岩石海岸的生物多样性:分区和生态关系

  由于受到潮汐的影响,在大西洋基岩海岸上很容易观察到定居的生物。各种地衣或大型褐藻根据水位和生活条件占主导地位并形成水平带。一些固着或活动能力稍弱的动物也以不太明显的水平带状分布。其他动物和藻类则更不规则地分布在盆地、海峡和岩石悬垂处。具体的多样性在裸露区域会随高度下降,并且当条件变得太恶劣时也会呈现这样的规律,如海浪太剧烈、光照太强或盐度变化很大时。因此,基岩海岸上的生物对暴露于空气中或海浪的扰动有许多生物学适应性,有许多与营养相关的特性和相互关系。

  大西洋沿岸由于受潮汐现象的影响,部分海岸线会根据坡度和潮汐范围暴露于一个可变的区域内。因此,生活在这个潮汐平衡区和周边地区的生物必须长时间承受一个非常特殊和非常多变的环境。根据矿物基质的特性,海岸线上的外观差异显著并且有不同的相应的生态系统。

  因此,在本文主要讨论的基岩海岸上,藻类,尤其是褐藻(详情参见焦点藻类及其分类)和固定在岩石上的地衣通常占主导地位,并且分布在从陆地环境到海洋环境的水平带上;这正是我们坚持认为这些结构性物种很容易观察的原因。一些固着或活动能力弱的动物也有这样的垂直分区,而活动能力强的物种(鱼、虾、各种软体动物)则随着海水的运动而移动,或在盆地或有遮蔽的区域中生存。

  在泥沙滩的海岸上,动物的带状分布不那么明显,这是由于它们主要埋栖在泥沙中生活,特别是在退潮时。除了当地的开花有根植物外,植物数量较少:米草属、海蓬子属或其他开花植物处于平静的较高的海岸,而大叶藻则在非常低的海岸。由于缺乏稳定的附着基,这里几乎没有藻类;这些环境中的动物与岩石中的动物有很大的不同。这些生态系统的组织和功能与基岩海岸的生态系统非常不同,因此需要用一篇完整的文章来阐述这些生态系统。

环境百科全书-生命-海岸
图 1. 大叶藻Zostera marina海草场。大叶藻是一种海洋开花鳗草植物,位于沙质低潮区。 由于其栖息地和形态(尤其是长带状叶子的存在),许多人认为鳗草是一种藻类。事实上,它的根扎在沙子里。鳗草海草场具有很高的生物多样性。

1. 生态因素及其影响

  许多生态因子以及由此产生的物理化学梯度直接影响海岸线上生物的分布,而这些因子往往相互关联,因此解释起来有时会变得复杂。

1.1 空气暴露和脱水的持续时间

  这个因素对大西洋和英吉利海峡的潮汐海岸至关重要(在地中海非常次要)(见潮汐)。潮间带会在大约 24 小时内出现两次交替高潮淹没和低潮露出的现象(图 2)。这对动植物尤其是海洋生物造成了严重的限制。此外,由于月球和季节周期的影响,潮汐的幅度变化很大:满月或新月和春分或秋分点对潮汐影响很大,但是在每月的上弦月和下弦月以及冬至夏至时,潮汐波动幅度很低[1](见光周期和生物体)。

环境百科全书-生命-海岸
图 2. 布列塔尼的岩石海岸,处于低潮 (A) 和 6 小时后的高潮 (B)。

  因此,生活在海岸线最高处的生物至少在 80% 的时间里会脱离海洋环境而暴露于空气中。在离开海洋环境期间,它们会直接暴露在阳光直射、温度变化以及与新鲜雨水或干燥相关的渗透压力下。此外,在空气中,海洋野生动物无法再从水中吸收溶解氧;这意味着动物可以在周围保留一些水,或者,更罕见的是,它们改变自己的呼吸方式[1]。这些条件越稳定,对滨海底栖物种的限制就越少;它们通常与永久淹没区域中的物种相同[1]

  潮差,即最低高海平面和最高海平面之间的最大水位差,是特定区域的典型特征,由海岸的构造决定:圣米歇尔山海湾的潮差为14m,罗斯科夫的潮差为8.50m,勒阿弗尔和南特的潮差约6m,而比亚里茨的潮差仅超过4m。潮差越大,潮汐摆动区域越广,越多样化,潮间带就越宽,因此,瑟堡到布列斯特段法国西海峡海岸意义非凡。

环境百科全书-生命-海岸
图3.退潮时有不同分层的岩石前滩;这张照片中不存在潮下带

  因此,我们根据海洋影响和露出持续时间(图3和图7),定义了海岸的四个等级[1][2]

  • 与陆地生态系统直接相连并受盐雾影响的浅水位;
  • 只有在非常高的潮汐和风暴时才会被淹没的潮上带;
  • 潮间带不断被潮汐席卷,可细分为三层;
  • 潮下带层次,其上层仅在涨潮时出现,每次出现时间不到一个小时。其下层根据在海下的光照情况可延伸至海底 10 至 30 m.

  沿着岩基前滨越往下走,海藻就越大种类也越多,动物的种类也就越多;因此,渔民们会在涨潮时步行捕捉或收集龙虾、海藻、滨螺和鲍鱼。生物量和生产力也在潮下带地区最高。

1.2 海水扰动

  这一因素与海流和海浪有关,很大程度上取决于海岸的方向和构造:暴露在西部或悬崖脚下的岩石海角有强烈的扰动,而有遮蔽的海湾和河口底部扰动轻微。这对生物有较大影响。的确,某些太脆弱或太长的藻类种类,由于不能牢固固定,或因为太柔软会被强烈的海浪或动物撕碎或撕裂,从而无法在海水冲击的环境中生存。而其它的则需要氧含量高的冲击环境才能生存。值得注意的是,同一海岸在中上海岸可能会受到剧烈冲击(因为高潮涌浪到达时没有障碍物阻挡),而在中下海岸或潮下带则会相对平静(在低潮时,海浪会因各种障碍而减慢)。

环境百科全书-生命-海岸
图4.海洋搅动对潮间带生物的影响:A、剧烈扰动模式,无藻类和固着动物; B、中度扰动模式,遮蔽的边缘有锯齿墨角藻和各种红藻; C,平静模式,泡叶藻。

  根据观察到的对生物体(存在的物种、大小和生物量)的影响,可以确定三种海水扰动模式:“剧烈扰动”、“中度扰动”和“平静”(图 4)。 我们看到,潮间带被海水冲刷得越剧烈,藻类生物量就越少,甚至能变成没有任何生物的裸露岩石。

