Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses

Seagrass beds provide critical ecosystem services, but seagrass growth can be hindered under high sulfide stress in often submerged ocean environments, particularly where nutrients are also limiting. Although symbiotic microbes associated with both bivalves and seagrass rhizospheres have been shown...

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Main Authors: Yizhou Sun, Yang Liu, Xing-Xing Cai, Mark D. Bertness, Qiang He
Format: Article
Language:English
Published: American Association for the Advancement of Science (AAAS) 2025-01-01
Series:Ecosystem Health and Sustainability
Online Access:https://spj.science.org/doi/10.34133/ehs.0389
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author Yizhou Sun
Yang Liu
Xing-Xing Cai
Mark D. Bertness
Qiang He
author_facet Yizhou Sun
Yang Liu
Xing-Xing Cai
Mark D. Bertness
Qiang He
author_sort Yizhou Sun
collection DOAJ
description Seagrass beds provide critical ecosystem services, but seagrass growth can be hindered under high sulfide stress in often submerged ocean environments, particularly where nutrients are also limiting. Although symbiotic microbes associated with both bivalves and seagrass rhizospheres have been shown to oxidize sulfides and transform nitrate to ammonia that could be used by seagrasses, their relative roles in facilitating seagrasses remain poorly understood. Here, we investigated the community structure and potential functions of bacteria associated with benthic clams and surface sediments in a seagrass bed and adjacent unvegetated mudflats. We found no significant differences in the community structure of clam gill bacteria between seagrass beds and mudflats, with Spirochetes being the predominant bacterial taxa, most of which did not have known functions related to sulfur metabolism and nutrient regulation. In contrast, there were significant differences in sediment bacterial communities between seagrass beds and mudflats. The relative abundances of Proteobacteria and Bacteroidota were significantly higher in seagrass rhizospheres than in mudflats, whereas Desulfobacterota and Chloroflexi were lower. Compared to mudflats, bacteria in seagrass rhizospheres were more closely associated with sulfide oxidation and nitrate reduction, but less with sulfate reduction. These results suggest that rhizosphere bacteria, rather than clam gill bacteria, may facilitate seagrasses by oxidizing sulfide and transforming nitrate to ammonia. The lack of sulfide-oxidizing symbionts in clam gills challenges perspectives from existing lucinidae bivalve studies and suggests a more prominent role of sediment microbes. Our findings provide new insights for understanding how seagrasses can thrive in high-sulfide, low-nutrient environments.
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institution Kabale University
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publishDate 2025-01-01
publisher American Association for the Advancement of Science (AAAS)
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spelling doaj-art-e4b099e5040e4c67aab1404984444de62025-08-20T03:56:14ZengAmerican Association for the Advancement of Science (AAAS)Ecosystem Health and Sustainability2332-88782025-01-011110.34133/ehs.0389Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate SeagrassesYizhou Sun0Yang Liu1Xing-Xing Cai2Mark D. Bertness3Qiang He4State Key Laboratory of Wetland Conservation and Restoration, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Shanghai 200438, China.State Key Laboratory of Wetland Conservation and Restoration, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Shanghai 200438, China.State Key Laboratory of Wetland Conservation and Restoration, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Shanghai 200438, China.Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, RI, USA.State Key Laboratory of Wetland Conservation and Restoration, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Fudan University, Shanghai 200438, China.Seagrass beds provide critical ecosystem services, but seagrass growth can be hindered under high sulfide stress in often submerged ocean environments, particularly where nutrients are also limiting. Although symbiotic microbes associated with both bivalves and seagrass rhizospheres have been shown to oxidize sulfides and transform nitrate to ammonia that could be used by seagrasses, their relative roles in facilitating seagrasses remain poorly understood. Here, we investigated the community structure and potential functions of bacteria associated with benthic clams and surface sediments in a seagrass bed and adjacent unvegetated mudflats. We found no significant differences in the community structure of clam gill bacteria between seagrass beds and mudflats, with Spirochetes being the predominant bacterial taxa, most of which did not have known functions related to sulfur metabolism and nutrient regulation. In contrast, there were significant differences in sediment bacterial communities between seagrass beds and mudflats. The relative abundances of Proteobacteria and Bacteroidota were significantly higher in seagrass rhizospheres than in mudflats, whereas Desulfobacterota and Chloroflexi were lower. Compared to mudflats, bacteria in seagrass rhizospheres were more closely associated with sulfide oxidation and nitrate reduction, but less with sulfate reduction. These results suggest that rhizosphere bacteria, rather than clam gill bacteria, may facilitate seagrasses by oxidizing sulfide and transforming nitrate to ammonia. The lack of sulfide-oxidizing symbionts in clam gills challenges perspectives from existing lucinidae bivalve studies and suggests a more prominent role of sediment microbes. Our findings provide new insights for understanding how seagrasses can thrive in high-sulfide, low-nutrient environments.https://spj.science.org/doi/10.34133/ehs.0389
spellingShingle Yizhou Sun
Yang Liu
Xing-Xing Cai
Mark D. Bertness
Qiang He
Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses
Ecosystem Health and Sustainability
title Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses
title_full Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses
title_fullStr Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses
title_full_unstemmed Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses
title_short Rhizosphere Bacteria, Rather Than Benthic Bivalve Symbionts, May Facilitate Seagrasses
title_sort rhizosphere bacteria rather than benthic bivalve symbionts may facilitate seagrasses
url https://spj.science.org/doi/10.34133/ehs.0389
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