Can I reduce the amount of sea salt without affecting the bread in any way?

Made the Sourdough Bread with AP flour and reduced the salt from 9 to 8 grams. I'm very pleased with the result and the taste was spot on, although I'm not sure I'd reduce it further unless I try Lori's advice. I added sunflower seeds and replaced part of the AP with WW and overnight proofed in the fridge, baking the next morning. This might be my go-to bread, especially when I only want to bake one loaf. Ready to try the schiacciata next! Thanks to all who helped me out here.

I'm a bit late to this - but if you want to reduce sodium in baked goods, consider replacing some of your regular salt with potassium chloride. That's another sort of salt, and chemically it reacts in baked goods like bread in an almost identical manner. It will still help regulate the yeast, and add the taste enhancement you want- without the sodium. You can use something like Morton's Lite Salt, or mix up your own 50/50 mix using sea salt if you wanted. I've done this for years, to help with my late husband's blood pressure control. In small amounts used for baking, I've never noticed a taste change. Now for topping purposes, I prefer regular salt crystals, but at least this gives you an option to consider.

As HalfPint said, you can reduce the salt, but don't adjust too much because it'll affect dough strength (reduced) and fermentation rates (increased). If it were me, I'd leave the salt in the dough as-is, but skip any salt sprinkled on top.

Yes, you can to a degree. The only effect might be the proof time. The dough might proof faster without salt, since salt can slow yeast growth. But you can get away with less salt. That said, 9 grams of salt is about 1 1/2 tsp, which is not a lot of salt for that much flour (520g).