Biodiversity & Conservation

Kelps provide a substratum for a large number of epiphytic flora and fauna (see Ecological relationships and Habitat complexity) and it has been estimated that the rugose stipes provide one and a half times that surface area provided by the bedrock (Jones et al. 2000). Holdfasts support a diverse fauna that represents a sample of the surrounding mobile fauna and crevice dwelling organisms, e.g., polychaetes, small crabs, gastropods, bivalves, and amphipods. The kelp beds provide refuge for nurseries, reduce current flow and ameliorate wave exposure, allowing more delicate organisms to survive in the shallow sublittoral. Shading by the canopy allows shade tolerance algae, especially Rhodophyceae to extend into the upper infralittoral. Kelps beds are an important primary producer of organic carbon for surrounding communities (Birkett et al. 1998b). Humans also harvest kelp directly or benefit from the fisheries or shellfisheries that they support.

Kelps have been harvested for the alginate industry which produces valuable emulsifiers and gelling agents for cosmetic, pharmaceutical and food industry. Laminaria hyperborea is harvested commercially in Norway, Brittany, Scotland and Ireland. Wilkinson (1995) reviewed the effects of kelp harvesting. He suggested that extensive shallow kelp beds absorb wave energy, acting as natural coastal defence in some areas and that harvesting should be restricted in theses locations. Echinus esculentus is an important structuring species and is collected commercially but not in numbers that would adversely affect the biotope. It was the object of a specific fishery in Cornwall in the 1980s. Nichols (1981) pointed out that although most divers missed small specimens within kelp beds, population densities should not be allowed to fall below 0.2 per metre to conserve the species in the UK. The possibility of a sea urchin fishery in Shetland for the Japanese market has been investigated recently (Penfold et al. 1996).

Kelps are the major primary producers in UK marine coastal waters producing nearly 75 percent of the net carbon fixed annually on the shoreline on the coastal euphotic zone (Birkett et al. 1998b).