The Importance of Seaweed

For hundreds of years seaweed has been used for food and for fertiliser. Today many countries like Australia are looking at seaweed more closely because it has wider uses.

Most people come into contact with seaweed when it is piled-up on the beach. People can become annoyed at the rotten, smelly mess. However, this smelly mess has a vital role in the ecology of the coastline.

Seaweed or, as it should be called, marine algae is full of nutrients and when it breaks down provides an invaluable source of food for many creatures living along the seashore.


There are more than 900 seaweed species found around Australia. They range in size from as tiny as a pinhead to 30 metres in length. Many of these seaweed species can be eaten and many have other commercial uses.

Seaweed, unlike seagrasses, have no roots, flowers, leaves and stems. They reproduce by producing spores, gametes or by fragmentation. They get their food by absorbing it directly from the ocean waters. Seagrasses are a more complicated plant. They are really underwater flowering plants. Seagrasses have roots and attach themselves to the seabottom whereas seaweeds just float freely about. They do have a holdfast anchor which allows them to hold onto seagrasses and rocks.

Seaweed can be found in many parts of our diet. A lot of seaweeds are rich in protein and contain many vitamins and minerals. These high levels of vitamins and minerals have made seaweed an important part of many health food products.

The thickening properties that seaweed has is used in the making of beer, toothpaste and many cosmetics. The same thickening property is used to make agar - a culture used in all laboratories around the world. Agar can also be eaten. Seaweed is widely used as a conditioner and mulch for soil and can be used to stabilise sand dunes. Farmers in Ireland have used seaweed for many hundreds of year as a mulch for soil. This soil was once just beach sand but with the help of the seaweed mulch has become rich farming soil.

Seaweed can also be used as a supplement in stock food and can be used to produce methane gas as an alternative energy source.

Some people believe that the clearing of seaweed from beaches and waterways is needed. However, many scientists think the seaweed washed up on beaches plays an important part in the whole ecology of the beach environment and that its removal could be harmful.

Back to The Sea links page.