1.3 光照

环境百科全书-生命-海岸
图5.树荫下岩石的悬垂物,带有Dendrodoagrossularia或海刺,社会海鞘。

  藻类和地衣需要光来进行光合作用,但过多的光通常对一些生物是有害的,因为曾经这些生物有时是由浑浊的水层保护的。因此,在中层海岸,一些物种为了躲避阳光,躲在其他更大的藻类下面——例如潮上带的红藻丛生链球菌(Catenella cespitosa)——躲在永远潮湿的岩石底部(图4B)或悬垂的岩石下。许多绿藻能承受高强度光照(见下图17A),褐藻也能承受高强度光照。阳光直射对许多动物来说也是个问题,比如海绵和海鞘(图5),因为这会带来脱水和增温。

1.4 其他物理化学因素

  关于附着基的性质,大多数大型藻类生活在岩石或砾石上,由附着器(见下图 14B)或假根固定,一旦脱离固定物,这些藻类很快就会死亡。因此,基岩海岸是它们最喜欢的生境。表面粗糙的花岗岩、片麻岩和粗砂岩是对它们最有利的,而光滑的砂岩或泥灰岩以及白垩岩则不太有利,因为它们很容易被海水侵蚀破坏。一些小型藻类会附着在其他藻类上。许多动物只能通过固定在各种坚固的支撑物上才能生存(图5和图6以及下面的图19):包括许多腹足类动物、贻贝、藤壶、海葵、海绵、海鞘……

  洪水期间,剧烈的温度变化和冰冻对大多数只能生活在前滨底部的海洋生物是有害的。此外,比亚里茨和敦克尔克之间的动植物区系并不相同,因为有些物种喜欢淡水;例如大型褐藻。

  在河口,水的盐度较低,而且最重要的是变化更大,导致许多海洋物种消失。水也很混浊,因为里面充满了泥浆,并且许多藻类在低水位中不再有足够的光照。因此,即使生产力仍然很高,全球生物多样性也在急剧下降。

1.5 种间竞争

环境百科全书-生命-海岸
图6.A,展示了两种藤壶之间的竞争实例。虽然小藤壶Chthamalus stellatus的基础生态位覆盖了涨潮和退潮之间的整个区域,但有效的生态位受到较大的藤壶Balanus balanoides的存在的限制。[图片来源:Chthamalus 由 Michael Maggs 拍摄 (CC BY-SA 3.0) Balanus 由Auguste Le Roux 拍摄 (CC BY-SA 4.0-3.0-2.5-2.0-1.0),通过Wikimedia Commons]。B,中海岸没有藻类的海浪冲刷岩石,在这张图片的右边只有一种黑色垫子状的海洋地衣Lichina pygmaea、一种腹足类Patella vulgata、以及固定的甲壳类动物藤壶Chthamalus stellatus,数量非常丰富。(译者注:黑垫中只有一种海洋地衣,矮生地衣(Lichina pygmaea),一种腹足动物,普通帽贝(Patella vulgata),以及一种固定的甲壳类动物,星形藤壶(Chthamalus stellatus))。这些动物有一个外壳或坚固的钙质板,能够很好地抵抗海浪。

  对于位置或光线的竞争在生物的分区中起着重要作用;它们最适应当地的生态条件,有时是最先到达的物种占据主导地位,这就导致给其他物种留下的空间很小。事实证明,在特定地区存在竞争性物种会迫使另一个物种限制其在海岸上的位置。图6A显示了两种藤壶物种的情况:在有Balanus balanoides(小藤壶)的情况下,Chthamalus stellatus(大藤壶)被限制在上层,而它可以生活在较低层;这两个物种通过滤食的方式生活[3]。图6B展示了潮间带地区的另一个竞争案例:这里环境的强烈搅动使海藻难以生存,这就使得需要光照的小盾藻衣(Lichina)长出了短的软垫;藤壶的幼虫只在没有地衣的地方定居;最后,因为有许多固定的藤壶,所以就没有多少空间留给软垫附着在岩石上生长了!

2. 地衣或棕色海藻带

  结合不同阶段的海拔分区和不同的海水搅动模式,我们可以得到下表(图7),其中展示了我们基岩海岸的各种植物带[2][4]

环境百科全书-生命-海岸
图7.藻类和地衣根据海水的平均扰动情况分层。名称的颜色对应于褐藻(棕色)、红藻(红色)、蓝藻(蓝绿色)和地衣。优势种以大写字母为主,其他种类以小写字母为主。左边的百分比对应于不同级别的出现时间:0%在极高海平面,50%在潮间带,100%在极低海平面。

2.1. 潮上带的地衣

  地衣最初是陆生生物。 这就是为什么它与藻类和海洋动物不同的原因,它们的特定多样性会随着向海洋的下降而减少。许多种类的地衣都可以在海岸带岩石上找到,其中一些也生活在内陆(石黄衣Xanthoria parietina),而另一些则是典型的海洋海岸线生活型(黑地衣Verrucaria maura,Lichina spp[3]

环境百科全书-生命-海岸
图8.从潮下带到潮间带上部的地衣和藻类带

  由于颜色对比强烈,从远处可以看到地衣带(图 8)。上面的浅海层也有一些能够承受滨海盐雾的开花植物,还能看见树花属(Ramalina)的浅绿色簇,石黄衣属(Xanthoria)的橙黄色叶状体和从白色到深灰色或棕色都有的各种壳状体,在许多地衣属(图9A)中最为显眼。

环境百科全书-生命-海岸
图9.A.暴露在滨海盐雾中的地衣:树花属(Ramalina spp.)。灰绿色丛生的石黄衣属(Xanthoria spp.)。在橙色斑块中,灰色外壳的Ocrolechia Parella;B,潮上带地衣,有时被海洋覆盖;黑色的Verrucaria Maura和黄色的Caloplaca spp

  高潮时,海岸带上部被橙地衣Caloplaca marinaC. maritima的外壳所定植,它们散布在几乎连续的黑地衣(Hydropunctaria(=Verrucaria) maura)黑带中(图 9B)。这种黑色细壳地衣经常被误认为是漏油的残留物! 在中海岸带的稀有地衣中有矮生地衣(Lichina pygmaea),它们生活在非常恶劣的环境中(图6)。

  在非常粗糙的海岸,浅水和潮上带向上延伸有非常宽的地衣带(Finistère, QuiberonLa Hague(菲尼斯泰尔、基伯隆或拉黑格)悬崖上超过20米);这些海岸非常恶劣的生存条件有利于地衣生长,与开花植物相比,地衣与丝状真菌、绿藻或蓝藻的共生使自身更具抵抗力。另一方面,在有波浪遮挡的河口,所有这些带加在一起的高度只有20厘米;平静的条件甚至允许橡树朝大海生长,在高潮时浸润树枝。

