[A-CG40] 沿岸海洋生態系－1．水循環と陸海相互作用

[ACG40-07] 気仙沼湾奥部の干潟域に形成される底生生物巣穴からの栄養塩輸送量の定量

湯場 大洋¹、竹野 圭祐¹、中島 壽視¹、邉見 由美²、*杉本 亮¹ (1.福井県立大学海洋生物資源学部、2.京都大学フィールド科学教育研究センター)

キーワード：生態系エンジニア、海底湧水、陸海境界領域、アナジャコ属

Burrows of benthic animals are spread across the seafloor in coastal ecosystems worldwide. Although the filtration effect through the burrow of the upogebiid shrimp is thought to be significant in nutrient dynamics in coastal ecosystems, little field survey quantifies nutrient fluxes between the burrow and the overlying water. Here, we show the advective fluxes of water and nutrients from the burrow of Upogebia yokoyai at the tidal flat in Kessennuma Bay, assessed by the handmade small current meter. The water flux from the burrow was 217±83 ml burrow^-1 h^-1 in the spring tide and 523±73 ml burrow^-1 h^-1 in the neap tide. These fluxes were five times higher than the seepage flux from the no-burrow sediment measured by the same current meter. The averaged total fluxes (burrow + no-burrow) of dissolved inorganic phosphorus (DIP) and nitrogen (DIN) from the seafloor were +23.63 mmol m^-2 h^-1 and +1.50×10³ mmol m^-2 h^-1, respectively. Regarding DIN, the fluxes of nitrate and ammonium were negative and positive, respectively. Furthermore, the total fluxes of DIP and DIN from the tidal flat (~2000 m^-2) were 0.89 and 0.65 times higher than those from the rivers. The fluxes from animal burrows accounted for approximately 31% of DIP and 16% of DIN, although burrows occupied only 5% of the seafloor surface in the tidal flat. These results show that animal burrows would be non-negligible nutrient sources in coastal seas.