Rockweed: underwater forest or industrial commodity?

Dr. Robin Hadlock Seeley grew up in Maine and has dedicated her life as a scientist to the preservation of coastal ecosystems—in particular a form of seaweed called rockweed. Severine von Tscharner Fleming is a farmer and activist whose farm is on the Maine coast where rockweed is being harvested by the ton and shipped all over the world. What is the function of rockweed in ecosystems, and what would sustainable harvesting—as opposed to extractive mining—of rockweed look like?