Abstract
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.
Highlights
Low Chlorophyll (LNLC) regions [1,2,3]
Our results suggest that surface-water Prochlorococcus biomass may be top-down regulated by viruses or other dust-borne biological agents such as extracellular vesicles associated with atmospheric aerosols either as free viruses/vesicles or within infected airborne Prochlorococcus cells, in addition to their role as sources of limiting nutrients (e.g., N, P and Fe) [11,29,45]
We show that airborne viruses or other biological agents such as extracellular vesicles may play a pivotal role in controlling the abundance and productivity of select cyanobacterial species
Summary
One of the major controls on the spatiotemporal distribution of cyanobacteria such as Prochlorococcus, especially in oligotrophic systems, is viral infection [4] and/or bacterial vesicles [5]. Another important constraint on Prochlorococcus biomass is nutrient bioavailability [9,10]. Several experimental and modelling studies demonstrated that the supply of nutrients and trace metals via atmospheric deposition may increase the biomass and carbon fixation rates of marine primary producers, including cyanobacteria, playing a significant role in the nutrition and ecology of LNLC regions [11,12]. Other studies reported specific reduction in Prochlorococcus activity/biomass following aerosol amendment in the tropical Northeast Atlantic Ocean, the Western Atlantic, the Pacific
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
