I chose this image for a structure-texture entry because not all structures or textures are man-made. The swan could be interpreted as the "structure" since by its movements it alters the "texture" of the water ripples around it. I was very lucky with the sunset light though: I have several shots which are very similar in terms of framing to this one, but dull overcast light makes them somewhat bland.

BTW I know that from all the specks in the water, it looks like I used a very dirty lens! LOL! Actually my kit is spotless (almost) and the specks were all floating on the surface of the water. I could clone them out, but it would take forever... I figured they could stay in and add to the "natural texture" theme. ;)