Applying an ecosystem-based approach to macroalgal cultivation will ensure there is a balance between the importance of macroalgae in marine ecosystems and their use in biofuel production. If not approached in this manner, macroalgal cultivation has the potential to modify habitats, reduce local biodiversity, disrupt marine foodwebs, alter water and sediment biogeochemistry and introduce alien species into coastal marine environments.
However, macroalgae also have the potential to provide a cost-effective, sustainable solution to the eutrophication of coastal waters caused by aquaculture, sewage, agricultural and industrial run-off with immediate environmental benefits.
When grown in polyculture with other aquaculture efforts (e.g. fish cages/ponds) macroalgae can be used as biofilters to eliminate excess nutrients and chemical wastes. This has the secondary economic benefit of reducing the need for costly, external algal fertilization.
Successful polyculture examples include Laminaria japonica being employed to offset the negative effects of scallop cultivation in China and macroalgal biofiltration of effluent from tidal fish ponds in Tanzania.
Macroalgal cultivation has also been proposed as a means of sequestering atmospheric carbon and mitigating CO2.