Species point records from 1988 MNCR Rockall survey

Rockall and its associated reefs are situated 306 km west of St Kilda on the Rockall Plateau, and are isolated from the shallow waters around Britain by the Rockall Trough, which reaches depths of over 3000 m. Marine biologically they are of particular interest as the marine communities are at the extreme wave exposed end of our currently perceived wave exposure scales, and their isolation prevents an effective barrier for colonisation by organisms with pelagic larvae. This survey was carried out in June 1988, in unusually calm weather. The survey team was based aboard the Department of Agriculture and Fisheries for Scotland's Fishery Protection Vessel 'Norna'. Two littoral sites were surveyed on Rockall, and ten sublittoral sites on Rockall and the associated reefs. Previous studies on the marine biology of Rockall have suggested that its small size, isolation and extreme wave exposure have reduced the diversity of the littoral and sublittoral species present. The results of this survey suggest that this view still holds true and that the general impoverishment reflects the isolation and general wave exposure of the site. However, in the littoral, rock crevices and hollows under the encrusting red algae were found to harbour more animal species than the rock surfaces previously surveyed. Although it is generally the case that animals recorded from the littoral of Rockall do not have a pelagic dispersal phase, a small group of the barnacle Verruca stroemia were recorded on the rock, and the molluscs Hiatella and Modiolus within the algal crusts during this survey, indicating that settlement from a planktonic dispersal phase must be possible. The sublittoral of Rockall was richer than previously reported, although many algal species present at St Kilda were not recorded. Of the species recorded, some were found much deeper than expected, such as the brown alga Alaria esculenta which extended down to 33 m. The kelps Laminaria digitata and L.hyperborea were absent from Rockall and Hasselwood Rock, although they were recorded from Helen's Reef. This may be due to the greater availability of upward facing rock surfaces on Helen's Reef, which present an easier surface for colonisation than the predominantly vertical surfaces recorded around Rockall. This synopsis has been extracted from the field report. The final survey report has not yet been produced.罗卡尔岛（Rockall）及其附属礁石坐落于圣基尔达（St Kilda）以西306公里的罗卡尔海台（Rockall Plateau），被深度逾3000米的罗卡尔海槽（Rockall Trough）与英国周边浅海水域相互隔绝。从海洋生物学角度而言，该区域具有特殊研究价值：其海洋生物群落处于当前已知的波浪冲击强度最高区间，且极度孤立的地理位置形成了有效屏障，阻碍了携带浮游幼体的生物在此完成定植。本次调查于1988年6月在异常平缓的海况下开展，调查团队依托苏格兰农业与渔业部的渔业保护船‘诺纳号’（'Norna'）执行作业。调查共覆盖罗卡尔岛的2个潮间带（littoral）站点，以及罗卡尔岛及其附属礁石的10个潮下带（sublittoral）站点。此前针对罗卡尔岛海洋生物学的研究指出，其面积狭小、地理位置孤立且受极端波浪冲击，导致当地潮间带与潮下带的物种多样性显著降低。本次调查结果进一步印证了这一结论，即该海域的物种普遍匮乏现象，正是由其孤立性与高强度波浪暴露环境共同造成的。不过在潮间带区域，研究团队发现附着性红藻下方的岩石缝隙与凹陷处，栖息的动物物种数量多于此前调查过的岩石表面。尽管通常认为罗卡尔岛潮间带记录到的动物均不具备浮游扩散阶段，但本次调查在岩石上发现了少量疣纹藤壶（Verruca stroemia），并在藻层下方发现了海笋属（Hiatella）与偏顶蛤属（Modiolus）软体动物，这表明通过浮游扩散阶段完成定植具备可行性。罗卡尔岛的潮下带物种丰富度高于此前报道的结果，尽管圣基尔达海域存在的多种藻类未在本次调查中被记录。在所记录的物种中，部分物种的分布深度远超预期，例如可食翅藻（Alaria esculenta）的分布深度可达33米。掌状海带（Laminaria digitata）与极北海带（Laminaria hyperborea）未在罗卡尔岛与哈塞尔伍德礁（Hasselwood Rock）被发现，但在海伦礁（Helen's Reef）有相关记录。这一差异可能源于海伦礁拥有更多朝上的岩石表面，相较于罗卡尔周边以垂直面为主的生境，更利于生物完成定植。本摘要源自野外调查报告，最终的正式调查报告尚未编制完成。