I heard somewhere(can't seem to find it) that the rate of gas exchange in saltwater vs. freshwater is 50%(something like that) lower. Also that saltwater has a much lower capacity to hold oxygen, meaning that we have to do as much as we can to facilitate the gas exchange in our aquariums. This is one of the primary dangers of power outages - oxygen depletion - without the current provided by powerheads/filters/pumps the oxygen in our aquariums is quickly used up and livestock can die. So to get back on topic, anything that you can do to help with oxygen exchange, like run without lids, is helpful to your tank.
Also the glass on your lids cuts down on the light entering your aquarium. The more light the better. One solution that many use is to purchase a fine netting made of clear plastic and use a screen frame to construct lids that allow for oxygen flow and keep fish in the tank but don't cut down on light much.