Always be prepared

Sitting in a gondola, you really don't have much in control.  You have to sit tight, you can't steer, you can even stop or slow down.  The only thing you can do is to hold on to your camera and be prepared for the changing scene in front of you.  The gondolier in the shadow would soon be in the sun again.  The arch of the bridge would be gone in a second.  The gondolas would be stuck together.  Everything would be completely different in a few milliseconds. I never shoot in a burst.  I always shoot single frames.