Ocean Acidification Threatens Diatoms – Spectrum of Science

In large parts of the ocean, diatoms, also known as diatoms, are the largest group of unicellular organisms. A research group led by Jan Taucher from the GEOMAR Helmholtz Center for Ocean Research in Kiel has now investigated how ocean acidification affects these organisms and how it influences the biogeochemistry in the seas. Their experiments, observations and models independently suggest that ocean acidification will have far-reaching consequences for the export of elements to the deep sea.

Each diatom cell is surrounded by a silicon dioxide (SiO₂) wrapped. How well the silicon (Si) remains in the biomineral depends on the pH value of the surrounding water: the more acidic the seawater, the less silicon dissolves in it. While these properties of diatoms are well known in marine research, no one had previously investigated how they affect future biogeochemical cycles associated with ocean acidification.

Diatoms convert carbon dioxide dissolved in water very efficiently into organic carbon compounds through photosynthesis. Together with silicon dioxide, these form particles from dead diatoms, which then sink rapidly to the depths. Diatoms are therefore considered to be the most important engines of a “biological pump” that transports carbon into the deep sea, where it remains bound for a long time. …