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Port and Harbour Operations
Potential issues, key processes & potential
impacts
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Considerations
and comments
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Potential impacts on marine SACs
Beneficial
Minimal
Adverse
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Possible means of avoiding, minimising and
addressing impacts
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Potential impacts from ship and boat movements.
The movement of ships to and from ports and
harbours can cause the following effects:
Issue: Ship and boat wash
Key process: Changes in physical regime
(waves & sediment transport)
Non-toxic contamination (sediment suspension)
Potential impact: Wash from ship and
boat movements may cause changes to the hydrodynamic
regime which may result in erosion of intertidal
and shallow subtidal habitats and disturbance
to communities.
Issue: Seabed disturbance by vessel movements
& propellers
Key process: Non-toxic contamination
(sediment suspension)
Potential impact: Boat and propeller
induced temporary increases in suspended solids
and turbidity may cause localised disturbance
of benthic animals and plants (Section
5).
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The effects are difficult to distinguish
from natural events or other human activities.
Impacts depend upon vessel size, type and
speed; level of activity, proximity to sensitive
intertidal and shallow subtidal habitats.
Effects depend on the types of vessel, level
of activity, sediment type and quality, water
depth and background suspended solid levels.
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Min/Adv
Min
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Education and codes of conduct for port and
harbour users.
Voluntary or byelaw enforced speed restrictions.
Zoning of activities likely to produce excessive
wash in relation to particularly sensitive
designated habitats.
Creation of sediment bunds or wave breaks
along the foreshore to protect important intertidal
habitats for which the site has been proposed
for designation.
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Issue: Collisions with marine mammals
Key process: Physical damage (collision)
Potential impact: Collisions with
high-speed vessels may cause the injury or
death of marine mammals.
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Collisions are rare in UK waters, but do
occur. This problem is more commonly associated
with high-speed recreational vessels. Limited
research on marine mammal strandings is ongoing,
but very little information is available relating
to ship/boat collisions.
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Min/Adv
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Education and codes of conduct for port and
harbour users.
Voluntary or byelaw enforced speed restrictions.
Zoning of seasonal ‘quiet areas’ in close
proximity to identified sensitive areas, such
as mammal breeding grounds and bird feeding
areas.
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Issue: Vessel noise
Key process: Non-physical disturbance
(noise)
Potential impact: Disturbance to marine
mammals and fish may occur from engine noise.
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Mainly a concern over disturbance to cetaceans
(dolphins and porpoises). There is some evidence
of noise disturbance to cetaceans from vessels.
Research is ongoing, but little information
is available relating specifically to noise
from ships/boats.
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Min
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Issue: Vessel groundings
Key process: Physical damage (abrasion,
siltation & smothering)
Potential impact: Grounding, due to
navigation error or accident, may result in
localised damage and disturbance to benthic
communities, re-suspension of sediments and
smothering.
Issue: Marine accidents or groundings with
loss of cargo or fuel
Key process: Physical damage (abrasion,
siltation & smothering)
Toxic contamination Non-toxic contamination
Potential impact: Marine accidents
or groundings resulting in releases of cargo
or fuel may cause a wide range of impacts
on habitats and species, including a deterioration
in water quality, contamination of sediments,
and smothering (see cargo handling below and
Section 6)
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Levels of disturbance will depend upon location
of incident, size of vessel, length of time
vessel is aground, and sensitivity of habitat
and communities affected.
The effects are highly specific depending
upon the type and quantities of cargoes/fuels
entering the marine environment, location
of incident, sensitivity of habitats and communities,
and, where appropriate, the effect of emergency
response.
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Min/Adv
Min/Adv
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Ensure safe navigation.
Emergency response planning (Section 6).
Use of pilots and effective VHF communications.
Zoning of activities – such as the creation
of ‘sole occupancy’ channels for large/ unmanoeuvrable
vessels, especially those carrying hazardous
or polluting cargoes.
Development of passage planning procedures.
The use of escort tugs for very large tankers
where it can be demonstrated as effective.
The introduction of modern VTS facilities
with digital signal processing and display
for busy harbours with dense traffic including
vessels carrying hazardous cargoes.
Re-routing of navigation channels where practical.
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Issue: Mooring and Anchoring
Key process: Physical damage (abrasion)
Non-physical disturbance (noise & visual
presence)
Potential impact: Anchoring vessels
may disturb or damage sensitive benthic communities,
in both rocky and soft substrates. The use
of permanent moorings may cause direct loss
of intertidal habitat and bird feeding areas,
some disturbance through noise and vessel
movements, particularly adjacent to areas
used by birds.
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Disturbance from anchoring depends upon the
frequency, magnitude and location of activity,
type of sediments, and the sensitivity of
benthic communities.
Where the bottom sediments are soft and there
are no sensitive communities, less impact
is likely to be caused. The impacts arising
from mooring vessels depend on the type of
mooring used.
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Min/Adv
Min
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Education, information and codes of conduct
for port and harbour users, indicating areas
where anchorage will cause no harm and discouraging
anchoring in areas where there are important
subtidal animals and plants.
Voluntary or byelaw enforced anchorage restrictions.
Zoning of seasonal ‘quiet areas’ in close
proximity to identified sensitive areas, such
as mammal breeding grounds and bird feeding
areas.
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