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 Klaipeda 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.

Wind energy development and wildlife conservation in Lithuania: A mapping tool for conflict assessment.

The paper presents a mapping tool aiming to identify and minimise potential conflicts between onshore wind energy development and wildlife conservation in Lithuania. It merges current information on the distribution, conservation status and sensitivity of birds and bats to wind power with an integrated evaluation of wind resources (modelled wind speed), special planning status and technical perspectives of wind energy development. The paper includes assessment of the selected wildlife species which were described as sensitive to wind power (69 breeding and 43 migratory bird species and 17 bat species bats in the country). Used species level information allowed the precise identification of sensitive territories and might be used to mitigate negative wind farm effects using special measures based on species behavior. Finally, we delivered overlaps as possible conflicts among the most promising wind farm areas and the areas with high sensitivity in relation to bird and bat distribution. These overlaps point to the required attention and relevant decisions that are needed to ensure sustainable development of wind energy throughout the country. We suggest this tool for initial determination of appropriate areas for wind energy development in the country and as supplement to Environmental Impact Assessment.

Underwater noise level predictions of ammunition explosions in the shallow area of Lithuanian Baltic Sea.

Among the noisiest man-made activities in the seas, emitting very high acoustic energy are the underwater explosions of various objects and ship shock trials. Sound energy emitted by high explosives can be predicted or measured at sea. Sometimes, it can be convenient to apply empirical formulas and scaling laws to approximate the energy of underwater explosions. In addition, at some instances the determination of the spectral properties of the explosions is useful, i.e. when possible animal exposure to impulsive noise has to be evaluated. This paper presents an example of an application of freely available scaling laws and equations for prediction of noise levels of underwater explosions of historical ordnance in the shallow sea environments. Main findings of the study: An available scaling laws applied to model underwater explosion properties; spatial extent of explosion mapped; arising issues of modelling of underwater explosions in the shallow marine areas discussed.

A comparison of impact and risk assessment methods based on the IMO Guidelines and EU invasive alien species risk assessment frameworks.

A comparative analysis of two risk assessment (RA) frameworks developed to support the implementation of the international Ballast Water Management Convention (BWMC) and European Regulation on Invasive Alien Species (IAS) was performed. This analysis revealed both differences and similarities between the IMO Risk Assessment Guidelines (IMO, 2007) and EU Regulation supplement on RA of IAS (EU, 2018) in RA approaches, key principles, RA components and categories of IAS impacts recommended for assessment. The results of this analysis were used to produce a common procedure for the evaluation of the bioinvasion risk and impact assessment methods intended to support international, regional and/or national policy on IAS. The procedure includes a scoring scheme to assess compliance with the key principles, RA components and categories of bioinvasion impacts taken into account by the methods. In these methods the categories of impacts on human health and economy are underrepresented comparing with impacts on environment.

Method for the simplistic modelling of the acoustic footprint of the vessels in the shallow marine area.

The definitions of the 11th descriptor of the EU Marine Strategy Framework Directive (MSFD) "Underwater noise and other forms of energy" outlines the standards for the continuous noise evaluation and monitoring in the European seas. Long lasting fluctuations of the continuous underwater noise at the shallow marine areas in the low frequency bands (<1 kHz) are mostly associated with the shipping noise, where these fluctuations are sensitive to changes in the spatial distribution of human activities, or changes of environmental and climatic variables. Underwater noise modelling is usually considered as a supplement to noise measurements, where models increases the utility of the measurement results. Noise mapping is considered as a form of spatial modelling, providing a convenient and accessible way to visualise models. Therefore, underwater noise models and maps can be used in management and evaluation of environmental state. There are number of freely available widely used noise source and sound propagation models. Still the simplistic logarithmic rules purposed for the sound propagation loss computations do not account for the number of factors in the marine environment, i.e. sediment type, water depth or frequency. On the other hand the sophisticated physical models purposed for the description of the footprint of noise sources such as ships are complex and their programing requires very specific knowledge. In this paper the details of the method purposed for modelling of the ship noise footprint in shallow seas is presented. Proposed method allows to compute: •depth dependent ship sound transmission losses in 1 Hz frequency bands;•sound propagation losses during different seasons (summer/winter);•acoustic footprint accounting for vessel noise directivity.