Note
The rhodophyte Gracilaria tikvahiae is presently being cultivated in an aquaculture system to study its feasibility as
a source of biomass that can be fermented to produce methane gas. Because nitrogen and other nutrients are conserved
within the digester, the digester residues are a rich source of plant nutrients. Rather than being only waste products
that require disposal, these residues can be recycled within the aquaculture system to produce additional seaweed
biomass or, alternatively, might be used in agriculture to replace conventional fertilizers. For every 100 g of
nitrogen added to the digester in the form of Gracilaria, 73 g of nitrogen were completely recycled from the digester
back to cultures of Gracilaria.