It is used as soil conditioners and as livestock feed. Maerl is commonly used as a soil conditioner.
Aquatic and microscopic species are cultured in clear tanks or ponds and are either harvested or used to treat effluents.
Alga culture on a large scale is an important type of aquaculture.
It is used as compost for landscaping, or a means of combating beach erosion through burial in beach dunes.
Seaweed is under consideration as a potential source of bioethanol.
Seaweeds are also harvested or cultivated for the extraction of alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance as food additives.
The food industry exploits their gelling, water-retention, emulsifying and other physical properties.
Agar is used in foods such as confectionery, meat and poultry products, desserts and beverages and moulded foods.
Carrageenan is used in salad dressings and sauces, dietetic foods, and as a preservative in meat and fish products, dairy items and baked goods.
Seaweed extract is used in some diet pills.
Seaweed is a source of iodine, necessary for thyroid function and to prevent goiter.