Kelp - Its Role is Marine Ecosystems

Points covered:

• What is kelp?
• How does kelp grow?
• What feeds on kelp?
• Why is kelp important to temperate marine ecosystems?

Words to know:

• MACRO-ALGAE - multicellular algae or seaweed.
• TEMPERATE - cool, as opposed to tropical waters, which are warm.

Kelp are seaweeds that grow on the sea floor where light can penetrate.They are the largest seaweeds, with some species growing up to 30 metres in length. Kelp are classified as a brown algae (Phaeophyta), and are one of the three main groups of seaweeds. There are more than 1200 native species of macro-algae in the temperate waters of Australia, but only four of these species are kelp. However, kelp are very abundant.

Kelp usually grow in forests which are highly productive ecological systems, comparable to tropical rainforests. Like rainforests, they form canopies under which many other species live including algae, fish, snails, shrimps and sponges.

Kelp forests also provide food for a wide range of marine organisms, including many fish and other commercially important species, such as abalone. While kelp is a source of food for many organisms which live in and around kelp forests, once it dies and decays, it becomes an important source of food for many animals at all levels of coastal marine ecosystems.

Kelp are one of the few groups of organisms that completely change the habitat they live in, transforming a two-dimensional rocky surface, to a complex three-dimensional environment. In this way, kelp have a profound effect on the ecology of rocky reefs.

Kelp forests are a common sight below the water on temperate Australian coastlines and, along with other macro-algae, they are essential for maintaining the biodiversity of temperate coasts.

Peter Steinberg
Centre for Marine Science
University of New South Wales