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 |
| Synthetic compound contamination |
Uses: boats/shipping (anti-fouling) |
Low |
The toxic affects of tributyltin (TBT) on molluscs,
especially the dog whelk Nucella lapillus, are well-documented (Bryan et al.
1986, 1987). TBT was extensively used in antifouling paint specifically to kill marine
fouling organisms. Unsurprisingly, it therefore had a major ecological impact. Very low
concentrations of TBT can lead to the condition known as imposex (the development of male
sexual characteristics) in dog whelks. Dog whelks are an important predator on rocky
shores and their decline might be expected to have a profound effect on the rest of the
community. TBT also affects mussels, an important space-occupying species on rocky shores
and may therefore have important effects on community structure. |
Synthetic compound
contamination |
Uses: boats/shipping (oil spills) |
Low |
Modern dispersants have a low toxicity and are unlikely to do
any more harm than the oil. However, since the oil will become dispersed into the water it
may contaminate areas below the water level that were previously unaffected, unless it can
be trapped and removed. |
| Hydrocarbon contamination |
Uses: boats/shipping (oil spills) |
Intermediate |
The sensitivity of a rocky shoreline to oiling is dependent
on its topography and composition as well as its position. For example a vertical rock
wall on a wave exposed coast is likely to remain unoiled if an oil slick is held back by
the action of the reflected waves. Some shores are well known to act as natural collection
sites for litter and detached algae and oil is carried there in the same way. On exposed
coasts these sites are usually boulder/cobble beaches at the backs of bays or gullies
which act as traps for the oil. As on all types of shoreline, most of the oil is
concentrated along the high tide mark while the lower parts are often untouched. It is not
long before the waves and tides that carried the oil onto the shore are gradually removing
it again, but the rate of such weathering is dependent on weather conditions and shore
characteristics. On a shore exposed to strong wave action a patch of oil will usually not
remain there for long. |
| Changes in nutrient levels |
Waste: sewage discharge |
Not sensitive |
The effects of sewage discharge on high-energy rocky shores
are negligible. |
| Abrasion |
Recreation: popular beach/resort |
Intermediate |
The effect of people simply walking on the shore can be
damaging. This is particularly apparent when the topography of the shore causes people to
follow a limited number of routes, leading to the appearance of paths characterised by
reduced cover of fauna and flora (Fletcher 1997). Light trampling pressure has also been
shown to damage and remove barnacles (Bronsan & Crumrine, 1994). |
