Species point records from 1986 OPRU HRE Plymouth Harbour & Yealm Estuary survey

Plymouth and the Yealm Estuary are situated on the south coast of Devon. The Plymouth area includes a complex of marine inlets, the largest of which is the Tamar which is tidal for about 30 km and is joined by the Rivers Tavy and Lynher. The Tamar empties into Plymouth Sound which is an open bay with an artificial breakwater at its entrance and Drake's Island to the northwest. The River Plym empties into the Northeast of Plymouth Sound. The Yealm Estuary is situated to the east of Plymouth Sound and is tidal for 6.5 km. Plymouth Sound is an important commercial harbour, and the Devonport Royal Naval Dockyard is situated in the lower Tamar Estuary. The area has a long history of marine biological study, both for research and education. Staff from the Marine Biological Association at Plymouth have carried out research in the area since 1884. Research is also carried out by staff at the Institute for Marine Environmental Research, and Plymouth Polytechnic uses the area for student projects and practicals. The coastline of Plymouth Sound is steeply sloping and almost entirely rocky. The coastlines of its associated estuaries are generally more gently sloping, and contain large expanses of mud flats. Rocky outcrops are also present and steep rock slopes occur on some river bends. The Yealm Estuary is a narrow steep sided inlet with some branches. Underwater a steep sided channel winds a course through Plymouth Sound from the entrance to the Tamar and out past the breakwater. Depths of up to 40 m are present in this channel. The Tamar is the main receiver of freshwater inputs and salinity does not normally reach fully marine conditions until it enters Plymouth Sound. The northern area of Plymouth Sound is influenced by this freshwater input. Freshwater input to the Plym and the Yealm is low. Areas of strong tidal streams are present at the narrow rocky entrance to the Tamar and across the `bridge` between Drake's Island and the western side of the sound. The inner area of the sound is sheltered by the breakwater at its entrance, but the outer sound, particularly on the eastern coast, is subject to strong wave action from prevailing south-westerly winds. The Yealm is sheltered by a sandbar at its entrance. The present survey aimed to collect further information on the marine habitats and communities which had not previously been described or had not been sampled since the early 1900's. The abundance of species living on hard surfaces and visible on the surface of sediments was recorded in situ. Intertidal sediment fauna was collected in 0.01 and 0.1 m2 cores and by digging, and samples were sieved over 0.5 mm, 1 mm and 5 mm mesh sieves. Subtidal sediments were sampled using a pipe dredge and, outside the breakwater, with a suction sampler. The samples were sieved over a 1 mm mesh. Animals were picked out of the sediments, identified and counted. Photographs were taken to illustrate habitats, communities and species. A series of aerial photographs was taken during low water spring tide level in April. Habitats and communities present were classified