Algae is a term for a diverse group of organisms living in the ocean. Benthic algae usually cover hard bottoms from the seashore down to 20 to 40 metres depth. Below that level, insufficient sunlight hampers their growth. Where the bottom is sandy or muddy, the benthic algae cannot attach themselves as they have no roots.
Benthic algae are a source of food, energy and cover for many organisms. In this way, the productivity of the benthic algae in shallow waters directly or indirectly affects the efficiency of the entire marine ecosystem.
Benthic algae are generally split into three main groups: green algae, brown algae and red algae. Benthic algae have been utilised in Iceland for centuries. They were used as sheep food, fertilizers and for burning in stoves.