Hi Remi,
This is a great image, I love seeing water frozen in time. The colour of those two shells is also rather fantastic. There are a couple of things that concern about this photograph though.
The first thing that I notice when I look closely at this image is the noise. You made the photographs at 6400 ISO which is getting a bit high for your particular camera. What I would suggest you could try next time in a similar situation is to use a slightly lower ISO (1600 perhaps) and compensate by using a wider aperture and a slightly slower shutter speed. Remember that every time you halve the ISO (ie, from 6400 to 3200), you compensate by either opening the aperture one stop (ie, from f11 to f8), or by slowing the shutter speed by one stop (ie, from 1/3200 to 1/1600).
With this particular image you could have made the photograph at 1600 ISO and used an aperture of f8 and a shutter speed of 1/1600 of the second and still achieved a very similar result. The advantage would be that you would have less noise and this could be crucial when it comes to making larger prints in the future. Also, if you use lower ISO’s you will get better colour saturation.
One of the great advantages that we have these days is that in Photoshop we can pretty much do anything to make a photograph better. By going to f8 you will get less depth the field, and that will make those shells in the lower left even more out of focus. What you can do though, is use a technique called focus stacking.
What this involves is taking several photographs of the subject, preferably from a tripod mounted camera, with each photograph capturing in focus a key element of the scene. You can then use Photoshop to merge the images together while selecting the sharpest element from each from to create a result that is often better than you would ever achieve with the best lenses and technique.
Good Effort… Image Doctor