into 29 intertidal types (22 in the Plymouth area and 7 in the Yealm) and 28 subtidal types (22 in the Plymouth area and 6 in the Yealm). Descriptions are given of each of these and the abundance of species is shown in the tables. The distribution of habitats is discussed and the subtidal substratum types are listed. Nine major ecological zones are suggested, and described, for the Tamar and Plymouth Sound, on the basis of salinity, wave exposure and the communities and species found in them. These zones are termed-Open Sea, Open Coast, Sheltered Bay, Outer Estuarine, Lower Estuarine, Central Estuarine, Upper Estuarine, Riverine-Estuarine Transition and Riverine. The habitats and communities surveyed are compared with those in other marine inlets and with previous marine biological studies in the area. The area of Plymouth Sound and the Tamar is much more extensive than most other marine inlets studied although it includes many similar habitats, communities and species. The Yealm is small but compares very well with other inlets. The main characteristics of the Plymouth area and Yealm estuary are much as previously described in the Plymouth Marine Fauna (1957) and published work from the first half of this century (and late nineteenth century). For some areas our assessments rely on some part on this previous work. However, this survey has found a number of changes, and communities on rocky sublittoral habitats have been adequately described for the first time. There have also been a number of species that have been recorded for the first time. These include species of the red algae, Schmitzia, and a variety of polychaete worms, including Pisione remota, Ampharete lindstroemi, and Protodorvillea kefersteini. The seapen Virgularia mirabilis was also recorded from north of the breakwater, where it has not previously been seen. Apoglossum ruscifolium was commonly recorded in the Hamoaze on this survey but not by Johnson in 1890. The distribution of Fucus vesiculosis in the Tamar appears to have extended northwards since the records of Percival (1929), while that of Cordylophora lacustris appears to have extended downriver. The former suggesting a reduced freshwater input, but the latter an increase. A number of minor changes were also noted in Kithching's gulley outside the entrance to the Yealm. The scientific interest and nature conservation importance of the area has been assessed using standard criteria and the conservation importance of the habitats and communities in the area have been provisionally graded as of Local, Regional, national or International importance. Species of particular scientific interest identified during the survey have been noted and their conservation importance provisionally graded as of Regional, National or International importance. For the general assessment of scientific interest and nature conservation importance the area has been considered in six separate parts:- The Open Sea and Open Coast which is most notable for the Mediterranean-Atlantic species found in deep water offshore; Outer Plymouth Sound which has some interesting rocky shore habitats, particularly the rockpools, and large