Rod, I love the graphic design feel of this image. And the lighting and background are very nice too. If I had to pick on anything it would be to wish for just a bit more DOF (say f9 or 11) to bring the wing into focus. I realize, though, that stopping down might have been difficult under the conditions.
Terrific terrific detail and I really don't think any more sharpening is necessary. Those neck and head feathers are so fine, like fur, that it may be assumed the area is too soft. I love the intimacy of this image. I don't think I've seen an anhinga's eye captured with this level of detail. Thanks so much for sharing this one!