The underwater sound levels of Lithuanian marine harbour.

Aquatic animals rely on sound to communicate, navigate, prey, or avoid predation in turbid waters. The acoustic environment of their habitats plays an important role in their life, i.e. the fishes understand the environment using sound. Documented studies provide data indicating that marine habitats can be altered by anthropogenic noise, due to which marine life can be affected. The nearshore and the areas of harbours are usually predominated by the high sound pressure levels of anthropogenic origin resulting from frequent passages of pleasure vessels and other kind of ships nearby. These high levels no doubt can cause the risk of negative effects on marine life inhabited or migrating through nearshore and harbour areas. With the aim to assess the underwater sound levels at Klaipėda harbour area, underwater acoustic measurements were implemented. The obtained results indicate that the Klaipeda harbour is affected by the anthropogenic underwater noise and long-term noise monitoring may be useful to assess the trends of prevailing underwater noise in this area. In this paper, the results of the continuous underwater sound level measurements along with the analysis of the influence of anthropogenic sources and environmental factors on prevailing soundscape are presented; the risks of negative effects of elevated underwater noise levels on fish species and possible underwater noise measures are shortly discussed.