2.2 中、低水位的褐藻

环境百科全书-生命-海岸
图10.潮间带上部未受太多干扰的管状紫菜(A)和螺旋藻(B)

  褐藻或褐藻纲、岩藻目和层藻目,主要通过其生物量在岩石前滨占据主导地位[2]。人们层用烤箱炙烤它们来提取苏打,或者用来肥田,其在诺曼底被称为varech,在布列塔尼被称为goëmon[15],在英语中是wrach或kelp。因此,它们形成了潮间带和潮下带的特征带。它们的大小和生物量随着它们的分布位置的下降而增加:Pelvetia为10 cm,Ascophyllum 和 Sargassum约为1m,而海条藻和海带(HimanthaliaLaminaria hyperborea)则高达5m。有些藻类的浮体使它们在高潮的时候可以垂直地站在阳光下,如水囊藻和黑角藻。

环境百科全书-生命-海岸
图11.平静的滨海中部尤为常见的节囊藻Ascophyllum nodosum及其寄生的红藻Vertebrata lanosa

  潮间带上部(约70-80%的时间暴露于空气)由两条海藻带组成,它们可以很好地承受干燥,并可以失去75%的水而不会死亡;分别是管状紫菜(Pelvetia canaliculata(图10A))和墨角藻(Fucus spiralis(图10B));但这些藻类在非常恶劣的环境中无法生存(图6)。

环境百科全书-生命-海岸
图12A.轻度冲刷或平静海岸中带有漂浮气囊的水泡藻Fucus vesiculosus;B,水泡藻变种Fucus vesiculosus var. linearis,被海水拍打严重,没有漂浮气囊

  潮间带中部(约50%的时间暴露于空气)最具代表性的是囊叶藻(Ascophyllum nodosum)和墨角藻(Fucus vesiculosus)。前者(图11)在平静的潮间带大量生长,形成厚垫,并经常被一种红藻——Vertebrata lanosa寄生。墨角藻(Fucus vesiculosus)(图12A)在恶劣的生存环境中占主导地位,但在极端恶劣的环境下无法生存,除非形成特殊的适应方式,即变得更窄、更坚硬、气囊退化(图12B)。

环境百科全书-生命-海岸
图13.位于中海岸下部的锯齿状锯齿藻(Fucus Serratus)

  最后,潮间带下部(约20%到30%的时间暴露于空气)大部分被锯齿墨角藻占据,此类藻也没有气囊(图13)。

  在平静的环境下,潮间带下部和潮下带上部的底部(不到10%的时间暴露于空气)生活着大的糖海带(Saccharina latissima(= Laminaria saccharina))(图14A),或多或少有些恶劣的环境中还生长着柄扁平且柔软的囊根裂叶藻(Saccorhiza polyschides)(图14B),二分轴很长很窄、可食用的伸长海条藻(Himanthalia elongata(图15)),也称海豆,以及具有光滑和灵活的圆柱形柄的掌状海带(图15)。

环境百科全书-生命-海岸
图14.A,宽果海藻(Saccharina latissima),有长长的波浪状叶状体,处于平静模式;B,多胞海藻Saccorhiza polyschides,由球茎复合体的附着器附着,柄扁平;棕榈藻(Palmaria palmata),位于右上角,大型红藻,位于潮间带下部的极限,被海水冲刷严重。
环境百科全书-生命-海岸
图15. 两种典型的潮下带上部植物具有狭窄的二分叶状体的细长海带Himanthalia elongata,;具有深深撕裂的叶片和柔韧的圆柱形叶柄的海带Laminaria digitata。

  最后一条带,在潮下带从未或很少暴露在空气中,由北方海带(Laminaria hyperborea)组成,具有坚硬的圆柱形柄。这些藻类的生物量有时非常高,可以形成所谓的“水下森林”。在罗斯科夫、乌桑特和勒孔奎特(Roscoff、Ouessant 和 Le Conquet)之间,该物种与其他海带形成了欧洲最大和最丰富的藻类区域(海藻海岸),人们在该区域开展藻酸盐提取等半工业化开发。

3. 其他生物的分布

3.1. 红藻和绿藻

  其他藻类不形成真正的带状、连续或规则的分布[2]

环境百科全书-生命-海岸
图16.A. 固定在低层岩石上的石莼Ulva spp.;B.潮间带下部的红藻角叉菜Chondrus crispus

  绿藻,或绿藻纲Chlorophyceae,大多是机会主义的,在几乎没有竞争的地方生长迅速;它们通常能承受强烈的阳光、盐度或温度的变化以及大量的人为产生的硝酸盐。其中,石莼Ulva spp. (图16a)也称海莴苣,夏季会在一些岩石上繁殖,然后从岩石上脱落,聚集在平静的海湾里开始腐烂,产生恶臭的腐烂绿潮(见环境中的硝酸盐)。

  另一方面,红藻,或红藻纲Rhodophyceae,不能够忍受过多的光照或海水盐度的显著降低;在冬天从暗红色几乎变成黑色,在夏天变成绿色,因为红色的色素会被紫外线破坏。因此,红藻物种的数量从潮间带向上迅速减少。然而,从潮间带下部向下,它们是物种多样性的主力(在罗斯科夫地区占500多个大型藻类物种的一半以上,[6])。当它们下降到常年被淹没的潮下带时,这些藻类会受益于它们的红色素藻红蛋白,这些藻红蛋白能捕获海水传输的最后波长的光[7]

  红藻的形态多样性、生物多样性和生态多样性非常高,但它们的长度很少超过 30 厘米 – 棕榈藻(Palmaria palmata)(图 14B)—同时平均生物量低。在锯齿墨角藻带的岩石上,可以观察到大块的类似形状的长角墨角藻(Chondrus crispus,图16B)和星形墨角藻(Mastocarpus stellatus);这些藻类在布列塔尼语中称为“liken”或“pioka”,经手工采摘后用来提取卡拉胶,是一种重要的工业和食品胶凝剂。

  潮间带的中部到下部环境海水扰动强烈,没有褐藻生存,我们只能在夏季零星地观察到一种叫Rivularia bullata的小的表面蓝绿色的蓝藻细菌,或者一种名为Nemalion helminthoides的红色藻类,它有柔软、浅红、轻微分枝的轴。

