The indirect removal of nutrients is one of the processes through which oysters can extract nutrients from tidal environments. Oysters remove nitrogen and phosphorus from the water column by digesting particulate organic matter and phytoplankton (algae). Some of these nutrients are then absorbed into oyster tissues and shells. The nutrients are then permanently lost from the system when oysters are harvested.
Kelp will grow 30 times faster than terrestrial plants, at a rate of 2 feet per day. The same offset may be achieved by planting kelp throughout 10% of the oceans (4.5 times the size of Australia). In addition, the kelp would support a 2 megaton annual fish harvest and reduce ocean acidification.