[A-CG40] 沿岸海洋生態系─１．水循環と陸海相互作用

[ACG40-04] Estimation of contribution rate of Submarine Groundwater Discharge to Ulva pertusa using nitrogen stable isotope ratio analysis

*石田 健大¹、竹内 優¹、中島 壽視¹、杉本 亮¹、小林 志保²、木庭 啓介³、福島 慶太郎³、富永 修¹ (1.福井県立大学、2.京都大学、3.京都大学生態学研究センター)

キーワード：海底地下水湧出、生物生産、δ15N

In recent years, the influence of Submarine groundwater discharge (SGD) has attracted attention as a source of nutrient that supports biological production in the coastal area. However, the information about the direct influence of SGD on biological production is poor. In this study, in order to examine how much the groundwater contributes to primary production, we collected the primary producer Ulva pertusa in Yuza, Yamagata Prefecture, where the groundwater is abundant. On August 27, 2018, we collected sea water, ground water and ambient water around Ulva at five sites in the Yuza Coast and simultaneously measured salinity, water temperature, ²²²Rn concentration which is the indicator of undergroundwater. We also analyzed the nutrient concentration, of sampled water and of Ulva. Finally, we estimated the contribution of groundwater to Ulva using two source Bayesian Mixing model. The value of nitrate nitrogen derived from SGD was low. In the high SGD sites (²²²Rn concentration 427 ~ 22000 Bq/m³) and the low SGD sites (²²²Rn concentration 38.1 to 210.6 Bq/m³), the of Ulva was 2.1 to 3.6 and 5.4 to 6.9, respectively. It was suggested that nutrient derived from SGD contributed to the production of Ulva in Yuza.