I saw this on 60 minutes a few weeks ago.

Connecticut Water Farmer on 60 Minutes

60 Minutes: Seaweed Farming, 29 April 2018, Leslie Stahl

Bren Smith has invested in vertical kelp farming.  I think this could be a potential solution to the nutrient issue in the historic Indian River Lagoon.  The vertical farming could be placed on the top of the water, provide a cover for fish (manatee?) and the mobility of the ‘farm apparatus could allow it to move to the most needed areas, too.  (Scuttle from the ole timers: causeway bridges restrict circulation and create pools of stagnancy where algae grows rampant.)

Possibly, the sea grass could help do the job that toxic algae which are responding to excess nitrates and such that flow into the lagoon – a problem that is on track for correction by 2028.

(WESH Channel 2, 2013 Reporting on Toxic Algae in Indian River Lagoon)