Joshaeus
Water hawthorn, Aponogeton Distachyos
Perhaps. The lid situation will definitely need thought next year, especially since I will likely keep fish in it next year.Perhaps if you were to bend the edges of the screen covering downwards it could not hurt anyone? Maybe even curve them under in a rolled up way.
EDIT: Maybe I could use 1/4 inch hardware cloth, fold it around the boundary of the water garden, and tie it in place with one of those bungee cords usually used for trash cans?