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S 78 ‘Ozelot’ fast attack craft at full speed (© 2006 German Bundeswehr/PIZ Marine)
S 78 ‘Ozelot’ fast attack craft at full speed (© 2006 German Bundeswehr/PIZ Marine)

The precise impact of military activities on the marine environment is very hard to assess, partly because access to information on the nature and scale of such activities is severely restricted.

Military activities in the North Sea and Baltic Sea

Military manoeuvres in the North Sea and Baltic Sea take place in the air (such as low flying exercises), on water (such as firing exercises) and underwater (such as submarine manoevres). First of all, there is the disturbance from naval traffic. To this is added noise from fighter aircraft, exercise firings and explosions (in some cases with noise levels over 250 dB), plus cumulative noise from large naval formations. Exercises near protected areas especially can have a severe impact on fauna inside them.

Heavy naval traffic and surface noise from firing exercises can also scare and drive away resting or moulting seabirds.


U 34 submarine in Kiel Bay (© 2007 German Bundeswehr/Ricarda Schönbrodt)
U 34 submarine in Kiel Bay (© 2007 German Bundeswehr/Ricarda Schönbrodt)

Submarine noise, generated among other things by military high-performance active sonar (including low-frequency sonar to detect submarines) can cause severe or even fatal injury to marine mammals like harbour porpoise and seals. Low-frequency sonar (LFS) produces underwater sound pulses with an intensity of 235 dB in the middle and low frequency range used by whales, porpoises and dolphins. Low-frequency sound waves can propagate several thousand kilometres, considerably increasing the disturbance radius of sonar systems. Communication systems, too, emit underwater sound waves with intensities of 180-200 dB.

The impacts of sonar in particular on marine mammals range from habitat loss to scaring away and even death. For more on noise impacts, see Impacts of underwater noise.

Ongoing military activities are not the sole source of military impacts on the marine environment. Long-forgotten explosive ordnance still lies untouched on the bottom of North Sea and Baltic Sea. Current estimates put this at some 1.6 million tonnes of munition. The main problems for the marine environment are detonation on contact and the release of pollution.

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