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) |
Intermediate |
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 dispesants 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 un-oiled 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
moderately 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. |
| Changes in nutrient levels |
Waste: sewage discharge |
Low |
The effect of sewage discharge on a moderately exposed rocky
shore is low. Water movement limits the build up of particulates and prevents
eutrophication. |
| Abrasion |
Recreation: popular beach/resort |
Intermediate |
The recreational use of the shore can have adverse effects on
the biological community. 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). |
| Substratum change |
Coastal defence: seawalls/ breakwaters
Development: land claim |
Intermediate |
Natural shorelines are replaced with artificial substrata for
a variety of reasons. Colonisation of virgin artificial substrata and subsequent
succession is similar to that observed on natural substrata (Hawkins, Southward &
Barrett 1983; Cannon 1997). The time for a ‘mature’ community to develop is
therefore expected to depend on the scale of the development. |
