Considering Acacia plantation from marine fishery and nutirent flow -A case study in central Vietnam-

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K18250
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 80010:Area studies-related
• Research Institution: Kyoto University
• Principal Investigator: Okamoto Yuki 京都大学, 地球環境学堂, 研究員 (00635500)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: ベトナム / カキ / アカシア / 栄養塩類 / 湾 / プランテーション

Outline of Final Research Achievements

Effect and nutrients input/loads from Natural Forest and Acacia Planation into the oyster aquaculture fishery and coastal environment was examined in central Vietnam.
As a result, 1) differences in land forest types did not show any differences in nutrient loads (low impact), 2) oysters were cultured, inhabited in his bay and estimated production was around 4000 tons/bay, 3) PO4 in bottom water was suggested as a characterized nutrient source in this bay, and 4) fertilization in Acacia plantation was limited in amount and period with specific contract based management with ownership which support local residents to implement to Acacia plantation as one of their livelihood activities in study area.
Therefore, in terms of negative impacts in nutrients loads in the coastal water and oyster production, there were not observed in this study site.

Free Research Field

環境

Academic Significance and Societal Importance of the Research Achievements

ベトナム中部沿岸域にけるアカシアプランテーションが沿岸漁業環境に与える影響についえ具体的に調べた研究はこれまでになく、従来の考えでは、プランテーション農業は、モノカルチャーであること、多量の施肥など、ネガティブな側面が取り上げられてきた。
本例で取り上げたベトナム中部の事例では、沿岸域で養殖されるカキ、プランクトン、そしてその栄養である栄養塩類にフォーカスして分析した結果、自然林、アカシア林ともに沿岸域への栄養塩類の負荷は小さいものであることが明らかになり、主な栄養塩の起源は底質であることが示唆された。地域性が反映された結果でもあるが、思い込み・想定を覆す重要な事例を掲示出来た意義は大きい。