This is NOT the worst science I have ever read. It’s also not the best. BUT I think it’s worth trying. Here’s why:
Many oceanic ecosystems have just a couple limiting factors, such as oxygen+ sunlight, or iron+ temperature, and so on.
In certain areas of the ocean, which they think they have identified, the limiting factor is iron; ie a key ‘fertilizer’: in other words there’s not enough iron to let phytoplankton grow as fast as they could, all other critical factors being plentiful. In other parts of the ocean it might be temperature, dissolved CO2, pH, etc etc. In another example, the limiting factor for growth in a corn field in Nebraska, in a normal rainfall year, is the LACK of CO2 in the ambient air. (REM: Orchid greenhouses are frequently augmented with CO2 to enhance growth).
The point is that it *DOES* make sense to fertilize the oceans with the missing nutrient. Growing more algae will indeed cause the photosynthetic algae to ‘fix’ CO2 into the ‘bodies’ of the algae, and those will eventually sink to the bottom of the ocean.
BUT!!!
the balancing act is that creating an artificial bloom creates an enhanced demand for OXYGEN as well during the night hours when these additional organisms continue to respire in the dark. THAT causes mass die-offs of other organisms ... i.e., fish kills. This is especially true in aquatic ecosystems.
Still, don’t throw this one out.
FWIW, the same thing could be accomplished by smartly ‘dumping’ municipal black water sewage into the ocean at the right times of the day (NOT night).
Does algae actually consume oxygen or is it bacteria eating an oversupply of dead algae at night causing the problem? This is a problem for fish ponds but does it apply to the deep open ocean? The ocean is highly buffered so it seems hard to believe the oxygen ppm could drop to fish killing levels overnight.