Geoscience Reference
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Fig. 10.13 Swath-bathymetric image of a nearshore sand bank in the North Sea. The dark oval depressions mark the location of
individual monopiles, which are 4.2 m in diameter and 350 m apart, around which have developed scours up to 5 m deep and 50 m in
diameter. There are no scours or raised areas are continuous between adjacent monopiles and there is continuity of the crests of large
subaqueous dunes across the sandbank and near the monopiles. Thus in this case, the primary physical evidence indicates that the
monopiles appear to act individually on the sea-bed rather than in combination. (Image courtesy of EoN (Coventry), Andrews
(Great Yarmouth) and CEFAS.)
10.4
Other conventions are also relevant in a sedi-
mentary context, such as the United Nations
Convention on Biodiversity. As part of imple-
menting this convention, countries are required,
for example, to prepare Biodiversity Action Plans,
which involves some mapping of their continental
shelves (see e.g. http://www.jncc.gov.uk).
SHELF SEDIMENTARY SYSTEMS AND MANAGEMENT
10.4.1 National and international measures
There is a wide range of international and industry
measures aimed at protecting the marine envir-
onment. Some of the international agreements,
conventions and legislation apply to offshore
activities, some of which have relevance to
shelf sedimentary systems. Especially notable
is OSPAR, the Convention for the Protection
of the Marine Environment of the North East
Atlantic (www.ospar.org). OSPAR requires the
application of the precautionary principle, the
polluter-pays principle, best-available techniques
and best environmental practice, including the use
of clean technology. Three annexes to the Con-
vention relate to the prevention and elimination
of pollution from land-based sources, by dump-
ing or incineration and from offshore sources,
and two others relate to assessing the quality of
the marine environment, and protection and con-
servation of ecosystems and biological diversity.
10.4.2 Types of impacts on shelf habitats
Shelf sedimentary systems form the physical
structure for shelf habitats. This structure can
be impacted by:
1 Physical loss, for example by removal or
activities that may influence the sedimentary
regime and hence change the sea bed.
2 Physical damage, for example by dredging,
bottom trawling and extraction. Some habitats
may be more resilient and recover faster than
others, but extensive physical damage may lead
to loss of the original habitat.
3 Non-toxic contamination, such as by enrich-
ment by nutrients or organic matter. Physical
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