Seaweed

When we were at Ardentinny earlier this week, we noticed that the waves breaking on Glenfinart beach were brown with weed and other vegetable matter; today on the shore at Toward the weed was piled so high at the water's edge that even if I'd felt like paddling I'd have had difficulty clambering over it.

Why does this happen? Is it a period of sustained onshore winds, or a storm somewhere churning the stuff up from where it grows?

I feel there must be some knowledgable soul out there, blipping away ...