Suitability of microalgae as food for bivalves based on size and hardiness

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K15577
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Mie University
• Principal Investigator: HOUKI Shouji 三重大学, 生物資源学研究科, 助教 (10809354)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 二枚貝 / 食性 / DNAメタバーコーディング / 珪藻 / 餌料環境 / アサリ / アコヤガイ

Outline of Final Research Achievements

Species compositions of microalgae which are fed by Ruditapes philippinarum (larvae to adults) and Pinctada fucata martensii (settled spat to adults) in the natural environment, as well as the suitable size and hardness of microalgae for feeding and digesting were examined. The results showed that the available food for bivalves in their early life stage (larvae to small juveniles) was limited to small and fragile microalgae with diameter of less than about 8-15μm and a strength of less than about 70-100μN. On the other hand, bivalves that grow to more than a few millimeters in shell length are able to feed on planktonic diatoms forming long colonies exceeding 100μm, and digest benthic diatoms with a hard cell walls exceeding 300μN.

Free Research Field

海洋生態学

Academic Significance and Societal Importance of the Research Achievements

餌料環境の正確な把握は、危機的な状況にある我が国の二枚貝類の増養殖における緊急かつ重要な課題と位置付けられている。ところがこれまで、天然海域における二枚貝の具体的な餌料すら明らかになっていなかったため、餌料環境の正確な評価は不可能な状況にあった。餌として適した微細藻類の特徴を二枚貝の成長段階ごとに解明した本研究の結果は、沿岸域への栄養塩供給方策の二枚貝資源におよぼす効果の正確な評価や、海面養殖における信頼性の高い環境収容力の算定など、餌料環境に起因すると想定されている二枚貝増養殖を取り巻く諸問題の解決のための不可欠な知見となると期待できる。