Benthic marine diatoms: ability to use dissolved silicate, and silica cell wall dissolution

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06185
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 40030:Aquatic bioproduction science-related
• Research Institution: Kagawa University
• Principal Investigator: Yamaguchi Hitomi 香川大学, 農学部, 准教授 (50464368)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 海産底生珪藻 / 珪酸 / 珪藻殻

Outline of Final Research Achievements

This study examined (i) the ability of benthic diatoms to use dissolved silica (DSi) and (ii) dissolution of the benthic diatom silica wall. The aim was to compare these characteristics with those of planktonic diatoms.
The effect of DSi on the growth of five species of benthic diatoms indicated that the half-saturation constant for DSi (Kμ-Si) was about 1 μM, irrespective of species. These values are similar to those typical for planktonic diatoms. That is, at least in considering Kμ-Si, diatom use of DSi does not depend on whether diatoms are benthic or planktonic.
Diatom frustules were suspended in seawater and dissolution over time as biogenic silica was monitored for 14 species. The dissolution rate of the labile fraction of frustules dissolving within the initial stage tended to be slower in the benthic than in the planktonic species, though variations were large among species. These variations were attributed partly to species-related differences in specific surface area.

Free Research Field

沿岸物質循環論

Academic Significance and Societal Importance of the Research Achievements

本課題を通じて，底生珪藻を介在する珪素循環の一端が，浮遊珪藻との比較という観点から明かされた。沿岸域の珪素循環に着目したとき，「海底生活を営む浮遊珪藻が底生珪藻である」という見方は，場合により正させるべき必要があることを本課題の結果は示している。まだ検討の余地を残すものの，本研究では特に珪藻細胞死後の珪藻殻の溶解速度には，浮遊性と底生性種間に系統差がある可能性が示された。