Critique per req:
1. Not a bad image; I think however since the turtle is the interesting aspect, you'd be better off to zoom in tightly, and eliminate the large open area; the lilly pads and branches are of limited interest.
2. Nice work with the reflection, but not the ideal time of day for this pose; you can see a very bright/blown area on the top of his back, and deep shadow on his right side. Depending on the distance, a fill-flash might have helped with this image. Additionally, it needs to be leveled.
3. Again, as per #1, too much image, not enough subject. Definitely zoom in tighter on the web. The B&W conversion is nicely done.
Overall, not a bad group of images. You seem to have a basic understanding of the technical side, time to focus on the composition/artistic side. As an aside, remember that for most photography, your best times are early morning, later afternoon. Mid-day produces a very strong light with harsh shadows.
Just my $00.02 worth - your milage may vary.
~John