3.2. 无分区的岩石盆地

环境百科全书-生命-海岸
图17.A.潮间带上部有压缩的绿藻Ulva (= Enteromorpha)和腹足类(Monodonta lineata);B.潮间带中部有棕色藻类,分叉双歧双胞藻Bifurcaria bifurcate,以及各种钙化的、分枝的或结壳的珊瑚藻(红藻) Corallinaceae,颜色为浅粉色。(图17)A,潮间带上部有压缩的绿藻和腹足类单齿藻;B.潮间带内有棕色的分叉双歧藻类和各种钙化的、分枝的或被壳的珊瑚类(红藻)。

  基岩盆地往往充满水,扰乱了前滨的分带;它们为不能耐受暴露在空气中脱水的各种物种提供了有利的生境[1][2]。它们在前滨的水位、大小、深度和光照会影响它们的分布。脱盐、温度较高或缺氧快速的高处的盆地物种稀少,主要是绿藻(图17A)。在中潮水位以下的地方生活着各种各样的动物:海葵、虾、腹足类动物、小鱼以及各种藻类,这些生物通常生活在盆地的下面和外面。图17B展示了褐藻(Bifurcaria bifurcata)(15厘米长)和各种具壳状钙化外壳的珊瑚藻科的红藻;后者不会离开盆地底部,从而避免脱水。

3.3. 固定或轻微活动动物的堆积和适应[1]

  滨螺科的腹足类分布如下(图18): 宽尾角螺Melaraphe neritoides)在潮上带,黑线带螺Littorina nigrolineata)和糙带螺L. rudis)在潮间带上部,厚壳玉黍螺Littorina littoralis)和(L. littorea)(也称winkle)在潮间带中部到潮下带上部;第一种很少在水中,其呼吸和排泄生理机能与陆地蜗牛相似。其他腹足类动物的四肢和齿肢也是交错的。此外,狗岩螺Nucella lapillus),也称狗螺,在恶劣的环境条件下会形成比良好环境条件下更厚的外壳。

环境百科全书-生命-海岸
图18.三个岩质前滨的例子,从左到右:A.Melaraphe neritoides,5毫米,高潮区岩石裂隙中;B. Littorina nigrolineata,1-1.5厘米,在上中海岸岩石上;C.Littorina littoralis,1厘米,潮间带中部到下部食用墨角藻Fucus

  甲壳类中,藤壶附着在岩石上,由坚硬的石灰质壳板保护; 它们也或多或少地形成规则的带:顶部是短毛披碱草和星形披碱草(Elminius modestusChthamalus stellatus)(图6),中部是北方藤壶(Balanus balanoides),底部是多孔藤壶(Balanus perforatus)和波状藤壶(B. crenatus)。

  为了避免被海浪冲走,动物永久地固着在岩石或藻类上(图5、6和19),有时由贻贝的细丝或吸盘固定,或在遇到困难时卡在裂缝中(图18A)。除了少数例外,大多数动物的生物活动都发生在被海水淹没或环境潮湿时;低潮时,它们动作会放慢,例如腹足类会合上厣或紧紧吸附在岩石上。

4. 多样化的食物链

  基岩海岸的植物和动物带形成了各种并列和相互关联的群落,各种食物链在一个完整的食物网中运作。它们的底部是固定的大型藻类、附着在岩石上的微藻类和来自海洋流动的浮游微藻类的初级生产者

环境百科全书-生命-海岸
图19.附着在藻类上的两个动物例子:A、滤食性苔藓动物Membranipora membranacea;B、捕食性水螅类Obelia geniculata 图片来源:©S.坦桑尼亚雷拉-帕加农。

  次生动物生产者的类型多种多样:

  海岸线上的腹足动物、帽贝(图6和18)、海胆是固定的食藻动物,大小不一;海绵、贻贝、藤壶(图6)、苔藓虫(图19A)、海鞘(图5)和一些蠕虫都是浮游生物和有机碎屑的滤食者

  许多捕食者、海葵和水螅(图19B)、甲壳类动物和鱼类捕捉活动的猎物。狗岩螺会刺穿固着的藤壶和软体动物。其他的腹足动物则以固定在岩石上或海藻上的动物为食;

  许多甲壳类动物,如螃蟹,是食腐动物食碎屑动物(以尸体或各种有机碎屑为食)。

环境百科全书-生命-海岸
图20.马尾藻(Sargassum muticum)的局部视图,这是一种来自太平洋的大型棕色外来海藻,生活在中、下海岸的边缘,处于平静模式

  总之,应该指出的是,预期的海平面上升可能会通过侵蚀改变海岸,并通过引起某些生物的耗竭而影响这里出现的分区。此外,在过去的一个世纪里,由于牡蛎育苗的交换或全球化的运输,许多藻类或动物入侵了欧洲海岸。例如,大型褐藻马尾藻(Sargassum muticum,图20)于20世纪70年代末从日本传入;它在平静的基岩盆地和河道上定居,在那里它能够融入现有的生物带而不会造成任何问题,而在泥泞的沙质地区,它会附着在小鹅卵石或牡蛎养殖园的柱子上,造成更多问题。

 


参考文献和注释

封面图片。布列塔尼的岩石海岸在退潮时受到波浪的影响。 [照片 © J. Joyard]。除非另有说明,本文中的照片均由 Olivier 或 Céline Manneville 拍摄。

[1] Turquier Y. & Loir M. (1981) Connaître et reconnaître la faune du littoral. OUEST-FRANCE, 330 p. (in french)

[2] Cabioc’h J., Floc’h J.-Y., Le Toquin A., Boudouresque C.-F., Meinesz A. & Verlaque M. (2006) Guide des algues des mers d’Europe. DELACHAUX-NIESTLE, 272 p.

[3] Connell J.H. (1961) The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus, Ecology, 42, 710-723.

[4] Asta J., Van Haluwyn C.& Bertrand M. (2016) Guide des Lichens de France – Lichens des roches. BELIN, 384 p. (in french)

[5] Arzel P. (1987) Les goémoniers. Le Chasse-Marée, 305p. (in french)

[6] http://www.sb-roscoff.fr/INVENTAIRES/InvAlgues/index.algues.php?

[7] Selosse M.A. (2000) Les algues de la zone intertidale et leur zonation : des idées reçues aux données écologiques. Biologie-Géologie, Bulletin de l’APBG, 2000/4, p.773-801. (in french)


环境百科全书由环境和能源百科全书协会出版 (www.a3e.fr),该协会与格勒诺布尔阿尔卑斯大学和格勒诺布尔INP有合同关系,并由法国科学院赞助。

引用这篇文章: MANNEVILLE Olivier (2024年2月23日), 岩石海岸的生物多样性:分区和生态关系, 环境百科全书,咨询于 2024年10月4日 [在线ISSN 2555-0950]网址: https://www.encyclopedie-environnement.org/zh/vivant-zh/biodiversity-on-rocky-coasts-zoning-and-ecological-relationships/.

