Grattepanche Jean-David, Jeffrey Wade H, Gast Rebecca J, Sanders Robert W
Department of Biology, Temple University, Philadelphia, PA, United States.
Center for Environmental Diagnostics and Bioremediation, University of West Florida, Pensacola, FL, United States.
Front Microbiol. 2022 May 16;13:844856. doi: 10.3389/fmicb.2022.844856. eCollection 2022.
During a cruise from October to November 2019, along the West Antarctic Peninsula, between 64.32 and 68.37°S, we assessed the diversity and composition of the active microbial eukaryotic community within three size fractions: micro- (> 20 μm), nano- (20-5 μm), and pico-size fractions (5-0.2 μm). The communities and the environmental parameters displayed latitudinal gradients, and we observed a strong similarity in the microbial eukaryotic communities as well as the environmental parameters between the sub-surface and the deep chlorophyll maximum (DCM) depths. Chlorophyll concentrations were low, and the mixed layer was shallow for most of the 17 stations sampled. The richness of the microplankton was higher in Marguerite Bay (our southernmost stations), compared to more northern stations, while the diversity for the nano- and pico-plankton was relatively stable across latitude. The microplankton communities were dominated by autotrophs, mostly diatoms, while mixotrophs (phototrophs-consuming bacteria and kleptoplastidic ciliates, mostly alveolates, and cryptophytes) were the most abundant and active members of the nano- and picoplankton communities. While phototrophy was the dominant trophic mode, heterotrophy (mixotrophy, phagotrophy, and parasitism) tended to increase southward. The samples from Marguerite Bay showed a distinct community with a high diversity of nanoplankton predators, including spirotrich ciliates, and dinoflagellates, while cryptophytes were observed elsewhere. Some lineages were significantly related-either positively or negatively-to ice coverage (e.g., positive for Pelagophyceae, negative for Spirotrichea) and temperature (e.g., positive for Cryptophyceae, negative for Spirotrichea). This suggests that climate changes will have a strong impact on the microbial eukaryotic community.
2019年10月至11月，在南纬64.32度至68.37度之间的西南极半岛沿岸进行的一次巡航中，我们评估了三个粒径级分（微型（>20μm）、纳米级（20 - 5μm）和微微型（5 - 0.2μm））中活跃的微生物真核生物群落的多样性和组成。群落和环境参数呈现出纬度梯度，我们观察到亚表层和深层叶绿素最大值（DCM）深度之间的微生物真核生物群落以及环境参数具有很强的相似性。在17个采样站中的大多数站点，叶绿素浓度较低，混合层较浅。与更靠北的站点相比，玛格丽特湾（我们最南端的站点）的微型浮游生物丰富度更高，而纳米级和微微型浮游生物的多样性在纬度上相对稳定。微型浮游生物群落以自养生物为主，主要是硅藻，而兼养生物（消耗细菌的光合生物和盗食质体的纤毛虫，主要是肺泡虫和隐藻）是纳米级和微微型浮游生物群落中最丰富和活跃的成员。虽然光合营养是主要的营养模式，但异养（兼养、吞噬营养和寄生）有向南增加的趋势。来自玛格丽特湾的样本显示出一个独特的群落，有高度多样的纳米浮游生物捕食者，包括螺旋毛纲纤毛虫和甲藻，而隐藻在其他地方被观察到。一些谱系与冰覆盖（例如，对褐藻纲呈正相关，对螺旋毛纲呈负相关）和温度（例如，对隐藻纲呈正相关，对螺旋毛纲呈负相关）显著相关，无论是正相关还是负相关。这表明气候变化将对微生物真核生物群落产生强烈影响。
