[A-CG43] Coastal Ecosystems - 2. Coral reefs, seagrass and macroalgal beds, and mangroves

[ACG43-06] Oxygen fluxes in seagrass and macroalgal of Omura Bay, Nagasaki, Japan

★Invited Papers

*Gregory N Nishihara¹, Yukio Inoue², Kenjiro Hinode², Kouichi Osaki² (1.Organization for Marine Science and Technology, Nagasaki University, 2.Graduate School of Fisheries and Environmental Sciences, Nagasaki University)

Keywords:Macroalgae, Seagrass, Oxygen flux

Given the interest in primary production of shallow coastal ecosystems, we investigated the oxygen fluxes in two shallow water ecosystems in Omura Bay, Nagasaki, Japan. Omura Bay is an extremely enclosed water body located in western Japan. Along the shoreline of the bay, Sargassum forests and Zostera marina meadows are abundant. They form dense stands within 20 m of the shoreline. Among the variety of instruments we deployed, an array of dissolved oxygen loggers and submersible light loggers were used to characterize the daily variations in oxygen, temperature, and underwater light. A generalized additve model was used to estimate the hourly changes in oxygen concentrations, with the results integrated over a day to estimate daily rates of net oxygen flux. Briefly, the depth integrated net oxygen fluxes within the seagrass meadow was approximately 2000 g O₂ m^-2 yr^-1, whereas in the sargassum forest, it was 500 g O₂ m^-2 yr^-1. Yearly changes in net oxygen concentration averaged 520 g O₂ m^-3 yr^-1 in the seagrass meadow and 480 g O₂ m^-3 yr^-1 in the sargassum forest. More details shall be provided during the presentation.