Laboratoire d'Océanologie et Géoscience (LOG), UMR CNRS 8187, Université du Littoral Côte d'Opale, Université Lille Nord, Wimereux, France.
PLoS One. 2012;7(6):e39924. doi: 10.1371/journal.pone.0039924. Epub 2012 Jun 29.
Massive phytoplankton blooms, like the recurrent Phaeocystis proliferation observed every year in the Eastern English Channel (EEC), have a significant influence on the overall planktonic community structure and their food web dynamics. As well as being an important area for local fisheries, the EEC is an ideal ecosystem for work on microbial diversity. This is because, although its environmental context is relatively complex, it is reasonably well understood due to several years of monitoring and morphological observations of its planktonic organisms. The objective of our study was to better understand the under-explored microbial eukaryotic diversity relative to the Phaeocystis bloom.
The community structure of microplankton (diatoms, haptophytes, ciliates and dinoflagellates) was studied through morphological observations and tag pyrosequencing. During the annual Phaeocystis spring bloom, the phytoplankton biomass increased by 34-fold, while the microzooplankton biomass showed a 4-fold increase, representing on average about 4.6% of the biomass of their phytoplankton prey. Tag pyrosequencing unveiled an extensive diversity of Gymnodiniaceae, with G. spirale and G. fusiformis representing the most abundant reads. An extended diversity of Phaeocystales, with partial 18S rDNA genes sequence identity as low as 85% was found, with taxa corresponding to P. globosa, but also to unknown Phaeocystaceae.
Morphological analyses and pyrosequencing were generally in accordance with capturing frequency shifts of abundant taxa. Tag pyrosequencing allowed highlighting the maintenance of microplankton diversity during the Phaeocystis bloom and the increase of the taxa presenting low number of reads (minor taxa) along with the dominant ones in response to biotic and/or abiotic changing conditions. Although molecular approaches have enhanced our perception on diversity, it has come to light that the challenge of modelling and predicting ecological change requires the use of different complementary approaches, to link taxonomic data with the functional roles of microbes in biogeochemical cycles.
大规模的浮游植物水华，如每年在东英吉利海峡（EEC）反复出现的聚球藻增殖，对浮游群落结构及其食物网动态有重大影响。EEC 不仅是当地渔业的重要区域，也是微生物多样性研究的理想生态系统。这是因为，尽管其环境背景相对复杂，但由于多年来对其浮游生物的监测和形态观察，其环境背景已得到较好的理解。我们研究的目的是更好地了解相对于聚球藻水华的微生物真核生物多样性。
通过形态观察和标签焦磷酸测序研究了微浮游生物（硅藻、甲藻、纤毛虫和鞭毛藻）的群落结构。在每年的聚球藻春季水华期间，浮游植物生物量增加了 34 倍，而微型浮游动物生物量增加了 4 倍，平均占其浮游植物猎物生物量的 4.6%左右。标签焦磷酸测序揭示了旋沟藻科的广泛多样性，其中螺旋沟藻和梭形沟藻代表最丰富的读取序列。发现了扩展的聚球藻目多样性，部分 18S rDNA 基因序列同一性低至 85%，包括与聚球藻属相对应的分类单元，但也有未知的聚球藻科。
形态分析和焦磷酸测序通常与捕获丰富类群的频率变化一致。标签焦磷酸测序允许在聚球藻水华期间突出维持微浮游生物多样性，并在生物和/或非生物变化条件下，随着主要类群的增加，增加具有低读取数（次要类群）的类群。尽管分子方法增强了我们对多样性的认识，但事实证明，要对生态变化进行建模和预测，需要使用不同的互补方法，将分类数据与微生物在生物地球化学循环中的功能作用联系起来。
