What pond plant is this? (see pic)
What a lovely plant! Unfortunately, I'm not familiar enough with pond species to identify it. I will reassign your question to another expert that I think might know.
Good luck with your pond.
That is floating water primrose. It is a native, but highly problematic plant species that can quickly cover ponds. It does not provide much use for fish or wildlife. Use glyphosate plus a non-ionic aquatic surfactant to kill it before it becomes established.