E. singularis（塞伯尔-班于尔斯海洋自然保护区、阿加托瓦海洋保护区）和C. rubrum（塞伯尔-班于尔斯海洋自然保护区、蓝岸海洋公园）的种群结构监测调查。与这些管理相关调查并行的是，针对P. clavata、E. singularis和C. rubrum的种群结构及生态学研究已在蓝岸海洋公园、波特克罗斯国家公园、Vermeille海岸、克鲁斯角沿岸及五渔村国家公园开展，旨在记录大规模死亡事件（mass mortality events）（Cerrano等，2000；Garrabou等，2001；Garrabou和Harmelin，2002；Torrents等，2005；Linares等，2008；Linares等，2010；Santangelo等，2011；Gori等，2011a；Gori等，2011b；Rossi等，2008）。本数据库汇集了两项海扇种群的广泛调查数据：一项于2013-2015年在利翁湾开展，另一项于2018-2019年在利古里亚海开展。
采用相同方法估算585个站点中这五个物种的种群密度。这585个站点是基于规则网格先验定义的，覆盖利翁湾的主要硬底基质单元（蓝岸、阿雷斯基耶尔高原、阿格德角高原、勒卡特角、Vermeille海岸），并围绕土伦、拉斯佩齐亚和巴斯蒂亚港口分布（图1）。站点间距根据地形坡度在100米至800米之间调整。每个站点从水面进行地理参考，并通过系泊装置定位到海床。由经过物种识别训练的水肺潜水员在四个样方（1m×1m）中计数这五个物种的个体数量，样方位于海床上距系泊装置5米处，沿四个基本方向分布。采样共需1500次潜水。
参考文献
Ballesteros E. 2006. 地中海珊瑚礁组合：现有知识综述. Oceanography and Marine Biology: An Annual Review 44, 123-195
Carpine C, Grasshoff M. 1975. 地中海的柳珊瑚. Bull Inst Oceanogr Monaco 71:1–140
Cerrano C, Bavestrello G, Bianchi CN, Cattaneo R Vietti, S Bava, C Morganti, C Morri, P Picco, G Sara S Schiaparelli S Siccardi A & Sponga F. 2000. 1999年夏季利古里亚海（西北地中海）柳珊瑚及其他生物的灾难性大规模死亡事件. Ecology Letters 3:284–293
Chamberlain JJA, Graus RR.1975. 分支造礁珊瑚的水流与流体力学适应. Bulletin of Marine Science 25(1):112-125
Garrabou J, Perez T, Sartoretto S, Harmelin JG.2001. 普罗旺斯地区（法国，西北地中海）红珊瑚Corallium rubrum种群的大规模死亡事件. Mar Ecol Prog Ser 217:263–272
Garrabou J, Harmelin G.2002. 西北地中海一种受捕捞的长寿温带珊瑚生活史特征的20年研究：对保护与管理需求的启示. J Anim Ecol 71:966–978
Gili JM, Ros J.1985. 梅德斯群岛（西班牙东北部）底栖群落的研究与制图. Marine Ecology 6:219–238
Gili JM, Coma R.1998. 底栖滤食者：它们在滨海基质中的关键作用. TREE 13(8):316-321
Gori A, Rossi S, Linares C, Berganzo E, Orejas C, Dale M & Gili JM.2011a. 地中海柳珊瑚Eunicella singularis（克鲁斯角，西北地中海）深海与浅海种群的大小及空间结构. Marine Biology, DOI:10.1007/s00227-011-1686-7
Gori A, Rossi S, Berganzo E, Pretus JL, Dale MRT, Gili JM.2011b. 柳珊瑚Eunicella singularis、Paramuricea clavata和Leptogorgia sarmentosa（克鲁斯角，西北地中海）的空间分布模式. Mar Biol 158:143-158
Linares C, Coma R, Garrabou J, Diaz D, Zabala M.2008. 两种地中海柳珊瑚（Paramuricea clavata和Eunicella singularis）的大小分布、密度及干扰. J Appl Ecol 45:688–699
Linares C, Bianchimani O, Torrents O, Marschal C, Drap P, Garrabou J.2010. 海洋保护区与长寿海洋无脊椎动物的保护：地中海红珊瑚. Marine Ecology Progress Series 402:69-79
Mitchell ND, Dardeau MR, Schroeder WW, Benke AC.1992. 墨西哥湾北部柳珊瑚的次级生产力. Mar Ecol Prog Ser 87:275-281
Ross S, Quattrini A.2007. 美国东南部外海深珊瑚礁相关的鱼类区系. Deep Sea Research I(54):975-1007
Rossi S, Bramanti L, Gori A, Orejas C.2017. 世界动物森林概述. 载于《Marine Animal Forests》, pp.1-26. SPRINGER.[DOI:10.1007/978-3-319-17001-5_1-1]
Santangelo G, Bramanti L, Rossi S, Tsounis G, Vielmini I, Lott C, Gili JM.2011. 地中海珍贵柳珊瑚Corallium rubrum的补充（recruitment）及补充后过程的空间变异模式. Journal of Experimental Marine Biology and Ecology. DOI:10.1016/j.jembe.2011.10.030
Torrents O, Garrabou J, Marshal C, Harmelin JG.2005. 马赛地区（法国，西北地中海）商业捕捞红珊瑚Corallium rubrum（L.）的首次繁殖年龄与大小. Biol Conserv 121:391–397
Rossi S, Tsounis G, Orejas C, Padrón T, Gili JM, Bramanti L, Teixidó N & Gutt J.2008. 克鲁斯角（西北地中海）深海红珊瑚（Corallium rubrum）种群调查. Marine Biology 154(3):533-545