Habitat point records from 1982 Lumb Menai Strait sublittoral survey

This broad-scale survey was commissioned by the NCC to determine the range and distribution of sublittoral habitats and communities within the Menai Strait and adjacent areas. The survey complements other NCC funded studies of the rocky and soft sediment shores of the Menai Strait also carried out in 1982 and follows a long history of scientific investigation in the Strait. The central region of the Menai Strait is between 250 m and 500 m wide and 3 m to 25 m deep. The seabed consists of rocky shoals with areas of stones and gravel. To the north-east the Strait widens and extensive areas of mud and sand flats occur. To the south-west there are large areas of sand banks and where the low water channel is narrow the bottom is scoured and stony. Sediment predominates on the west coast of Anglesey, and on the east coast extensive rocky substrata are present. Wave action is generally reduced within the Strait, but tidal velocities reach 8 knots in the central area, although the current is sufficiently low in other regions to allow deposition of silt. Transects were selected at 1 km intervals along the Strait for dive sites, and site profiles recorded outside the Strait. Habitats were described, algal and animal communities recorded and photographs of the range of habitat types, communities and species observed taken. A total of 40 sites were surveyed and the distribution of major habitats and communities in the survey area mapped using survey results and other published and unpublished information. The report gives full descriptions of communities present in all habitat types identified and their extent and provides notes on the distribution and habitat preferences of each species. Biogeographical discontinuities within the survey area are identified and attributed to the influence of a range of environmental factors including wave action, water quality, the distribution of rocky substrata and geology. Some typical west coast species are identified and other species found to be common on the east coast but uncommon or rare on the west coast survey area. The diversity and richness of habitats and communities in the survey area is described. Only a limited range of habitats were present at the west coast sites surveyed, this part of the survey area being atypical of the west coast of Anglesey as a whole due to the increased turbidity conditions. Greater diversity is found further to the north-west of the survey area on this coast. The east coast sites showed a considerable diversity of habitats due to the broken limestone substratum and the variation in exposure to tidal streams in the vicinity of Puffin Island. The varied local topography and geology of the Menai Strait produced a series of habitats ranging in tidal stream exposure from very exposed to sheltered. The faunal communities recorded and the habitats in which they were observed could be distinctly identified, each often dominating areas of seabed although ultimately forming part of a continuum. As a tidal rapid, the habitats present in the central region of the Menai Strait are relatively unique. Although there are a number of tidal rapids on the west coast of Scotland, these are generally shallow and kelp-dominated. (The depth distribution of algae in the survey area is very restricted by the turbidity of the water and the communities present are therefore animal-dominated). The only site in the British Isles identified as having great similarity with the Menai Strait is Strangford Lough on the eastern Irish Sea coast, another example of a deep-water tidal rapids. The scientific interest and conservation value of the survey area is assessed in the report using the NCR criteria with modifications as stated in the NCC/NERC report - Nature Conservation in the Marine Environment, 1979. The survey report concludes that the designation of the central region of the Menai Strait, on its own or as part of a marine reserve encompassing the whole of the Menai Strait, would allow the conservation and maintenance of a unique ecosystem, as well as promoting survey and research programmes into the area and enhancing its educational and amenity value.

本项大规模调查由NCC委托进行，旨在确定曼恩海峡及其邻近海域海底栖息地和群落的空间分布与范围。该调查是对1982年NCC资助的曼恩海峡岩石和软质沉积岸线研究的重要补充，并延续了该海峡长期以来的科学探究历史。曼恩海峡中部区域宽度介于250米至500米之间，深度为3米至25米。海底由岩石浅滩组成，分布有石块和砾石。向东北方向，海峡变宽，出现大面积的泥质和沙滩。向西南方向，则是广阔的沙滩地带，在低潮水道狭窄处，底部被冲刷成石质。安格尔西岛的西海岸以沉积物为主，而东海岸则广泛分布着岩石基底。海峡内波浪作用一般较弱，但中心区域的潮流速度可达8节，尽管在其他区域水流速度足够低，足以使泥沙沉积。在海峡沿线每隔1公里选择横断面作为潜水点，并在海峡外部记录了地点剖面。对栖息地进行描述，记录了藻类和动物群落，并拍摄了各类栖息地类型、群落和物种的分布照片。共调查了40个地点，并使用调查结果以及其他已发表和未发表的信息，绘制了调查区域内主要栖息地和群落的分布图。报告对所识别的所有栖息地类型中的群落进行了详细描述，并提供了每个物种的分布和栖息地偏好的注释。在调查区域内识别了生物地理学上的不连续性，并将其归因于多种环境因素的影响，包括波浪作用、水质、岩石基底的分布和地质条件。确定了典型的西海岸物种，并发现其他物种在东海岸较为普遍，但在西海岸调查区域内则较为罕见或稀有。描述了调查区域内栖息地和群落的多样性和丰富性。在调查的西海岸地点，仅存在有限范围的栖息地，这部分调查区域由于浊度条件的增加，与安格尔西岛的整体西海岸不典型。在调查区域的西北方向发现了更大的多样性。东海岸地点由于破碎的石灰岩基底以及附近普夫林岛潮汐流的暴露程度不同，表现出显著的栖息地多样性。曼恩海峡错综复杂的局部地形和地质条件产生了从非常暴露到隐蔽的一系列栖息地。记录的动物群落及其观察到的栖息地可以明确区分，每个群落通常占据海底的特定区域，尽管最终它们构成了一个连续体。作为潮汐急流，曼恩海峡中心区域的栖息地相对独特。尽管苏格兰西海岸有多个潮汐急流，但这些一般较浅，以海藻为主。（调查区域藻类的深度分布受到水质浊度的严格限制，因此群落以动物为主）。在大不列颠群岛中，唯一被认定为与曼恩海峡具有高度相似性的地点是爱尔兰海东海岸的斯特兰福德湖，这是另一个深水潮汐急流的例子。报告使用NCR标准，并根据NCC/NERC报告《海洋环境中的自然保护》（1979年）中所述的修改，对调查区域的科学价值和保护价值进行了评估。调查报告得出结论，将曼恩海峡中部区域指定为保护区，或作为包含整个曼恩海峡的海洋保护区的一部分，将有利于独特生态系统的保护和维护，同时促进该区域的调查和研究项目，并提升其教育和休闲价值。