环境百科全书中的文章是根据知识共享BY-NC-SA许可条款提供的,该许可授权复制的条件是:引用来源,不作商业使用,共享相同的初始条件,并且在每次重复使用或分发时复制知识共享BY-NC-SA许可声明。

Biodiversity on rocky coasts: zoning and ecological relationships

The Atlantic rocky coasts, subject to tidal sway, make it easy to observe the organisms that colonize them. Depending on the level and living conditions, various lichens or large brown algae dominate and form horizontal belts. Less clearly, some fixed or slightly mobile animals are also arranged in belts. Other animals and algae are distributed more irregularly through basins, channels and rocky overhangs. The specific diversity decreases upwards in the emerged area and also when conditions become too difficult: too turbulent, too sunny or with very variable salinity. Organisms on rocky coasts thus have many biological adaptations to emergence or agitation and many specializations and interrelationships related to nutrition.

The Atlantic coasts are subject to the tidal phenomenon; part of the coastline is thus exposed over a variable area that depends on the slope and tidal range. Organisms living in this tidal balancing zone and in the surrounding areas therefore have to withstand a very particular and quite variable environment over time. Depending on the characteristics of the mineral substrate, the coastlines are very different in appearance and correspond to distinct ecosystems.

Thus, on rocky coasts, the subject of this article, algae, especially brown algae (see focus Algae and their classification), and lichens fixed on the rock most often dominate and are distributed in horizontal belts, from the terrestrial environment to the marine environment always immersed; this is why we will insist on these structural species very easy to observe. Some fixed or slightly mobile animals also have such a vertical zoning, while more mobile species (fish, shrimps, various molluscs) follow the movements of the sea or take refuge in basins or sheltered blocks to survive.

Encyclopédie environnement - biodiversité des côtes rocheuses - Herbier de Zostera marina
Figure 1. Meadows of Zostera marina, eelgrass, a marine flowering plant, on low sandy levels. Due to its habitat and morphology (especially the presence of long ribbon-like leaves), many people think that eelgrass is an algae. In fact, it has roots anchored in the sand. Eelgrass beds have a high biological diversity.

On sandy or muddy coasts, the zonation is much less clear-cut, as the animals live mainly buried there, especially at low tide [1]. There are fewer plants, apart from local flowering rooted plants: Spartina, Salicornia or other flowering plants in calm high levels and eelgrass (Figure 1) in very low levels. Algae are practically absent due to a lack of stable fixation; the fauna of these environments is very different from that of rocks. An entire article would be needed on these ecosystems, which are organized and function very differently from those of rocky coasts.

1. Ecological factors and their effects

Many ecological factors, and the resulting physico-chemical gradients, directly affect the distribution of living organisms in marine coastlines, and these factors are most often correlated with each other, sometimes complicating interpretation.

1.1. Duration of emergence and dehydration

Encyclopédie environnement - biodiversité des côtes rocheuses - Une côte rocheuse bretonne à marée basse et marée haute
Figure 2. A rocky coast from Brittany at low tide (A) and high tide, 6 hours later (B).

This factor is essential on the so-called tidal coasts of the Atlantic and the English Channel (and very secondary in the Mediterranean) (see The tides). Twice in about 24 hours, the intertidial zone is alternately submerged at high tide and emerged at low tide (Figure 2). This causes strong constraints on flora and fauna, mainly of marine origin. Moreover, according to the lunar and seasonal cycles, the amplitude of tidal sway varies greatly: important towards the full moon or the new moon and towards the equinoxes, it is quite low in the first and last quarters of the moon and towards the solstices [1] (see Light cycles and living organisms).

Thus, organisms living in the highest levels of the coastline have been selected to resist a long emergence from the marine environment at least 80% of the time. During emergence, they are exposed to direct sunlight, temperature variations, osmotic stress related to fresh rainwater or desiccation. In addition, in the air, marine wildlife can no longer absorb dissolved oxygen from the water; this implies that animals can keep some water around them or, more rarely, change the way they breathe [1]. These conditions are more stable and less constraining for species at the bottom of the foreshore; they are often the same species as those in the permanently submerged area [1].

The tidal range, or maximum difference in level between the lowest and highest seas, is typical of a given place and depends on the conformation of the coasts: 14 m in the bay of Mont Saint Michel, 8.50 m in Roscoff, about 6 m in Le Havre and Nantes, just over 4 m in Biarritz. The larger the tidal range, the wider and more diversified tidal swing areas and the wider the belts, thus understanding the interest of the French coasts of the Western Channel, from Cherbourg to Brest.

Encyclopédie environnement - biodiversité des côtes rocheuses - Un estran rocheux à marée basse
Figure 3. A rocky foreshore at low tide, with its different levels; the infralittoral is not present in this photo.

We therefore define four levels on our marine coasts [1],[2], depending on the marine influence and the duration of emergence (Figures 3 & 7):

  • the adlittoral level in direct continuity with terrestrial ecosystems and subject to salt spray;
  • the supralittoral level, which is only submerged during very high tides and storms;
  • the midlittoral floor constantly swept by the tides and subdivided into three levels;
  • the infralittoral level, the upper level of which only emerged during high tides and for less than an hour at a time. The latter extends up to 10 to 30 m under the sea, depending on the illumination of the sea bed.

The further down the rocky foreshore you go, the larger and more diversified the algae are and the more species there are in the fauna as well; it is for this reason that fishermen on foot wait for the high low tides to hunt or collect lobsters, seeweeds, periwinkles and abalones. Biomass and productivity are also highest in the infralittoral region.

1.2. Water agitation

This factor, linked to currents and waves, depends strongly on the orientation and conformation of the coasts: strong agitation on rocky capes exposed to the west or at the foot of cliffs and little agitation at the bottom of sheltered bays and estuaries. This has a great influence on organisms. Indeed, certain species of algae, in thalleDescribes the relatively simple vegetative apparatus of primitive plants (algae, lichens, certain bryophytes…) compared to that of evolved plants that have a cormus with stem, roots and leaves. too fragile or very long, are shredded or torn off by strong waves and some animals, poorly fixed or with too soft a body, cannot survive in beaten environments, while others need highly oxygenated beaten water to survive. It should be noted that the same coastal site can be very beaten in the upper mid-coast (by the high tide swell which arrives without obstacles) and relatively calm in the lower mid-coast or the infralittoral (where the waves are slowed down by various obstacles at low tide).

Encyclopédie environnement - biodiversité des côtes rocheuses - Effets de l’agitation de la mer sur les organismes du médiolittoral
Figure 4. Effects of sea agitation on medium-coastal organisms: A, very beaten mode, without algae and with fixed animals; B, medium beaten mode, with Fucus serratus and various red algae on the shaded edge; C, calm mode, with Ascophyllum nodosum.

