foamy bubles on surface of pond

Question
dear sir i have noticed that i am getting foamy bubles on the surface of the pond, its like white plodges of dots, can you please explane why this is accuring, thank you

Answer
Hi there!

That could be caused by bacteria growing in the water.
But in order to help you better, I need you to answer me a few questions:
Is this pond something that you made?
If so; does it have a filtering system?
Is there any fish in it?
Please describe your pond.

Thank you.

Carlo