Used to cover the pond many years ago with a "cold frame" type green house, but decided the dark was worse when I got white fungus growing inside the pond, on the walls, and on the fish! It went away once I took the top off. Then I thought I never get fungus under the ice in winter cause the sun can still shine threw the ice and keep fungas away. I decided the ice was good, to a certain extend, like 2-6 inches ok so long as there is lots of natural open holes and water running like the creek. I also try to keep things as natural as possible, and that includes a few leaves too. That year I got fungus, I also went crazy and covered everthing tight so not a leaf could fall in my pond, but I decided that too could be a problem, as some leafs good for pond life. So now for the last two decades I allow some leaves in the pond for the winter, keeps the SnailS haPpy!
JW I will try to get pictures of birdies tomorrow in the daylight, there sleeping now zzzzzz