Depending on the effects observed on organisms (species present, size and biomass), three modes of agitation can be identified, with intermediates: “very beaten”, “moderately beaten” and “calm” (Figure 4). We see that the more the midlittoral is beaten, the less algal biomass there is and this can go as far as the bare rock without any organisms.

1.3. Illumination

Encyclopédie environnement - biodiversité des côtes rocheuses - Dendrodoagrossularia ou groseille de mer
Figure 5. Overhang of shaded rock with Dendrodoa grossularia or sea gooseberry, social ascidia.

Algae and lichens need light for photosynthesisBioenergetic process that allows plants, algae and some bacteria to synthesize organic matter from the CO2 in the atmosphere using sunlight. Solar energy is used to oxidize water and reduce carbon dioxide in order to synthesize organic substances (carbohydrates). The oxidation of water leads to the formation of O2 oxygen found in the atmosphere. Photosynthesis is at the base of autotrophy, it is the result of the integrated functioning of the chloroplast within the cell and the organism., but too much light is often harmful to organisms used to be protected by a sometimes cloudy water layer. At the mid-coastal level, some species therefore take refuge, to protect themselves from light, under other larger algae – the case of the red alga Catenella cespitosa of the upper mid-coastal – at the base of the rocks, which are always wet (Figure 4B) or under rocky overhangs. Many green algae tolerate high levels of light (see Figure 17A below), as well as brown algae at higher levels. Direct sunlight can also be a problem for many animals, such as sponges and ascidians (Figure 5), as it is accompanied by dehydration and heating.

1.4. Other physicochemical factors

With regard to the nature of the support, most large algae live on rocks or pebbles, fixed by holdfasts (see below Figure 14B) or false roots, and die fairly quickly if they detach themselves from them. The rocky coasts are therefore their favourite biotope. Granite, gneiss and coarse sandstone, with a rough surface, are the most favourable, while smooth sandstone or marly limestone and chalk, easily broken up by the sea, are less favourable. Some small species of algae are attached to other algae. Many animals survive only by being fixed on various solid supports (Figures 5 & 6 and see below, Figure 19): many gastropods, mussels, barnacles, sea anemones, sponges, ascidians…

During the flood, wide temperature variations and freezing are harmful to most marine organisms, which can only live at the bottom of the foreshore. Moreover, the flora and fauna are not identical between Biarritz and Dunkirk, as some species prefer fresh water; this is the case of large brown algae.

In estuaries, water salinity is lower and above all much more variable, eliminating many marine species. The water is also turbid, as it is loaded with mud, and many algae no longer have enough light in the low levels. Global biodiversity is therefore decreasing sharply, even if productivity remains very high.

1.5. Interspecific competition

Figure 6. A, Diagram showing an example of competition between two species of barnacles. Although the base niche of Chthamalus stellatus extends over the entire area between high and low tide levels, the effective niche is restricted by the presence of larger Balanus balanoides. [Photo credit: Chthamalus by Michael Maggs (CC BY-SA 3.0) & Balanus, by Auguste Le Roux (CC BY-SA 4.0-3.0-2.5-2.0-1.0), via Wikimedia Commons]. B, Beaten rock, without algae, of the middle coast, housing only a marine lichen in black cushion, Lichina pygmaea, a gastropod, Patella vulgata, and a fixed crustacean, the barnacle Chthamalus stellatus, very abundant here on the right of the picture. These animals have a shell or solid calcareous plates and are well attached to resist waves.
Competition, for place or light, plays an important role in the zoning of organisms; they are the most adapted to local ecological conditions, and sometimes the first to arrive, which dominate leaving little space for others. This is proven by the fact that the presence of a competitive species in a given region forces another to restrict its place on the coast. Figure 6A shows the case of two barnacles species: in the presence of Balanus balanoides, Chthamalus stellatus is confined to the upper levels, whereas it can live lower; these two species feed by water filtration [3].

Figure 6B illustrates another case of competition in the middle-coastal region: the strong agitation of the environment excluded here seeweeds, which allows the installation of the short cushions of the small Lichina who needs light; the barnacle larvae then settle only in areas without lichen; finally, as there are many barnacles fixed, there is little space left for the pads to scrape the rock !

2. Lichen or brown seaweed belts

By combining altitudinal zonation in stages and the various modes of water agitation, we can develop the table below (Figure 7) which presents the various plant belts of our rocky coasts [2],[4].

Figure 7. Layering of algae and lichens according to average water agitation. The colours of the names correspond to brown algae (brown), red algae (red), cyanobacteria (blue-green) and lichens. The dominant species are in upper case and the others in lower case. The percentages, on the left, correspond to the emergence times of the various levels: 0% at the level of very high seas, 50% in the middle of the shore and 100% at the level of very low seas.

2.1. Lichens at upper littoral stages

Lichens are originally terrestrial organisms. This is why, unlike algae and marine animals, their specific diversity decreases as they descend towards the sea. Many species of lichens can be found on coastal rocks, some of which also live inland (Xanthoria parietina) and others are typical of the marine coastline (Verrucaria maura, Lichina spp.) [3].

Encyclopédie environnement - biodiversité des côtes rocheuses - ceintures de lichens et d’algues de l’adlittoral au médiolittoral supérieur
Figure 8. Lichen and algae belts from the adlittoral to the upper midlittoral.

Lichen belts can be seen from afar due to their high contrasted colours (Figure 8). Above, in the adlittoral layer, where there are also a few flowering plants that support the salt of the sea spray, the light green tufts of the Ramalina, the orange-yellow foliage thallus of the Xanthoria and the various crust thallus, ranging from white to dark grey or brown, of many genera of lichens (Figure 9A) are most notable.

 Encyclopédie environnement - biodiversité des côtes rocheuses - Lichens soumis aux embruns de l’adlittoral : Ramalinaspp
Figure 9. A, Lichens exposed to adlittoral spray: Ramalina spp. in grey-green tuft, Xanthoria spp. in orange patches, Ocrolechia parella in grey crust; B, Lichens of the supralittoral, sometimes covered by the sea: Verrucaria maura in black and Caloplaca spp. in yellow.

The supra-coastal layer, covered at very high tides, is colonized by the crusts of Caloplaca marina and C. maritima scattered in an almost continuous black belt of Hydropunctaria (= Verrucaria) maura (Figure 9B). This last fine-crusted lichen is often mistaken for a remnant of oil spills! Among the rare lichens in the mid-coastal zone are Lichina pygmaea, which live in very beaten environments (Figure 6).

