Potential value of macroalgae cultivation in the Chesapeake Bay area

Shellfish (clam and oyster) aquaculture is promoted in the Chesapeake Bay and (Virginia) coastal bays. While the shellfish is filtering water, dissolved nutrients are release back to the water column. Macroalgae (i.e., Gracilaria and Agardhiella) takes up these nutrients, and are blooming near the shellfish farms in the lower Chesapeake Bay and coastal bays. Comparing to microalgae, macroalgae is easier to be harvested, and has a market globally. By harvesting the macroalgae from the water, nitrogen and phosphorous nutrients are also removed from the water column. The potential of macroalgae as bio-mediator for nutrient management purpose and a second crop for the shellfish farm was tested at different sites of the Chesapeake Bay and coastal bays. Gracilaria has a relatively high salinity tolerance to grow in salinity 15 and higher. However, in the high turbidity Chesapeake Bay water, the growth of Gracilaria is strongly light limited, and Gracilaria may not naturally spread to upper Chesapeake Bay. Floating culture methods of macroalgae can support the cultivation of Gracilaria to more eutrophic water in the Chesapeake Bay for nutrient management purpose.