If it was an incandescent bulb, it's not likely to be mercury, but rather tungsten (if acidic water) or more likely lead poisoning. Both metals have effect on respiratory systems in mammals. Fish oxygen transport is another matter. Not that it really matters what it was.
If I were you I'd get everything out of that tank and filter, swap them over to the backup, and then replace anything you can and bleach everything not replaceable. Set all the equipment out in sunlight or a day or three, and then start repopulating your bacteria colony. Just start over.