On very rough coasts, the adlittoral and supralittoral levels extend upwards (more than 20 m on the cliffs of Finistère, Quiberon or La Hague) with very wide lichen belts; the very harsh conditions of these coasts favour lichens, whose symbiosis of filamentous fungus, green algae or cyanobacteria makes them more resistant compared to flowering plants. On the other hand, in wave-sheltered estuaries, all these belts together only reach a height of 20 cm; calm conditions even allow oaks to approach the sea and soak their branches at high tide.

2.2. Brown algae of medium and low levels

Encyclopédie environnement - biodiversité des côtes rocheuses - Pelvetiacanaliculata et Fucusspiralis
Figure 10. Pelvetia canaliculata (A) and Fucus spiralis (B), of the upper midlittoral not too beaten.

Brown algae or Phaeophycea, Fucales and Laminariales, largely dominate rocky foreshores by their biomass [2]. They were once used to extract soda by burning it in ovens or to fatten fields, under the name of varech in Normandy and goëmon in Brittany [5] i.e. wrach or kelp in english. They therefore form the characteristic belts of the mid- and sub-littoral levels. Their size, as well as their biomass, increases as they descend: 10 cm for Pelvetia, about 1 m for Ascophyllum and Sargassum and up to 5 m for Himanthalia and Laminaria hyperborea. The floats of some algae allow them to stand vertically at high tide, towards the light, in the case of Ascophyllum and Fucus vesiculosus.

Encyclopédie environnement - biodiversité des côtes rocheuses - Ascophyllumnodosum
Figure 11. Ascophyllum nodosum, especially common in the calm midlittoral, and its parasitic red algae Vertebrata lanosa.

The upper midlittoral (about 70-80% of the time emerging) consists of two algae belts that can withstand desiccation very well and can lose up to 75% of their water without dying; these are Pelvetia canaliculata (Figure 10A) and Fucus spiralis (Figure 10B); these algae are absent in very rough environments (Figure 6).

Encyclopédie environnement - biodiversité des côtes rocheuses - Fucus vesiculosus du médiolittoral
Figure 12. A, Fucus vesiculosus of the middle medolittoral lightly beaten to calm, with floats; B, Fucus vesiculosus var. linearis of the midlittoral well beaten, without floats.

The average midlittoral (about 50% of the time emerging) is characterized by Ascophyllum nodosum and Fucus vesiculosus. The first (Figure 11) is very abundant in calm mode where it forms thick mats and is often parasitized by a red alga, Vertebrata lanosa. Fucus vesiculosus (Figure 12A) dominates in more beaten environments, but is missing in heavily beaten areas or has a special form of accommodation that is narrower, tougher and without floats (Figure 12B).

Encyclopédie environnement - biodiversité des côtes rocheuses - Fucus serratus, à thalle denté
Figure 13. Fucus serratus, toothed thallus, of the lower midlittoral.

Finally, most of the lower midlittoral (about 30 to 20% of the time emerging) is colonized by Fucus serratus, still without floats (Figure 13).

The base of the lower midlittoral and the upper infralittoral (less than 10% of the time emerging) host the large thalli of Saccharina latissima (= Laminaria saccharina) (Figure 14A) in a calm environment, from  Saccorhiza polyschides (Figure 14B) with flattened and soft stipeStream of algae, which lacks conductive vessels., edible Himanthalia elongata (Figure 15) or sea bean, with very long narrow and dichotomousTwo-part branching pattern at each growth level. More generally, characterizes the division of something into two clearly opposed elements axes, and Laminaria digitata (Figure 15) with a smooth and flexible cylindrical stipe, in more or less beaten environments.

Encyclopédie environnement - biodiversité des côtes rocheuses - Saccharinalatissima Saccorhizapolyschides Palmariapalmata
Figure 14. A, Saccharina latissima with long undulating thallus, of calm mode; B, Saccorhiza polyschides, attached by bulbous complex holdfast and with flattened stipe, and Palmaria palmata, large red algae at the top right, at the limit of the lower midlittoral rather beaten.
Encyclopédie environnement - biodiversité des côtes rocheuses - Himanthaliaelongata
Figure 15. Himanthalia elongata, with narrow dichotomous thallus, and Laminaria digitata, with deeply torn blades and flexible cylindrical stipe, two species typical of the upper infralittoral.

The last belt, in the infralittoral never or very rarely emerged, consists of Laminaria hyperborea, with a stiff cylindrical stipe. The biomass of these algae is sometimes very high and is said to form “underwater forests”. Between Roscoff, Ouessant and Le Conquet, this species forms, with other kelps, the largest and richest algae sector in Europe (the Seaweed Coast), where a semi-industrial exploitation takes place for alginate extraction, among others.

3. Distribution of other organisms

3.1. Red and green algae

Other algae do not form real belts, continuous or regular [2].

Encyclopédie environnement - biodiversité des côtes rocheuses - Laitue de mer, Ulvaspp., ici fixée sur les rochers de bas niveau
Figure 16. A, Sea lettuce, Ulva spp., here fixed on low level rocks; B, Chondrus crispus, red algae of the lower midlittoral

Green algae, or Chlorophyceae, are mostly opportunistic and grow rapidly where there is little competition; they often withstand strong sunlight, variations in salinity or temperature and also the abundance of man-made nitrates. Among them, Ulva spp. (Figure16A) or sea lettuce proliferate during the summer on some rocks and then detach from them and accumulate in calm bays where they rot and producing foul smelling decomposing green tides (see Nitrates in the Environment).

On the other hand, red algae, or Rhodophyceae, do not tolerate too much light or significant desalination; from dark red to almost black sometimes in winter, they turn green during the summer, because the red pigments are destroyed by UV rays. For this reason, the number of red algae species decreases very rapidly upwards, from the middle mid-coastal. However, from the lower mid-coastal down, they form most of the specific diversity (more than half of the more than 500 macroalgae species in the Roscoff region, [6]). As they descend into the ever-submerged infralittoral, these algae benefit from their red pigment, phycoerythrin, which captures the last wavelengths of light transmitted by seawater [7].

The morphological, biological and ecological diversity of Rhodophyceae is very high, but they very rarely exceed 30 cm in length – Palmaria palmata (Figure 14B) -, while producing average to low biomass. On the boulders of the Fucus serratus belt, large, spots of similarly shaped Chondrus crispus (Figure 16B) and Mastocarpus stellatus can be observed; these algae, called liken or pioka in Breton, are harvested by hand to extract carrageenans, important industrial and food gelling agents.

In the medium to lower middle coast, very beaten and without brown algae, we can observe, only during the summer and in a dispersed way, the small blue-green skins of a cyanobacterium called Rivularia bullata or the soft, reddish and slightly branched axes of Nemalion helminthoides, a red alga.

