BSEP116B Biodiversity in the Baltic Sea - Helcom

Communication links
There are a number of communication links (mainly
bridges) connecting cities and/or countries in the
Baltic Sea. One of the major projects finalized
during recent decades is the communication link
between Denmark and Sweden (bridge combined
with tunnel and an artificial island) (Figure 6.3.1,
left). Other large-scale construction projects
include the Öland Bridge, the Great Belt Fixed Link,
and the St. Petersburg flood barrier and communication
link (Figure 6.3.1, right). Currently, a plan to
build the world’s longest bridge from Germany to
Denmark over the Fehrman Belt marine protected
area has been adopted by the Danish and German
governments.
current lines (HVDC) (Figure 6.3.2, left). The
most recent cable connection is the ‘SwePol Link’
(230 km, 450 kV). In addition to power cables,
there are several existing and planned communication
cables across the southern sea basins.
The underwater power transmission lines cause
mechanical damage to the seafloor (during cable
laying), the release of toxic chlorine during electrolysis
(in one cable solution), and are the source
of an electromagnetic field that may possibly influence
migrating fish. However, the relative impact
of power cables on Baltic Sea biodiversity is probably
low (Andrulewicz et al. 2003).
Environmental concerns associated with the construction
of communication links are usually related
to mechanical damage of the sea bottom and the
release of sediment plumes during the construction
phase; i.e., they cause the same effects as dredging,
as described above. After construction, bridges may
affect the water exchange. The underwater parts of
bridges also introduce a new habitat that provides
good attachment sites for sessile organisms (Elsam
Engineering & ENERGI E2 2005).
Oil and gas exploitation platforms
Oil in the Baltic Sea is extracted by two oil platforms:
’Petrobaltic’ in the Polish Exclusive Economic Zone
(EEZ), and ‘D-6’ in the Russian sector of Kaliningrad
Oblast (started in 2006). The operation of these oil
platforms has not been observed to cause any significant
environmental problems. However, oil and
gas extraction activities may increase in the Baltic
Sea and therefore may be recognized as a potential
environmental concern (for impact, see Chapter 6.2,
Maritime activities).
Power and communication cables
Power cables have a long history in the Baltic; one
of the first cables in the world was the ‘Gotland’,
which connects the island of Gotland with the
Swedish mainland. The present cable network in
the Baltic Sea consists of nine high-voltage direct
Ports, oil terminals and piers
Ports, oil terminals and piers have been constructed
in many places along the Baltic Sea coast. The
annual throughput of the 51 member ports of the
Baltic Ports Organization (BPO) is 400 million tonnes
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Figure 6.3.1. Left: ‘Öresund Link’ connecting Denmark and Sweden. Right: satellite image of the St. Petersburg flood barrier
and a by-pass road off St. Petersburg (under construction) (picture based on the www portal http://maps.google.com).