Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea
Abstract Stratification is a fundamental process influencing nutrient availability and biological productivity in coastal marine ecosystems. In this study, we examine multi-decadal variability in winter stratification and nutrient distribution within Western margin of the East Sea (WES), using obser...
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Nature Portfolio
2025-08-01
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| Series: | Scientific Reports |
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| Online Access: | https://doi.org/10.1038/s41598-025-16226-8 |
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| author | Hae Kun Jung Changsin Kim Beom Sik Kim Jeong Hee Shim In Seong Han Chung Il Lee Dongyoung Kim |
| author_facet | Hae Kun Jung Changsin Kim Beom Sik Kim Jeong Hee Shim In Seong Han Chung Il Lee Dongyoung Kim |
| author_sort | Hae Kun Jung |
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| description | Abstract Stratification is a fundamental process influencing nutrient availability and biological productivity in coastal marine ecosystems. In this study, we examine multi-decadal variability in winter stratification and nutrient distribution within Western margin of the East Sea (WES), using observational data collected between 1990 and 2023. Stratification characteristics were quantified using the Brunt-Väisälä frequency (N²), with particular focus on changes in intensity and the depth of maximum stratification. These variables were then analyzed in relation to environmental factors such as upper-layer temperature, surface wind speed, and East Korea Warm Current (EKWC) transport. Over the study period, stratification intensity increased at an average rate of 1.1% per year, while the maximum stratification depth shoaled by approximately 0.6% annual trends that became more pronounced after 2015. These shifts were closely linked to enhanced thermal stratification and increased EKWC volume transport. Enhanced stability of the water column was accompanied by reduced vertical mixing, which in turn intensified the nitrate gradient between surface and subsurface waters. The most marked nitrate accumulation was observed near 100 m, where stratification was strongest. This study highlights how physical oceanographic changes during winter can regulate nutrient supply prior to the spring bloom, potentially influencing seasonal productivity in marginal seas. The results emphasize the importance of long-term monitoring of vertical structure in assessing the ecological impacts of ocean variability. |
| format | Article |
| id | doaj-art-6c923a3efebc4b94b2dfb09dcb9a6959 |
| institution | Kabale University |
| issn | 2045-2322 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Nature Portfolio |
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| series | Scientific Reports |
| spelling | doaj-art-6c923a3efebc4b94b2dfb09dcb9a69592025-08-24T11:30:03ZengNature PortfolioScientific Reports2045-23222025-08-0115111510.1038/s41598-025-16226-8Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East seaHae Kun Jung0Changsin Kim1Beom Sik Kim2Jeong Hee Shim3In Seong Han4Chung Il Lee5Dongyoung Kim6Ocean climate and Ecology Research Division, National Institute of Fisheries ScienceOcean climate and Ecology Research Division, National Institute of Fisheries ScienceDepartment of Marine Ecology and Environment, Gangneung-Wonju National UniversityOcean climate and Ecology Research Division, National Institute of Fisheries ScienceOcean climate and Ecology Research Division, National Institute of Fisheries ScienceDepartment of Marine Ecology and Environment, Gangneung-Wonju National UniversityDepartment of Marine Ecology and Environment, Gangneung-Wonju National UniversityAbstract Stratification is a fundamental process influencing nutrient availability and biological productivity in coastal marine ecosystems. In this study, we examine multi-decadal variability in winter stratification and nutrient distribution within Western margin of the East Sea (WES), using observational data collected between 1990 and 2023. Stratification characteristics were quantified using the Brunt-Väisälä frequency (N²), with particular focus on changes in intensity and the depth of maximum stratification. These variables were then analyzed in relation to environmental factors such as upper-layer temperature, surface wind speed, and East Korea Warm Current (EKWC) transport. Over the study period, stratification intensity increased at an average rate of 1.1% per year, while the maximum stratification depth shoaled by approximately 0.6% annual trends that became more pronounced after 2015. These shifts were closely linked to enhanced thermal stratification and increased EKWC volume transport. Enhanced stability of the water column was accompanied by reduced vertical mixing, which in turn intensified the nitrate gradient between surface and subsurface waters. The most marked nitrate accumulation was observed near 100 m, where stratification was strongest. This study highlights how physical oceanographic changes during winter can regulate nutrient supply prior to the spring bloom, potentially influencing seasonal productivity in marginal seas. The results emphasize the importance of long-term monitoring of vertical structure in assessing the ecological impacts of ocean variability.https://doi.org/10.1038/s41598-025-16226-8StratificationNutrient dynamicsNorthwest pacific marginal seaVertical mixingWinter hydrography |
| spellingShingle | Hae Kun Jung Changsin Kim Beom Sik Kim Jeong Hee Shim In Seong Han Chung Il Lee Dongyoung Kim Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea Scientific Reports Stratification Nutrient dynamics Northwest pacific marginal sea Vertical mixing Winter hydrography |
| title | Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea |
| title_full | Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea |
| title_fullStr | Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea |
| title_full_unstemmed | Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea |
| title_short | Fluctuations in stratification and nutrient dynamics during the pre-bloom period in a Western margin of the East sea |
| title_sort | fluctuations in stratification and nutrient dynamics during the pre bloom period in a western margin of the east sea |
| topic | Stratification Nutrient dynamics Northwest pacific marginal sea Vertical mixing Winter hydrography |
| url | https://doi.org/10.1038/s41598-025-16226-8 |
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