3.2. Non-zoning rocky basins

Encyclopédie environnement - biodiversité des côtes rocheuses - Cuvette du médiolittoral supérieur hébergeant Ulva
Figure 17. A, Upper midlittoral bowl housing Ulva (= Enteromorpha) compressed, green algae, and the gastropod Monodonta lineata; B, Middle midlittoral bowl with a brown alga, Bifurcaria bifurcate, and various calcified, branched or encrusted Corallinaceae (red algae), pale pink in colour.

The rocky basins, always filled with water, disturb the belt zoning of the foreshore; they offer a favourable biotope for various species that do not tolerate dehydration due to the exposure [1],[2]. Their level on the foreshore, their size, their depth and their illumination will condition their stands. The high level basins, which are desalinated, heated or lose their oxygen quickly, are poor in species, with mostly green algae (Figure 17A). Those below mid-tide level support a variety of animals: sea anemones, shrimps, gastropods, small fish, as well as various algae that normally live below and outside the basins. Figure 17B shows the brown alga Bifurcaria bifurcata (15 cm long) and various crustose calcified red algae of the Corallinaceae family; the latter do not leave the bottom of the basin and thus avoid dehydration.

3.3. Stacking and adaptations of fixed or slightly mobile fauna [1]

The gastropods of the Littorinidae group are spread as follows (Figure 18): Melaraphe neritoides in the supralittoral, Littorina nigrolineata and L. rudis in the upper midlittoral and Littorina littoralis and L. littorea (or winkle) from the middle midlittoral to the upper infralittoral; the first one, rarely submerged, has a respiratory and excretory physiology close to land snails. The various limbs and gibbles, other gastropods, are also staggered. In addition, Nucella lapillus, or dog whelk, has a thicker shell in beaten mode than in quiet mode.

Encyclopédie environnement - biodiversité des côtes rocheuses - Trois exemples de littorines de l’estran rocheux
Figure 18. Three examples of rocky foreshore Littorinidae, from left to right: A, Melaraphe neritoides, 5 mm, supralittoral cracks; B, Littorina nigrolineata, 1 to 1.5 cm, on rocks of the upper midlittoral; C, Littorina littoralis, 1 cm, medium to lower midlittoral Fucus grazer.

In the crustacean group, barnacles are attached to the rock and protected by solid limestone plates; they also form more or less regular belts: Elminius modestus and Chthamalus stellatus (Figure 6) at the top, Balanus balanoides in the middle and Balanus perforatus and B. crenatus at the lowest levels.

To avoid being swept away by waves, animals are permanently glued to the rock or algae (Figures 5, 6 and 19), more or less temporarily fixed by filaments for mussels and a suction foot for limbs or stuck in cracks in difficult times (Figure 18A). With few exceptions, most of the animals’ biological activity takes place during immersion or when the environment remains wet; at low tide, they live in slow motion, closing their operculum or pressing against the rock, in the case of gastropods.

4. Varied food chains

The plant and animal belts of the rocky coasts form various juxtaposed and interrelated communities, with various food chains operating in an integrated food web. At their base are the primary producers of fixed macroalgae, microalgae attached to rocks and also plankton microalgae from the marine flow.

Encyclopédie environnement - biodiversité des côtes rocheuses - Deux exemples d’animaux fixés sur les algues
Figure 19. Two examples of animals attached to algae: A, Membranipora membranacea, filter feeder bryozoan; B, Obelia geniculata, predatory hydrarian. Photos: © S. Tanzarella-Paganon.

Secondary animal producers are of very varied types:

  • gastropods, patellae and coastlines (Figures 6 and 18), and sea urchins are fixed algae grazers, small or large; sponges, mussels, barnacles (Figure 6), bryozoans (Figure 19A), ascidians (Figure 5) and some worms are plankton and organic debris filterers;
  • many predators, anemones and hydrarians (Figure 19B), crustaceans and fishes, catch mobile preys. The dog whelk pierces the fixed barnacles and molluscs. Other gastropods graze on animals fixed on rocks or those stuck to algae;
  • finally, many crustaceans, such as crabs, are scavengers or detritus feeders (eaters of corpses or various organic detritus).
Encyclopédie environnement - biodiversité des côtes rocheuses - Vue partielle de Sargassummuticum
Figure 20. Partial view of Sargassum muticum, a large brown alien seaweed from the Pacific and living at the limit of the medium- and infralittoral in calm mode.

In conclusion, it should be noted that the expected rise in sea level could modify both the coasts by erosion and impact the zoning presented here by causing the depletion of some organisms. In addition, many algae or animals have invaded the European coasts over the past century, thanks to the exchange of oyster spat or globalized shipping. Examples include the large brown algae Sargassum muticum (Figure 20), which arrived from Japan in the late 1970s; it colonizes both calm rocky basins and channels, where it has been able to insert itself into existing belts without causing problems, and muddy sandy areas where it attaches itself to small pebbles or oyster park poles, causing more problems.

 


References and notes

Cover image. A rocky coast of Brittany subjected to waves at low tide. [Photo © J. Joyard]. Unless otherwise indicated, photos in this article are by Olivier or Céline Manneville.

[1] Turquier Y. & Loir M. (1981) Connaître et reconnaître la faune du littoral. OUEST-FRANCE, 330 p. (in french)

[2] Cabioc’h J., Floc’h J.-Y., Le Toquin A., Boudouresque C.-F., Meinesz A. & Verlaque M. (2006) Guide des algues des mers d’Europe. DELACHAUX-NIESTLE, 272 p.

[3] Connell J.H. (1961) The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus, Ecology, 42, 710-723.

[4] Asta J., Van Haluwyn C.& Bertrand M. (2016) Guide des Lichens de France – Lichens des roches. BELIN, 384 p. (in french)

[5] Arzel P. (1987) Les goémoniers. Le Chasse-Marée, 305p. (in french)

[6] http://www.sb-roscoff.fr/INVENTAIRES/InvAlgues/index.algues.php?

[7] Selosse M.A. (2000) Les algues de la zone intertidale et leur zonation : des idées reçues aux données écologiques. Biologie-Géologie, Bulletin de l’APBG, 2000/4, p.773-801. (in french)


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引用这篇文章: MANNEVILLE Olivier (2019年4月23日), Biodiversity on rocky coasts: zoning and ecological relationships, 环境百科全书,咨询于 2024年10月4日 [在线ISSN 2555-0950]网址: https://www.encyclopedie-environnement.org/en/life/biodiversity-on-rocky-coasts-zoning-and-ecological-relationships/.

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