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| Main Authors: | , , |
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| Format: | Artículo científico |
| Language: | en |
| Published: |
Marine pollution bulletin
2024
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| Subjects: | |
| Online Access: | https://pubmed.ncbi.nlm.nih.gov/39418874/ |
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Table of Contents:
- Anoxic seagrass leaf environments as potential hotspots for toxin production and NO emission. Zhang, Qingfeng Kühl, Michael Brodersen, Kasper Elgetti Plant Leaves Nitrous Oxide Zosteraceae Biofilms Bacteria Marine Toxins Seawater Hydrogen Sulfide Oxygen Nitric Oxide Epiphytes on seagrass leaves can render parts of the leaf phyllosphere anoxic in darkness owing to leaf/epiphyte respiration and O diffusion constraints. In such anoxic microenvironments, anaerobic microbes can potentially produce phytotoxins and greenhouse gases, but the actual occurrence of such processes in seagrass epiphytic biofilms remain uncertain. We used microsensors to measure O, NO, NO and HS concentration gradients, as well as NO and O dynamics within epiphytic biofilms on seagrass (Zostera marina) leaves under changing environmental conditions. The bacterial community composition of epiphytic biofilms was analyzed with 16S rRNA gene amplicon sequencing. Flavobacteriaceae and Rhodobacteraceae were dominant bacterial community members accounting for ˃50 % of the relative abundance, and sulfate-reducing bacteria (Desulfobacterota) were omnipresent in the epiphytic biofilms. We found pronounced production of NO, NO and HS in anoxic parts of the seagrass phyllosphere, with NO and HS reaching maximal concentrations of 1.0 and 4.4 μmol L, respectively, under slow flow and hypoxic seawater conditions, while the highest NO concentration in the epiphytic biofilms reached 5.9 μmol L in hypoxic, nitrate-rich seawater. Part of the phytotoxic NO and HS diffused into the seagrass leaves, while no NO escaped the biofilm. In contrast, NO emission from the biofilm in hypoxic and eutrophic seawater reached 9.6 μmol NO m day. Such release of the potent greenhouse gas NO from seagrass leaves with epiphytic biofilms under eutrophic conditions could potentially offset the carbon burial capacity of seagrass meadows. Ocean eutrophication can thus stimulate denitrification and sulfate reduction within anoxic leaf microenvironments, negatively impacting seagrass fitness and ecological function.