The marine cyanobacterium Prochlorococcus is a dominant photoautotroph in many oligotrophic Low-Nutrients-Low-Chlorophyll (LNLC) regions. While the chemical impact of aerosols upon interaction with surface seawater was documented in numerous studies, we show that Prochlorococcus cells are affected also by bio-aerosols (potentially biological agents in the dust/aerosols such as membrane-bound extracellular vesicles, small-size bacteria and/or viruses), resulting in lower surface seawater abundances in the oligotrophic Mediterranean Sea. We conducted experimental amendments of ‘live’ aerosol/dust particles and aerosol filtrates (<0.22-µm) to surface Southeastern Mediterranean seawater or to pure Prochlorococcus cultures (MED4). Results show a significant decline in cell biomass (<90%), while UV-sterilized aerosols elicited a much weaker and non-significant response (~10%). We suggest that the difference is due to a negative effect of bio-aerosols specific to Prochlorococcus. Accordingly, the dominance of Synechococcus over Prochlorococcus throughout the surface Mediterranean Sea (observed mainly in spring when atmospheric aerosol levels are relatively high) and the lack of spatial westward gradient in Prochlorococcus biomass as typically observed for chlorophyll-a or other cyanobacteria may be attributed, at least to some extent, to the impact of bio-aerosol deposition across the basin. Predictions for enhanced desertification and increased dust emissions may intensify the transport and potential impact of bio-aerosols in LNLC marine systems.

中文翻译：

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生物气溶胶对富营养化气溶胶丰富的海洋地区的原球菌产生负面影响

海洋蓝细菌Prochlorococcus是许多低营养的低营养素-低叶绿素（LNLC）地区的主要自养生物。虽然在许多研究中都记录了气溶胶对与地表海水相互作用的化学影响，但我们显示原球菌还受到生物气溶胶（灰尘/气溶胶中的潜在生物因子，如膜结合的细胞外囊泡，小型细菌）的影响。和/或病毒），导致贫营养地中海地区的海水表层海水含量较低。我们对“活性”气溶胶/粉尘颗粒和气溶胶滤液（<0.22 µm）进行了实验性修正，以适应地中海东南部的海水或纯净的Prochlorococcus文化（MED4）。结果表明，细胞生物量显着下降（<90％），而紫外线消毒的气雾剂引起的响应则弱得多且不显着（〜10％）。我们认为，差异是由于特定于Prochlorococcus的生物气溶胶的负面影响所致。因此，在整个地中海表层海域中，球菌在Prochlorococcus上的优势（主要在春季，当大气气溶胶水平相对较高时观察到），而Prochlorococcus生物量缺乏空间向西的梯度（通常在叶绿素a中观察到）或其他蓝细菌可能至少在某种程度上归因于整个盆地内生物气溶胶沉积的影响。加强荒漠化和增加粉尘排放的预测可能会加剧LNLC海洋系统中生物气溶胶的运输和潜在影响。