Well, the shapes on the water surface are actually both reflections and boats waving with the ripples. The long exposure of course blurred them. The dashed horizontal line is the trace of a ferry boat passing by... The effect is quite puzzling, indeed: I'm glad you liked it, since it might also annoy somebody.
Sometimes you have to compromise in night time photography. With scenes like this one, there usually is just way to much traffic of some sort, to be able to block out all of the light of passing vehicles by temporarily holding something in front of the lens. I am not bothered here.