A really interesting shot. The white band of sky unfortunately draws too much attention away from the subject, and there is more detail there that can be recovered. You could also crop out the sky entirely and also eliminate the curving horizon. Another crop or cloning of the barrier at the bottom border will produce the maximum impact and concentrate entirely on the subject material without adversely affecting the overall image.
Think about the photo before and after, never during. The secret is to take your time. You mustn't go too fast. The subject must forget about you. Then, however, you must be very quick.
Henri Cartier-Bresson
Snapshooter's right about the cropping and it is a very interesting shot. I'm still guessing as to what it means. I know some members don't care to post much with their submissions, and others don't care to read long posts, but it might be nice to understand the purpose in what these people are doing with these donkeys on a beach, if you had that information available. That aside, your light, color, and DOF on this are well done.
If you've ever wanted to make a difference but found it hard to believe that one person could... check out the Kiva Team Caedes discussion thread and discover that anything is possible.
Ed.