What are kelp?
Kelp are flat-bladed, large brown seaweeds mostly found around rocky shores. They often grow in dense beds, creating some of the most biodiverse marine environments on the planet. Kelp can be thought of as 'marine trees' anchored to the seabed that create a 'canopy' under which many species take shelter and find food.
As well as improving biodiversity, kelp provide a myriad of other ecosystem services (the benefits that healthy, functioning ecosystems generate) for nature, people and planet.
The SKRP focuses on four historically common kelp species of Sussex:
Oarweed (Laminaria digitata),
Tangle (Laminaria hyperborea),
Sugar Kelp (Saccharina latissima)
Furbellows (Saccorhiza polyschides). (Furbellows is not a true kelp, but is often considered a pseudokelp due to similar appearance and ecology.)
While occasionally exposed at low tides, most kelp are permanently under the sea (otherwise known as subtidal). All kelp have a claw-like 'holdfast' to attach to rocks, pebbles and artificial structures. They are vulnerable to becoming detached during storms and are often found washed up on beaches.
Kelp starts its life as a free-floating microscopic organism called the 'gametophyte'. The kelp we see growing on the seabed is a 'sporophyte', and this is the final phase in its multi-staged life cycle. All young sporophytes develop a simple blade (not a leaf) and it's difficult to tell young species apart. They either continue to grow into a single large blade (which is what Sugar Kelp do) or develop a longer stipe (stem) and a wider blade to create the familiar 'trident' form where the blade splits into multiple fronds or ‘digits’, as is the case for Oarweed, Tangle and Furbellows.
Some kelp are perennial and can live for over two decades (Oarweed and Tangle). In contrast, Furbellows is an annual species living for just one year, while Sugar Kelp can be annual but often lives for two or three years.