There are bubbles/foam around the edge of my refrigerated maple syrup and I'm wondering if it's safe to eat. The maple syrup came from a can and was transferred into a dispenser like the one shown in the first photo maybe a week or two ago. The lid does not seal hermetically. The bubbles were not there when it was originally transferred.
Assuming the can and the syrup were in good shape when opened, it's not going to mold in the refrigerator in a week's time.
Although you say the bubbles weren't there when transferred, do you just mean they weren't on top like this? Whenever I transfer syrup, I make lots of bubbles inside from the pour. In addition, many of the pour bubbles are tiny, so they rise very slowly (hours to days).
I think those are bubbles created from the transfer that took a few days to reach the top. Surface tension holds them to the side of the container. Unless there were some other oddity (changed color, changed smell, changed taste), nothing in that photo worries me.
Do you have anything else in your refrigerator that would cause the maple syrup to be unsafe to eat? Unless you're putting raw chicken above your unsealed jar of maple syrup, or you have a serious mold problem, there is no reason why the syrup would be unsafe to eat.
As to why the bubbles formed in the first case, I would guess a combination of quarague's and BowlOfRed's answers: When the syrup was transferred, a bunch of tiny tiny bubbles were created. They slowly merged and floated up, and then in the refrigerator the liquid and sugar on the bubbles froze or crystalized giving you spheres of air coated in sugar.
Additionally, molds that do grow on maple syrup are non-toxic and can easily be removed. Simply inspect the surface of the syrup for strange floating substances, remove them, and transfer the syrup to a clean container.
Check how solid these bubbles are. Maple sirup is essentially made of sugar and water. My guess would be that a little bit of water evaporated and the bubbles are mostly sugar crystals. In that case the bubbles would feel relatively hard and crunchy (so very different from for example soap foam). Similar effects can also happen in liquid honey, part of the sugar just crystallizes. If this is the case this is totally harmless and safe to eat.