"known for intense diatoms blooms suspected to enhance CO2 sequestration" You're both right, a bit. It's a near certainty that these cells "eat" CO2, that's ho

"known for intense diatoms blooms suspected to enhance CO2 sequestration" You're both right, a bit. It's a near certainty that these cells "eat" CO2, that's how all other plankton works. They eat CO2, live their life, die, sink to the bottom where their remains slowly sink over millions of years. This definitely removes CO2 from the oceans (storing it packaged on the bottom) and should remove CO2 from the atmosphere too due to the enormous contact surface. What is not known is how much it affects CO2 concentrations and while massive algae blooms have been occurring more and more, we're not very sure why and what will happen with them in the future.