Lovely colors and texture you've captured here..I like this sort of upload..check out my gallery if you don't believe me ..lol...there is a lot going on underneath our feet that we don't often see or expose to the world..nice job :)PJ
I've collected "pretty rocks" since childhood...and so I really like this kind of subject. So many of the pebbles in this pic look so interesting! However, I don't much like the seaweed...it looks slimy to me and reduces the attractiveness of the pebbles. Also, while not suggesting that you arrange the pebbles, I wish you had found a spot that seemed to have stronger "lines" (via shadow or color or flow) to help my eye travel through the composition.