Selective collection of iron-rich dust particles by natural Trichodesmium colonies

• Published in: The ISME Journal 2020-01, Vol.14 (1), p.91-103
• Main Authors: Kessler, Nivi, Armoza-Zvuloni, Rachel, Wang, Siyuan, Basu, Subhajit, Weber, Peter K., Stuart, Rhona K., Shaked, Yeala
• Format: Article
• Language: English
• Subjects: 14/28; 14/63; 631/326/171/1878; 631/326/47; 704/172; 704/47; BASIC BIOLOGICAL SCIENCES; Biogeochemistry; Biomedical and Life Sciences; Collection; Colonies; Constraints; Dissolution; Dust; Dust - analysis; Dust control; Ecology; ENVIRONMENTAL SCIENCES; Evolutionary Biology; GEOSCIENCES; Iron; Iron - analysis; Life Sciences; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Minerals; Nutrient cycles; Phytoplankton; Selectivity; Silica; Silicon dioxide; Translocation; Trichodesmium; Trichodesmium - chemistry; Water microbiology
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/s41396-019-0505-x

Dust is an important iron (Fe) source to the ocean, but its utilization by phytoplankton is constrained by rapid sinking and slow dissolution dust-bound iron (dust-Fe). Colonies of the globally important cyanobacterium, Trichodesmium , overcome these constraints by efficient dust capturing and active dust-Fe dissolution. In this study we examined the ability of Trichodesmium colonies to maximize their Fe supply from dust by selectively collecting Fe-rich particles. Testing for selectivity in particle collection, we supplied ~600 individual colonies, collected on multiple days from the Gulf of Aqaba, with natural dust and silica minerals that were either cleaned of or coated with Fe. Using a stereoscope, we counted the number of particles retained by each colony shortly after addition and following 24 h incubation with particles, and documented translocation of particles to the colony core. We observed a strong preference for Fe-rich particles over Fe-free particles in all tested parameters. Moreover, some colonies discarded the Fe-free particles they initially collected. The preferred collection of Fe-rich particles and disposal of Fe-free particles suggest that Trichodesmium can sense Fe and selectively choose Fe-rich dust particles. This ability assists Trichodesmium obtain Fe from dust and facilitate its growth and subsequent contribution to nutrient cycling and productivity in the ocean.