Hypoxia is a major stressor on biological communities in many oceanic and coastal ecosystems. Various size-dependent processes (e.g. growth and reproduction rates, predator–prey interactions) are adversely affected by hypoxia. We hypothesized that the impacts of hypoxia on planktonic communities would also be reflected in their Normalized Biomass Size Spectra (NBSS) as steeper slopes and lower intercepts. To explore this hypothesis, we studied the planktonic communities (from bacteria to mesozooplankton) of Elefsina, an enclosed bay that exhibits near bottom hypoxia during summer, and Aghios Kosmas, an adjacent coastal site outside the bay. Bottom layer hypoxia formed during the stratification period in Elefsina Bay significantly altered the distribution of planktonic organisms in the water column. Several unicellular and mesozooplanktonic groups avoided the hypoxic layer, in which the biomass of autotrophic picoeukaryotes was markedly higher. Community changes related to hypoxia were clearly reflected in the NBSS. The slope was significantly steeper in the hypoxic layer (−1.330 vs −1.193) and the intercept was lower (−2.222 vs −0.972, hypoxic vs oxic layer). This result can be interpreted as reduced trophic transfer efficiency to the higher trophic levels due to hypoxia.

中文翻译：

---

低氧改变了浮游生物量生物量谱的形状：以地中海东部（Elefsina湾）为例

缺氧是许多海洋和沿海生态系统中生物群落的主要压力。各种取决于大小的过程（例如生长和繁殖率，食肉动物与猎物之间的相互作用）都受到缺氧的不利影响。我们假设低氧对浮游生物的影响也将在其归一化生物量大小谱（NBSS）中反映为更陡峭的坡度和更低的截距。为了探究这一假设，我们研究了Elefsina的浮游生物群落（从细菌到中层浮游生物），一个封闭的海湾在夏季在底部缺氧附近表现出封闭的海湾，而Aghios Kosmas则是该海湾以外的一个沿海站点。在Elefsina湾分层期间形成的底层缺氧显着改变了水柱中浮游生物的分布。几个单细胞和中膜lanktonic组避免缺氧层，其中自养微生核生物的生物量明显更高。与低氧有关的社区变化清楚地反映在NBSS中。低氧层的斜率明显较陡（-1.330对-1.193），截距较低（-2.222对-0.972，低氧对含氧层）。该结果可以解释为由于缺氧导致营养传递效率降低至较高的营养水平。