Recently we had a lot of foam in out cooling water towers at work. So I decided to have a look at what sea foam was. It seems to be a breakdown of algee and microbes and stuff. The strings of lipids (from the breakdown of cellular barriers for example) react with the abundance of salt in the presence of acid (carbon dioxide) forming a multitude of varied soaps. Then with a bit of extra agitation they foam up.
then again I could be wrong, its happened before.