Kelp beds and forests
What is it?
Kelp is the name given to several species of large brown seaweed. It has a similar structure to a plant, with a branching holdfast that roots it to the seabed, a thin hard stalk (called a stipe) and fronds that spread out like leaves.
Where conditions are right, kelp can form dense underwater forests, which are among the most productive and diverse ecosystems on the planet!
Kelp forests play a hugely important role in the carbon cycle of our planet, capturing 75% of the net carbon fixed annually in the sea.
Why is it like this?
Like plants, kelp depends on sunlight for survival. This means that they will only grow in shallow water where sunlight can reach the seabed - from the low tide mark down to 45m if the water is clear.
Kelp forests grow on hard, rocky surfaces where they can tangle their root-like holdfasts around the stone.
The leaf-like fronds contain air-filled bladders that help the kelp stalks float upright in the water, giving kelp beds the drifting appearance of an underwater forest.
Distribution in the UK
Kelp can be found all around the coasts of the UK, with forests developing in areas with a suitably rocky seabed.
The species of kelp varies depending on how exposed the coast is to wave action. Very exposed coasts have lots of winged kelp (Alaria esculenta), less exposed areas hold tangle weed (Laminaria digitata) and cuvie (Laminaria hyperborea), whilst sheltered coasts are dominated by sugar kelp (Laminaria saccharina).
The UK has the most diverse community of kelp species compared to any other country in Europe, with 7 out of the 14 species found across Europe.
What to look for
The holdfast at the kelp's base forms a network of nooks and crannies, providing a home for hundreds of individual animals. Worms and crustaceans burrow into the gaps, anemones and sea squirts cling to its surface, and small fish use it for shelter. Larger fish, like lumpsuckers, often lay their eggs amongst the holdfasts.
Smaller seaweeds cling to the rough surface of the stipe, sheltering other wildlife, whilst the fronds support colonial animals like sponges, sea mats and red seaweeds.
The thick, floating forest of kelp provides food and shelter for juvenile fish, which in turn attract larger fish and other predators like grey seals.
Kelp only grows in the cool temperate and polar regions of the planet; global warming could change the distribution of kelp forests, or make the water too warm for them to survive. Losing our kelp forests would cause a ripple effect, impacting the many species that depend on them.
The Wildlife Trusts are calling for more Marine Conservation Zones to be designated in UK waters, protecting special habitats at sea. You can help by pledging your support and becoming a Friend of MCZs.