[A-CG41] 沿岸海洋生態系－2．サンゴ礁・藻場・マングローブ

[ACG41-06] 人間活動の影響を受けた沿岸域のpCO₂およびDOC変動に養殖海藻・天然藻場が与える影響

*渡辺 謙太¹、所 立樹^2,1、茂木 博匡¹、桑江 朝比呂¹ (1.港湾空港技術研究所、2.国立環境研究所)

キーワード：炭素循環、海藻養殖、ブルーカーボン

Carbon cycles in coastal waters are highly affected by human activities. Primary production regulate CO₂ sink–source behavior in coastal waters, but the contribution of macrophyte habitats including seaweed aquaculture to coastal carbon dynamics has not been understood. We investigated the variations in pCO₂, carbonate chemistry, and dissolved organic carbon (DOC) in human impacted coastal waters. We analyzed the biogeochemical drivers for the variations in these carbon parameters using generalized linear models (GLMs). Cultivated seaweed metabolism was quantified with in situ field-bag experiments. Cultivated seaweeds took up DIC and released DOC. Our GLMs estimated that macrophyte habitats contributed to the enhancement of in situ atmospheric CO₂ removal during the productive period in a semi-enclosed embayment but not in an open coastal water due to the efficient water exchange. Our findings suggest that the DIC uptake rate by macrophyte habitats does not directly equate to the CO₂ removal rate from atmosphere due to the time required for air–water CO₂ equilibrium and the transport, implying the future needs for technological developments in tracing and modelling of macrophyte-affected water.