Sensitivity to human activities

Activities listed are those which influence, or are likely to influence this habitat and which are assessed in the UK marine SAC project review. The sensitivity rank may require amendment in the light of new information becoming available.

Sensitivity to: Human activity Rank Comments
Change in temperature Climate change/global warming


This would affect the biogeographical distribution of kelp according to their temperature tolerances. Unfortunately, global warming effects span multiple generations of scientists and governments and the need for very long term monitoring research has only recently been appreciated.
Hydrocarbon contamination Uses:

boats/shipping (oil spills)


The mucilaginous slime covering kelps is thought to act as a protective device (O’Brien & Dixon 1976). Laminaria digitata showed reduced photosynthetic rates when emersed in crude oil (Schramm 1972). Laminaria hyperborea however would probably not come into contact with freshly released crude oil because of its continual emersion.
Removal of target species Collecting: kelp/wrack harvesting


Svendensen (1972) examined kelp beds over periods of up to 3 years after harvesting and found the Laminaria population to be dense after one year. He regarded the beds as completely regenerated in terms of biomass after 3-4 years. Sivertsen (1991) compared the regrowth of kelp in areas trawled 1-5 years previously with areas freshly trawled and also control areas. Large canopy-forming plants were absent until 4 years after harvesting, but the structure of the kelp population was beginning to stabilise with little change in plant density from years 4-5. A further interesting observation was the replacement (for one year only) of the L. hyperborea-dominated forest with a population of S. polyschides as in the clearance experiments by Kain (1975). Harvesting may also affect those species associated with the kelp biotope. Rinde et al. (1992) carried out a survey to establish the affects of kelp harvesting on common organisms within the kelp biotope. They found the forest structure to recover to almost normal after 3-4 years, but argued that the forest did not provide the same physical environment for the other organisms which it shelters. The dredged areas tended to have growth of other kelps on the bottom, e.g. Alaria esculenta, while the bottom between the young L. hyperborea plants was uniformly covered with coralline algae after 3 years. In the control areas there was a more diverse bottom community.
Removal of non-target species Collecting: shellfish (winkles, mussels) Intermediate The removal of predators such as lobsters and crayfish could result in an unchecked urchin population, which could in turn destroy kelp populations and form ‘urchin barrens’.

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