Julie-I don't know if beavers eat lotus or not but I do know they are bad for a pond with a levee and most vegetation in the area. They'll tunnel into the levee and the pond will blow out. Real problem.
lynn

Julie, perhaps Muskrats ate your lotus since they mainly eat aquatic plants? Beavers mainly eat tree bark.

Here is a link that might be useful: Muskrats

I wonder about the muskrats too. I've heard how delicious lotus are, and it could be any number of animals that ate them.

Yes, beavers definitely eat lotus plants. They start with the lotus flowers themselves and then will eventually eat the remainder of the plant. I know because, well, I have watched them do it in our pond. With all types of options for them to eat in our acreage, they prefer the lotus above all else. Also, as someone said, they burrow into the levees, which can cause problems. That being said, there are upsides to having beavers for us. They keep the dam at the back of our swamp intact to prevent the swamp from turning into a mud pit. And for us, without beavers, the lotus plants get completely out of control in both our pond and swamp. Oh, and over time, they grow more comfortable with our presence and add some interest to the yard.