Presentation Information
[P04-571]Depth-dependent metabolomic responses of eelgrass (Zostera marina) to changes in light quality
○Yuji Takahashi1, Yu Umezawa1, Yoshimasa Todoroki1, Motohiro Ogawa1, Hiroshi Tsugawa1, Toru Hirawake2, Masakazu Hori3, Hiromori Shimabukuro3, Jun Hayakawa4 (1. Tokyo university of agriculture and technology (Japan), 2. National Institute of Polar Research (NIPR) (Japan), 3. Japan Fisheries Research and Education Agency (Japan), 4. Atmosphere and Ocean Research Institute The university of Tokyo (Japan))
Keywords:
seagrass meadow,metabolic analysis,depth environment,coastal ecosystem,Zostera marina
[Purpose]
Seagrass meadows contribute to carbon sequestration and biodiversity but have declined globally since the late 1900s, partly due to climate-related disturbances such as marine heatwaves. We therefore focused on deeper waters, where temperature increases and physical disturbances are relatively limited. This study aimed to identify physiological and environmental factors enabling eelgrass (Zostera marina) to grow at greater depths by comparing individuals and surrounding environments between shallow and deep waters.
[Method]
Eelgrass samples were collected in June 2024 and July 2025 at two coastal sites in Japan. Comparative analysis was conducted based on metabolite profiles of eelgrass from shallow and deep areas. Metabolite analysis was performed using LC-MS/MS, and annotated data were subjected to statistical analysis. Environmental conditions, including underwater light spectra, nutrient concentrations, and sediment grain size, were also measured. In addition, photosynthetic pigment contents (Chl a, Chl b, and total carotenoids: CARs) were quantified.
[Results]
Principal component analysis (PCA) of 36 metabolites clearly separated eelgrass individuals from shallow and deep sites along PC1. Loadings analysis revealed L-glutamic acid as a metabolite characterizing shallow areas, whereas orthophosphate and flavonoids were major contributors in deep areas. Chl a and b contents were significantly higher in deep-water individuals. While CARs showed site-dependent patterns, the ratio of total chlorophyll to carotenoids (Chl a+b/CARs) was higher in deep-water plants.
[Consideration]
Differences in metabolite composition and pigment content suggest that eelgrass in deep waters exhibits distinct physiological responses compared to shallow-water individuals. The increased chlorophyll content and higher Chl a+b/CARs ratio suggest a shift in resource allocation toward light-harvesting components under low-light conditions. The accumulation of flavonoids and inorganic phosphate may also reflect physiological adjustments associated with deep-water environments.
[Conclusion]
These results suggest that eelgrass in deep waters adopts physiological strategies that enhance light-harvesting capacity, which may contribute to its ability to persist under low-light conditions.
Seagrass meadows contribute to carbon sequestration and biodiversity but have declined globally since the late 1900s, partly due to climate-related disturbances such as marine heatwaves. We therefore focused on deeper waters, where temperature increases and physical disturbances are relatively limited. This study aimed to identify physiological and environmental factors enabling eelgrass (Zostera marina) to grow at greater depths by comparing individuals and surrounding environments between shallow and deep waters.
[Method]
Eelgrass samples were collected in June 2024 and July 2025 at two coastal sites in Japan. Comparative analysis was conducted based on metabolite profiles of eelgrass from shallow and deep areas. Metabolite analysis was performed using LC-MS/MS, and annotated data were subjected to statistical analysis. Environmental conditions, including underwater light spectra, nutrient concentrations, and sediment grain size, were also measured. In addition, photosynthetic pigment contents (Chl a, Chl b, and total carotenoids: CARs) were quantified.
[Results]
Principal component analysis (PCA) of 36 metabolites clearly separated eelgrass individuals from shallow and deep sites along PC1. Loadings analysis revealed L-glutamic acid as a metabolite characterizing shallow areas, whereas orthophosphate and flavonoids were major contributors in deep areas. Chl a and b contents were significantly higher in deep-water individuals. While CARs showed site-dependent patterns, the ratio of total chlorophyll to carotenoids (Chl a+b/CARs) was higher in deep-water plants.
[Consideration]
Differences in metabolite composition and pigment content suggest that eelgrass in deep waters exhibits distinct physiological responses compared to shallow-water individuals. The increased chlorophyll content and higher Chl a+b/CARs ratio suggest a shift in resource allocation toward light-harvesting components under low-light conditions. The accumulation of flavonoids and inorganic phosphate may also reflect physiological adjustments associated with deep-water environments.
[Conclusion]
These results suggest that eelgrass in deep waters adopts physiological strategies that enhance light-harvesting capacity, which may contribute to its ability to persist under low-light conditions.
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