This is a heart wrenching, but a nevertheless beautiful In Memoriam piece of art.
The shadows and lighting are essentially perfect, so I cannot give you any advice in how to improve them because I reckon that they don't need any.
I think that maybe the only tips I can share is next time you can draw Ariel's shoulders narrower and add a deeper curve to the juncture where her neck meets her shoulders, which will make her look closer to her young age, as she is now she looks more solidly built so she appears older, in her late 20s.
Oh yes your dad I thought you meant Kenneth Mars who passed away 3 yrs ago, I was like something aint right. But anyway still. I feel your grief and sadness, I grief a lot of deaths myself. My condolences.
Deep and intensely emotional.... Thank you for doing this concept... the only thing I would say is there's something a bit off with the shoulders and well her face is gorgeous but looks a bit young(small)................I LOVE ALL YOUR ARTWORK AND ALWAYS AWAIT FOR ANYTHING MERMAID...BUT DOING BODY POSITIONS LIKE THESE ARE A BIT TRICKY WHEN IT'S A CLOSE UP