https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/683 2026-07-03T21:01:13Z 2026-07-03T21:01:13Z Kim, Jun Park, Bum Soo Baek, Seung Ho https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/212928 2026-06-02T01:00:15Z 2026-08-01T00:00:00Z

Title: Seasonal succession of harmful and non-harmful phytoplankton under hydrographic water-mass variability and stratification dynamics Authors: Kim, Jun; Park, Bum Soo; Baek, Seung Ho Abstract: Seasonal succession of harmful and non-harmful phytoplankton in coastal ecosystems is closely associated with spatiotemporal variability in water-column stratification. To clarify these mechanisms, monthly surveys based on a one-year observational dataset were conducted at nine stations from the Nakdong River estuary to the Geoje coast between June 2016 and May 2017. Phytoplankton community changes were closely associated with stratification development reflecting density differences and vertical density gradients, and were rapidly influenced by freshwater input, seasonal heating, and intrusion of the Tsushima Warm Current. Stratification intensity was numerically quantified using two complementary indices: Δρ (stratification index) and N2 (water-column stability), enabling statistical evaluation of relationships between water-mass structure and community responses. RDA ordination patterns suggested that Gymnodinium spp. and Chaetoceros spp. were more closely associated with strongly stratified conditions, whereas weakly stratified and well-mixed conditions supported Cryptomonas spp. and Skeletonema spp. The genus-level associations described in this study were interpreted qualitatively from ordination patterns and community-level relationships, and statistical significance was not independently tested for each individual taxon. Monsoon rainfall in July reduced salinity and increased nitrate and silicate concentrations. Strong summer stratification supported harmful dinoflagellates such as Margalefidinium polykrikoides, although abundance declined in August following intrusion of Yangtze River diluted water. During the study period, autumn weakening of stratification and nutrient resupply were associated with increased abundance of Pseudo-nitzschia delicatissima, while winter mixing coincided with lower phytoplankton biomass and greater relative abundance of non-harmful diatoms. Alexandrium spp. became more abundant during spring when stratification gradually redeveloped. The combined use of Δρ and N2 distinguished integrated stratification strength from depth-specific stability, providing a mechanistic framework linking physical structure to biological dynamics. These findings suggest that zone-specific environmental factors contributed to differences in dominant taxa during the study period, and that the stratification index and water-column stability may serve as useful indicators for interpreting seasonal phytoplankton succession.

2026-08-01T00:00:00Z Kim, Eun Song Lee, Sang-Moo Lee, Hae-Won Park, Bum Soo Kim, Daekyung Hwang, Hyun-Ju An, Sung Min Cho, Kichul https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/212763 2026-05-20T02:00:13Z 2026-07-01T00:00:00Z

Title: AI-assisted experimental planning for two-stage cultivation to enhance photosynthetic pigment production in Dunaliella salina DSTA20 Authors: Kim, Eun Song; Lee, Sang-Moo; Lee, Hae-Won; Park, Bum Soo; Kim, Daekyung; Hwang, Hyun-Ju; An, Sung Min; Cho, Kichul Abstract: Photosynthetic pigments derived from microalgae are increasingly valued for their diverse bioactivities. In this study, we improved carotenoid production in the halophilic microalga Dunaliella salina by combining two-stage cultivation with Artificial Intelligence (AI)-assisted experimental planning. ChatGPT-4 supported experimental planning, including Response Surface Methodology (RSM) design comparison and factor-range selection. Culture conditions were optimized using Central Composite Design-based RSM, which predicted 24.24°C and 56.36 ppt as the optimal temperature and salinity conditions. Cultures grown under these conditions in Stage I (from lag to early stationary phase) were subsequently subjected to nine temperature–salinity stress combinations (18.00, 24.20, or 30.00°C × 30.00, 56.36, or 80.00 ppt) for 3 days in Stage II (late stationary phase). Pigment profiling showed marked condition-dependent differences in chlorophyll a and b and the carotenoids including lutein, violaxanthin, β-carotene, and zeaxanthin. Exposure to low-temperature and high-salinity stress (18.00°C, 80.00 ppt) produced a maximal total pigment content representing a 2.36-fold increase compared to the minimum conditions (low-temperature and low salinity, 18.00°C, 30.00 ppt). These findings demonstrate that simultaneous temperature and salinity stress within a two-stage cultivation regime enhances pigment accumulation in D. salina and suggest that AI-assisted experimental planning may support efficient optimization strategies in algal biotechnology.

2026-07-01T00:00:00Z Jin, EonSeon https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213894 2026-06-22T02:30:36Z 2026-07-01T00:00:00Z

Title: How ecological lifestyle rewires the architecture of photoprotection across the green lineage Authors: Jin, EonSeon Abstract: [No abstract available]

2026-07-01T00:00:00Z Jost, Anna B. Rodriguez, Maximiliano Kim, Taihun Baker, David M. Yasuhara, Moriaki Not, Christelle A. Karanovic, Ivana https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/211306 2026-03-17T06:00:19Z 2026-06-01T00:00:00Z

Title: Ostracod shell chemistry as proxy for coastal marine conditions of a highly urbanized megacity (Hong Kong SAR) and an agro-centric oceanic province (Jeju Island, Republic of Korea) - a preliminary comparative analysis Authors: Jost, Anna B.; Rodriguez, Maximiliano; Kim, Taihun; Baker, David M.; Yasuhara, Moriaki; Not, Christelle A.; Karanovic, Ivana Abstract: This preliminary study investigates the trace-element composition of ostracod shells (Ostracoda: Crustacea) as biogenic calcium carbonates in their role as environmental sentinels of pollution. Using high-resolution in-situ analysis, we compared two contrasting coastal systems: the highly urbanized seascape of metropolitan megacity Hong Kong (HKSAR) and the agriculturally dominated waters of rural retreat Jeju Island, Republic of Korea (ROK). The goal was to assess whether anthropogenic stress gradients affect trace element-to-calcium ratios (E/ Ca) in the carapaces of shallow-marine Neonesidea Maddocks, 1969 species. Hereby, the focus is laid on potential differences in the effects of extreme urbanization and extreme agriculturalization. We analyzed 12 trace elements commonly incorporated into ostracod shells using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Only Mn/Ca, Mg/Ca, and Ni/Ca ratios showed strong correlations with specific seawater physicochemical parameters. Notably, Mn/Ca differed significantly between the two sites, seemingly driven mainly by variations in nitrite nitrogen levels. This suggests that Mn incorporation is sensitive to pollution source, urban versus agricultural, though species-specific uptake effects cannot be excluded. No significant differences in elemental uptake were found between adult and A-1 juvenile stages of Neonesidea mutsuensis Ishizaki, 1961 or Neonesidea elegans (Brady, 1969), supporting the use of both age groups in environmental reconstructions and increasing potential sample yields. While remaining empirical and exploratory, our tentative findings suggest that ostracod geochemistry holds promise for marine pollution monitoring and cautiously supports the application of ostracod Mn/Ca ratios to reconstruct anthropogenic, particularly nitrogen-related, impacts in nearshore environments using sediment core records.

2026-06-01T00:00:00Z