this is a wonderfully serene and calming image, one that I was immediately drawn to today. thanks for sharing. The panoramic crop is very fitting. nice compositional choice.
I would not suggest cropping this image. By doing so, then you would just have a photograph of 2 swans...and although it would not be a bad picture of two swans, I think you have more interesting textures and visual movement happening in the water, mostly over on the left side! Sure its alot of negative space, but that space is still working well in this image because it draws the viewers eye to ALL parts of the photograph. If that are was just pure black...I too would say to crop it and just make it a picture of a couple swans, but that interesting exploding texture in the water puts more interest to the image than the swans actually do.
another vote for culling the RH swan - and maybe just a touch of the left side to bring the main swan to the left a bit more - not too much though. THe picture seems to make more sense to me this way.
I agree with Don. The inky blackness, almost oiliness of the water was the strength of this image. The swans are secondary and provide some contrast. Nice image.