Species point records from 1987 OPRU HRE Portland and Weymouth Harbours survey

Portland and Weymouth harbours are situated on the south coast of Dorset to the north of the isle of Portland (or Portland Bill). Portland harbour encloses a large area of seabed and is sheltered in all weather by the Portland peninsula and Chesil beach to the south and west and a series of breakwaters to the east. The entrance to the Fleet lagoon lies within the harbour on the north-west side. The bottom of the harbour is 10 to 17m below chart datum over most of its area, but slopes gradually up to intertidal sediments on the west side. Temperatures in Portland harbour become significantly elevated during the summer and freshwater input is minimal. Muddy sediments cover most of the bottom, but the artificial breakwaters are formed of limestone block tumbles with abundant crevices and interstices. Rocky outcrops, boulders, cobbles and pebbles on the bottom of Portland harbour increase the habitat diversity. Weymouth harbour is small and narrow and lies at the mouth of the River Wey, less than 1km north of Portland Harbour, with a north-east facing entrance. It is dredged to 5 to 7m and has no intertidal areas except for vertical walls. Freshwater inputs are also small and the water is, for the most part, fully marine. The breakwater is made of concrete walls and pilings, and there is little other hard substrata. The bottom is covered in muddy sediments. Portland harbour is a navel base and a certain amount of research and other Navel operations are carried out within designated areas. Commercial operations are few, but the fish quay at Castletown pier is thriving ahd there are some small fish-farming operations. There are recent proposals to increase the scale of salmon farming in the harbour. The harbour is popular for water sports, particulary sailboarders, and there are some small boat yards and sailing clubs. It is also a popular diving site. While most marine biological studies have concentrated on the Fleet lagoon, there is a long history of specimen collecting and other studies in the harbour. The Fleet study group have surveyed stations in the harbour and have compiled records of species found there. Weymouth harbour is more commercially orientated with a cross-channel ferry port and a Ro-Ro terminal. It is also used by commercial and sports fishermen and there are a large number of moorings in the Backwater. There are a number of wharves and three boatyards. There have been no known previous marine biological studies in Weymouth harbour. Twelve diving sites were surveyed during this survey, nine from within Portland harbour, one outside the harbour and two in the entrance to Weymouth harbour. In addition, grab samples of subtidal sediments from four sites in Portland harbour, sampled by Wessex Water Authority, werte analysed and the results are included in this report. Sixteen subtidal habitats and associated communities have been described from these sites. Descriptions are given of these and lists of species found are tabulated. The findings of other workers are incorporated into the discussion and conservation assessment. The conditions of sheltered, warm, clear, fully marine water in Portland harbour are unique to Britain and have allowed a large number of warm water species to live there. These include the Black-faced blenny Tripterygion atlanticus, the Red-band fish Cepola rubescens, the burrowing anemone Scolanthus callimorphus, the nudibranch mollusc Aeolidiella alderi and the polycheate worm Sternapsis scutata. The habitats and communities in the harbour are otherwise similar to those found in other inlets, but the bottom sediments contain very rich communities of infaunal animals, there are interesting communities of sessile fauna and flora on the vertical sides of the limestone blocks of the breakwater and the subtidal communities in the entrance to the Fleet are also fairly rich. The mudstone platform habitat surveyed outside the harbour was colonised with diverse assemblages of sponges, hydroids and ascidians which are similar to those recorded by the Dorset Underwater Survey. The communities recorded in the entrance to Weymouth Harbour included some fairly rich algal communities in shallow water on the pier piles, but the muddy sediments were poorly colonised. The scientific interest and conservation importance of the area has been assessed using standard criteria and the conservation importance of habitats and communities in the area have been provisionally graded as of Local, Regional or International importance. Species of particular scientific interest have been tabulated and there conservation importance provisionally graded as of Regional or National importance. Portland harbour is considered to be of high scientific and conservation importance. Overall diversity of species is high and there are a large number of species of conservation interest. Weymouth harbour is not considered to be of any conservation importance. Records currently considered sensitive have been removed from this dataset.

波特兰港和韦茅斯港位于多塞特郡南部海岸，座落于波特兰岛（或波特兰比尔）的北侧。波特兰港环绕着广阔的海床区域，四周均由波特兰半岛和切塞尔海滩（位于南西两侧）以及一系列防波堤（位于东侧）所庇护。舰队潟湖的入口位于港内的西北侧。港口底部在大部分区域的海图基准面下10至17米，但向西侧的潮间沉积物逐渐倾斜。夏季期间，波特兰港的温度显著升高，淡水的输入量极低。淤泥沉积物覆盖了大部分底部，而人工防波堤由石灰岩块堆积而成，其表面布满裂缝和间隙。波特兰港底部的岩石露头、巨石、鹅卵石和砾石增加了栖息地的多样性。韦茅斯港较小且狭窄，位于韦河河口，距离波特兰港不足1公里，入口朝向东北。港口经过疏浚，深度为5至7米，除垂直墙壁外，没有潮间区域。淡水的输入量也很小，大部分水域均为全海水。防波堤由混凝土墙壁和桩组成，几乎没有其他硬质底质。底部覆盖着淤泥沉积物。波特兰港是一个海军基地，在指定区域内进行了一定数量的研究和其他海军活动。商业活动较少，但卡斯尔敦码头上的鱼市繁荣，还有一些小型水产养殖活动。最近有提议增加港内的鲑鱼养殖规模。该港口因水上运动而闻名，尤其是帆板运动，还有一些小型船坞和帆船俱乐部。它也是一个受欢迎的潜水地点。尽管大多数海洋生物学研究都集中在舰队潟湖，但该港在标本收集和其他研究方面有着悠久的历史。舰队研究小组已对港口内的站点进行了调查，并编制了发现的物种记录。韦茅斯港更具商业导向，设有跨海峡渡轮港口和滚装码头。它也被商业和体育渔民使用，在背水区域有大量系船设施。该区域有多个码头和三个船坞。在此之前，韦茅斯港尚未进行过已知的海洋生物学研究。在本次调查中，对十二个潜水地点进行了调查，其中九个位于波特兰港内，一个位于港外，两个位于韦茅斯港的入口处。此外，来自波特兰港四个地点的潮下沉积物抓取样本（由韦塞克斯水务局采集）被分析，并包含在本报告中。从这些地点描述了十六种潮下生境及其相关群落。对这些生境和物种列表进行了描述。其他研究者的发现被纳入讨论和保育评估中。该区域的科学兴趣和保育重要性已使用标准标准进行评估，该区域生境和群落的保育重要性初步分级为地方、区域或国际重要性。具有特定科学兴趣的物种已列出，其保育重要性初步分级为区域或国家重要性。波特兰港被认为具有极高的科学和保育重要性。物种总体多样性较高，有许多具有保育价值的物种。韦茅斯港被认为不具备任何保育重要性。目前认为敏感的记录已从本数据集中删除。