Great take on the theme!
The art is also great, very cool what you were able to accomplish in just a week.
Maybe some trash could fall at a slower rate / stay floating higher above the floor to keep the player moving to more places / giving the sea creatures trash that's easier to grab for them, or even for them to get stuck in.
I saw a comment of yours with a list of things you'd plan to implement if you were to continue working on the game, a lot of it sounds really nice!
Overall I think it's a fantastic project, good job!