Species point records from 1994 DWT Exmouth to Burton Bradstock (Lyme Bay) survey

The methodology followed that adopted by the regional National Rivers Authority (NRA) in their most recent surveys (National Rivers Authority, 1994a). Four replicates were taken at each site (although due to the smaller area of our corer, 3 closely spaced cores were used for each replicate). The surface area of each replicate was 0.01 square metre. Each core sample was taken to a depth of 15cm where possible (Photo 5b). Where stones prevented penetration to this depth the sample was taken as deep as possible and the actual depth noted. Samples were taken in the lower half of the shore (Mean Tidal Level to Mean Low Water Neap zone). The survey was carried out from 8-10 August 1994, during a period of spring tides. Most samples were taken within an hour of predicted low water; the only exception was Exmouth, where the samples were taken 1 hour 50 minutes before LW. The Ambios Health and Safety procedures were followed at all sites. Samples were carefully sieved through a 0.5mm mesh within 12 hours of sampling. All material retained by the sieve was preserved immediately in Industrial Methylated Spirits (IMS). No stain was added. All material retained by the sieve waas examined at a minumum of x7 magnification under a stereo zoom microscope. Specimens were identified to species level wherever possible (often using a compound microscope) and a reference collection for Lyme Bay was created. Difficult and unusual specimens were sent to independent specialists for confirmation or identification. These specialists were Dr Peter Garwood (polychaetes & crustaceans) Dennis Seaward (molluscs) and Dr Peter Kirby (groups usually encountered in terrestrial surveys.) The species list from this survey has been compared with other recent intertidal invertebrate data for Lyme Bay. This survey confirmed the high conservation value of the lower Exe estuary and Fleet Lagoon for marine invertebrates. Other sites had typical estuarine benthic communities, with a particularly good example near the mouth of the Otter estuary. Unusually impoverished benthic communities were present in the harbour sediments in West Bay and Lyme Regis. These results were probably due to pollution rather than natural causes. Considering that only 8 sites were surveyed, the number of taxa recorded (67) was unusually high for this estuarine/brackish intertidal soft sediment habitat. A very high propotion (42 out of 67) were found only at one site, often in very low numbers. The most unusual taxa recoreded were the polycheates Clymenura clypeata, Spio theeli, Armandia sp (possibly A.cirrhosa), and Syllis sp E (an undescribed species). The number of species recorded in the Fleet and Exe estuary increases with every specialist survey, reflecting the diverse nature of their invertebrate communities. Apart from mussel spat, the densities of the invertebrates were not exceptional when compared to results from other estuaries in the UK. Combined with data from surveys of the Teign, Exe, Otter and Axe by the National Rivers Authority, the data reported here provide a suitable quantative baseline for benthic invertebrates of sand and mud shores around Lyme Bay.

本研究所采用的方法论与区域国家河流管理局（NRA）在其最近一次调查中采用的方法一致（国家河流管理局，1994a）。在每个调查地点均进行了四次重复采样（尽管由于我们的岩心面积较小，每个重复采样使用了3个紧密排列的岩心）。每个重复采样的表面积为0.01平方米。在可能的情况下，每个岩心样本的采集深度为15厘米（见图5b）。在石块阻止穿透至该深度的情况下，样本的采集深度尽可能深，并记录实际深度。样本采集于岸线的下半部分（平均潮位至平均低潮不潮期）。调查于1994年8月8日至10日进行，期间为春潮期间。大多数样本在预测低潮前一小时采集；唯一的例外是Exmouth，样本采集在低潮前1小时50分钟。所有地点均遵循Ambios健康与安全程序。样本在采样后12小时内通过0.5毫米的网筛进行仔细筛选。所有通过网筛保留的物质立即用工业甲基化酒精（IMS）保存。未添加任何染色剂。所有通过网筛保留的物质均至少在立体显微镜下以x7倍放大倍数进行检查。尽可能将标本鉴定到物种水平（通常使用复合显微镜），并创建了莱姆湾的参考收藏。难以鉴定和罕见的标本被发送给独立专家进行确认或鉴定。这些专家包括彼得·加伍德博士（多毛类和甲壳类）、丹尼斯·肖沃德（软体动物）和彼得·柯比博士（通常在陆地调查中遇到的群体）。此次调查的物种列表已与其他最近莱姆湾潮间带无脊椎动物数据进行了比较。此次调查证实了下埃克斯河口和舰队潟湖对海洋无脊椎动物具有极高的保护价值。其他地点具有典型的河口底栖生物群落，其中奥特河口入口附近的一个例子尤为出色。在西湾和莱姆瑞斯的港口沉积物中存在异常贫瘠的底栖生物群落，这些结果可能是由于污染而非自然原因造成的。鉴于仅调查了8个地点，记录的物种数量（67个）对于这种河口/咸淡水潮间带软质沉积物生境来说是不寻常的高。其中高达42个（67个中的42个）仅在一个地点发现，通常数量非常少。记录的最不寻常的物种是环节动物Clymenura clypeata、Spio theeli、Armandia sp（可能是A.cirrhosa）和Syllis sp E（一种未描述的物种）。在舰队和埃克斯河口记录的物种数量随着每次专家调查的增加而增加，反映了其无脊椎动物群落的多样性。除了牡蛎幼虫外，与英国其他河口的结果相比，无脊椎动物的密度并不异常。结合国家河流管理局对泰恩河、埃克斯河、奥特河和阿克斯河的调查数据，本报告中的数据为莱姆湾周围沙质和泥质岸线的底栖无脊椎动物提供了合适的定量基准。