Hosia Aino, Falkenhaug Tone, Baxter Emily J, Pagès Francesc
Department of Natural History, University Museum of Bergen, University of Bergen, Bergen, Norway.
Institute of Marine Research, Flødevigen, Norway.
PLoS One. 2017 Nov 2;12(11):e0187491. doi: 10.1371/journal.pone.0187491. eCollection 2017.
The diversity and distribution of gelatinous zooplankton were investigated along the northern Mid-Atlantic Ridge (MAR) from June to August 2004.Here, we present results from macrozooplankton trawl sampling, as well as comparisons made between five different methodologies that were employed during the MAR-ECO survey. In total, 16 species of hydromedusae, 31 species of siphonophores and four species of scyphozoans were identified to species level from macrozooplankton trawl samples. Additional taxa were identified to higher taxonomic levels and a single ctenophore genus was observed. Samples were collected at 17 stations along the MAR between the Azores and Iceland. A divergence in the species assemblages was observed at the southern limit of the Subpolar Frontal Zone. The catch composition of gelatinous zooplankton is compared between different sampling methodologies including: a macrozooplankton trawl; a Multinet; a ringnet attached to bottom trawl; and optical platforms (Underwater Video Profiler (UVP) & Remotely Operated Vehicle (ROV)). Different sampling methodologies are shown to exhibit selectivity towards different groups of gelatinous zooplankton. Only ~21% of taxa caught during the survey were caught by both the macrozooplankton trawl and the Multinet when deployed at the same station. The estimates of gelatinous zooplankton abundance calculated using these two gear types also varied widely (1.4 ± 0.9 individuals 1000 m-3 estimated by the macrozooplankton trawl vs. 468.3 ± 315.4 individuals 1000 m-3 estimated by the Multinet (mean ± s.d.) when used at the same stations (n = 6). While it appears that traditional net sampling can generate useful data on pelagic cnidarians, comparisons with results from the optical platforms suggest that ctenophore diversity and abundance are consistently underestimated, particularly when net sampling is conducted in combination with formalin fixation. The results emphasise the importance of considering sampling methodology both when planning surveys, as well as when interpreting existing data.
2004年6月至8月，对大西洋中脊北部的凝胶状浮游动物的多样性和分布进行了调查。在此，我们展示了大型浮游动物拖网采样的结果，以及在MAR-ECO调查期间采用的五种不同方法之间的比较。从大型浮游动物拖网样本中总共鉴定出16种水螅水母、31种管水母和4种钵水母至物种水平。其他分类群被鉴定到更高的分类水平，并观察到一个栉水母属。沿着亚速尔群岛和冰岛之间的大西洋中脊在17个站点采集了样本。在亚极地锋区的南界观察到物种组合的差异。比较了不同采样方法下凝胶状浮游动物的渔获组成，包括：大型浮游动物拖网；多网；附着在底拖网上的环形网；以及光学平台（水下视频剖面仪（UVP）和遥控水下机器人（ROV））。结果表明，不同的采样方法对不同种类的凝胶状浮游动物具有选择性。在同一站点部署时，调查期间捕获的分类群中只有约21%同时被大型浮游动物拖网和多网捕获。使用这两种渔具类型计算的凝胶状浮游动物丰度估计值也有很大差异（在同一站点使用时，大型浮游动物拖网估计为1.4±0.9个个体/1000立方米，而多网估计为468.3±315.4个个体/1000立方米（平均值±标准差），n = 6）。虽然传统的网采样似乎可以生成有关远洋刺胞动物的有用数据，但与光学平台的结果比较表明，栉水母的多样性和丰度一直被低估，特别是当网采样与福尔马林固定结合进行时。结果强调了在规划调查以及解释现有数据时考虑采样方法的重要性。
