Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Department of Marine Science, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
Sci Total Environ. 2019 Nov 25;693:133507. doi: 10.1016/j.scitotenv.2019.07.313. Epub 2019 Jul 20.
Systems with strong horizontal and vertical gradients, such as fjords, are useful models for studying environmental forcing. Here we examine microbial (prokaryotic and eukaryotic) community changes associated with the surface low salinity layer (LSL) and underlying seawater in multiple fjords in Fiordland National Park (New Zealand). High rainfall (1200-8000 mm annually) and linked runoff from native forested catchments results in surface LSLs with high tannin concentrations within each fjord. These gradients are expected to drive changes in microbial communities. We used amplicon sequencing (16S and 18S) to assess the impact of these gradients on microbial communities and identified depth linked changes in diversity and community structure. With increasing depth, we observed significant increases in Proteobacteria (15%) and SAR (37%), decreases in Opisthokonta (35%), and transiently increased Bacteroidetes (3% increase from 0 to 40 m, decreasing by 8% at 200 m). Community structure differences were observed along a transect from the head to the mouth, specifically 25% mean relative abundance decreases in Opisthokonta and Bacteroidetes, and increases in SAR (25%) and Proteobacteria (>5%) at the surface, indicating changes based on distance from the ocean. This provides the first in-depth view into the ecological drivers of microbial communities within New Zealand fjords.
具有强水平和垂直梯度的系统，如峡湾，是研究环境胁迫的有用模型。在这里，我们研究了多个峡湾中与表层低盐层 (LSL) 和底层海水相关的微生物（原核生物和真核生物）群落变化。高降雨量（每年 1200-8000 毫米）和来自原生森林集水区的相关径流导致每个峡湾的表层 LSL 中含有高浓度的单宁。这些梯度预计会导致微生物群落发生变化。我们使用扩增子测序（16S 和 18S）来评估这些梯度对微生物群落的影响，并确定了多样性和群落结构随深度的变化。随着深度的增加，我们观察到变形菌门（Proteobacteria）（15%）和酸杆菌门（SAR）（37%）显著增加，后生动物门（Opisthokonta）（35%）减少，而拟杆菌门（Bacteroidetes）暂时增加（从 0 到 40 米增加 3%，到 200 米减少 8%）。从峡湾头部到口部的横切线上观察到群落结构差异，特别是后生动物门和拟杆菌门的相对丰度分别减少 25%，而 SAR（25%）和变形菌门（Proteobacteria）（超过 5%）在表层增加，表明基于与海洋的距离而发生的变化。这首次深入了解了新西兰峡湾中微生物群落的生态驱动因素。
