Silicon and Nitrogen Dynamics in Hiroshima Bay: Impacts of Aquaculture and Water Column Stratification

School of Integrated Art and Science Hiroshima University Higashihiroshima, Japan

^* B233206@hiroshima-u.ac.jp

Abstract

The silicon-to-nitrogen ratio (Si:N) is crucial in shaping phytoplankton community structure and maintaining the stability of coastal ecosystems. Hiroshima Bay, as a typical coastal area, is influenced by factors such as river discharge, aquaculture, and industrial pollution, altering the distribution of dissolved silicon and nitrogen. Despite extensive research on nitrogen and phosphorus cycles, silicon’s dynamic changes and ecological implications remain underexplored. Therefore, this study analyzed the spatial distribution and vertical variation of silicon and nitrogen in Hiroshima Bay through water sample collection, experimental analysis, and statistical modeling. The results show that aquaculture has a notable impact on silicon consumption and concentration changes, while the interaction between sediment and water, as well as water stratification, is crucial in regulating silicon availability. Furthermore, the Si:N ratio varies with seasons and climatic conditions, providing new insights into the interactions between silicon and nitrogen and their effects on the ecosystem. Besides, it offers guidance for improving coastal water quality management, optimizing aquaculture resource use, and addressing eutrophication.