Open fermentation and low o2 brewing

[BucksIPA]

Anyone with experience on open fermentation and dissolved o2 of this? Are they allowing o2 from the atm to dissolve into the open fermentation , and allowing yeast to get to that at the surface and reproduce, somewhat preserving the below wort from oxidation, then moving to closed ferementation after reproduction.

Or are they dissolving oxygen completely before?

Thanks