areas of very rich and interesting subtidal sediment communities; Inner Plymouth Sound which has some very unusual limestone bedrock communities characteristic of rias and with interesting boring species; the Cattewater and Plym Estuary which have some rich mudflats but are generally of lesser importance; the Tamar and Lynher Estuaries which are most notable for the presence of rocky substrata extending along the estuarine gradient and the rich current swept cobbles and pebbles in the lower estuary; and the Yealm Estuary which is of outstanding interest due mainly to the high diversity of habitats and communities which are almost entirely natural. Much of Plymouth Sound and its associated estuaries are affected by human activity, but in the Yealm Estuary current levels of recreational activity do not appear to be damaging its naturalness, except for the presumably high levels of organotin from antifouling paints. Records currently considered sensitive have been removed from this dataset.

普利茅斯与耶尔姆河口的地理位置位于德文郡的南部海岸。普利茅斯地区包括一系列复杂的海洋潟湖，其中最大的是塔马尔河口，该河口潮汐范围约30公里，由塔维河和林赫尔河汇入。塔马尔河口流入普利茅斯湾，这是一个开阔的海湾，入口处有一个人工防波堤和西北方的德雷克岛。普利姆河流入普利茅斯湾的东北部。耶尔姆河口位于普利茅斯湾的东侧，潮汐范围达6.5公里。普利茅斯湾是一个重要的商业港口，德文波特皇家海军船坞位于塔马尔河口下游。该地区拥有悠久的海洋生物研究历史，既用于研究，也用于教育。自1884年以来，普利茅斯海洋生物协会的工作人员在该地区进行了研究。来自海洋环境研究学院的工作人员也在此进行研究，普利茅斯理工学院利用该地区进行学生项目和实习。普利茅斯湾的海岸线陡峭，几乎全部为岩石构成。其相关河口的沿岸地形一般较为平缓，并包含广阔的泥滩。岩石露头和陡峭的岩石斜坡也存在于一些河弯处。耶尔姆河口是一个狭窄而陡峭的河口，有一些分支。在水下，一条陡峭的河道蜿蜒穿过普利茅斯湾，从塔马尔河入口处开始，经过防波堤向外延伸。该河道深度可达40米。塔马尔是淡水输入的主要接受者，盐度通常在进入普利茅斯湾之前不会达到完全的海洋条件。普利茅斯湾的北部区域受到这种淡水输入的影响。普利姆和耶尔姆的淡水输入量较低。在塔马尔狭窄的岩石入口和德雷克岛与海湾西侧之间的“桥梁”处存在强潮流。海湾内部区域在入口处的防波堤得到庇护，但海湾外部，尤其是东侧，受到来自盛行西南风的强烈波浪作用。耶尔姆河口入口处由沙坝庇护。本次调查旨在收集有关海洋栖息地和社区的信息，这些信息和社区以前未曾被描述或自20世纪初以来未曾采样。记录了栖息在硬质表面和沉积物表面的物种丰度。通过0.01和0.1平方米的柱状样和挖掘收集了潮间带沉积物生物，并通过0.5毫米、1毫米和5毫米网孔的筛子进行筛选。使用管道吸扬式挖泥船在潮下带沉积物中取样，并在防波堤外使用吸扬式采样器。样品通过1毫米网孔的筛子进行筛选。从沉积物中挑选出动物，进行鉴定和计数。拍摄照片以说明栖息地、社区和物种。在4月的春分低潮期间，拍摄了一系列航空照片。将现有的栖息地和社区分类为29种潮间带类型（普利茅斯地区有22种，耶尔姆地区有7种）和28种潮下带类型（普利茅斯地区有22种，耶尔姆地区有6种）。对这些类型进行了描述，并在表格中显示了物种的丰度。讨论了栖息地的分布，并列出了潮下带底质类型。根据盐度、波浪暴露和其中发现的社区和物种，提出了塔马尔和普利茅斯湾的九个主要生态区，并进行了描述。这些区域被称为：开阔海域、开阔海岸、庇护海湾、外河口、下游河口、中游河口、上游河口、河-河口过渡区和河流区。将调查的栖息地和社区与其他海洋潟湖以及该地区的先前海洋生物研究进行了比较。普利茅斯湾和塔马尔地区的面积远大于大多数其他研究过的海洋潟湖，尽管它包括了众多相似的栖息地、社区和物种。耶尔姆虽小，但与其他潟湖相比表现优异。普利茅斯地区和耶尔姆河口的特征与1957年出版的《普利茅斯海洋动物志》以及本世纪上半叶（及19世纪后期）发表的研究成果大致相同。对于某些区域，我们的评估部分依赖于之前的工作。然而，本次调查发现了一些变化，并且首次对岩石底质栖息地上的社区进行了充分描述。还有一些物种是首次记录。这些包括红藻的物种、Schmitzia，以及包括Pisione remota、Ampharete lindstroemi和Protodorvillea kefersteini在内的多种多毛类环节动物。从防波堤北端也记录到了海葵 Virgularia mirabilis，此前未曾在此看到。在本次调查中，Apoglossum ruscifolium在哈莫泽地区被广泛记录，而约翰逊在1890年并未记录。Fucus vesiculosis在塔马尔河中的分布似乎自Percival（1929年）的记录以来向北扩展，而Cordylophora lacustris的分布似乎向下游扩展。前者表明淡水输入减少，而后者表明增加。在耶尔姆河口入口外的Kithching沟壑也注意到了一些细微的变化。该地区的科学价值和自然保护重要性已根据标准准则进行评估，该地区栖息地和社区的保育重要性已初步分级为地方、区域、国家或国际重要性。在调查期间确定的具有特殊科学兴趣的物种已记录，并对其保育重要性进行了初步分级为区域、国家或国际重要性。对于科学价值和自然保护重要性的总体评估，该地区被考虑为六个独立的部分：开阔海域和开阔海岸，以深海中发现的地中海-大西洋物种最为显著；外普利茅斯湾，有一些有趣的岩石海岸栖息地，尤其是岩石池塘，以及大片丰富而有趣的潮下带沉积物社区；内普利茅斯湾，有一些非常罕见的石灰岩基底社区，这些社区具有里亚特征，并有一些有趣的钻孔物种；卡特沃特和普利姆河口，有一些丰富的泥滩，但总体上重要性较低；塔马尔和林赫尔河口，以沿河口梯度延伸的岩石底质最为显著，以及下游丰富的水流冲刷的卵石和砾石；耶尔姆河口，由于栖息地和社区的多样性极高，几乎完全是自然形成的，因此具有突出的研究价值。普利茅斯湾及其相关河口的大部分地区受到人类活动的影响，但耶尔姆河口目前的休闲活动水平似乎并未损害其自然性，除了可能来自防污漆中有机锡的高水平。从本数据集中移除了目前认为敏感的记录。