As Thrik says.
Seriously, how is something not in the water displacing said water. Any ice floating above the water will add to the sea when melted, I don't see how you don't get this. By your logic, if I stick my hand in a bucket of water, an entire Joshi's worth of water will be displaced. Seriously, ask a science teacher, or read a book, or just anything that might educate you before making such claims.