PROBLEM TO BE SOLVED: To provide a modifier capable of improving a bottom sediment environment of a habitat of a bivalve into an environment suitable for inhabitation of the bivalve, without suppressing activity of the bivalve digging into sand such as a freshwater clam.SOLUTION: There is provided a bottom sediment modifier of a habitat of a bivalve digging into sand, which is a granular material containing shell powder of the bivalve digging into sand, and magnesium hydroxide powder and/or magnesium oxide powder.SELECTED DRAWING: None【課題】しじみなどの砂地を潜る二枚貝の活動を抑えずに、その二枚貝の生息域の底質環境を二枚貝の生息に好適な環境に改良することができる改良剤を提供する。【解決手段】砂地に潜る二枚貝の貝殻粉末と水酸化マグネシウム粉末及び／又は酸化マグネシウム粉末とを含む粒状物である砂地に潜る二枚貝生息域の底質改良剤。【選択図】なし
