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  • Writer's pictureAna Štrbenac

Underwater anthropogenic noise threatens the life in our seas – what to do about it?

Updated: Feb 12, 2018

Marine wildlife has faced a new threat in the last decades: underwater anthropogenic noise. This noise is result of various human activities such as maritime traffic, military exercises, seismic surveys or coastal and offshore projects.

Where is a problem?

The sound travels in the sea more than 4 times faster than in the air. This feature is used by many marine organisms. Hence, the sound represents a mean of communication, foraging, exploring environment and other life activities. However, the noise produced by man has similar frequencies as sound produced by animals. As a consequence, the anthropogenic noise may have negative effects on marine wildlife such as causing physical damage, behavioral changes, chronic/cumulative impacts and stress. Anthropogenic noise has also economic implications: it has been recorded that fish catch is decreased up to 50%. More recently, negative effects on zooplankton have been proved.

What to do about it?

In recent years, the south-eastern European part of the Mediterranean Sea - SEE Med Region has been an area of intensive seismic surveys for oil and gas. At the same time, this region, as well as the entire Mediterranean Sea, represents one of the biodiversity hotspots. For example, this SEE Med Region contains critical habitats of monk seal, sea turtles and certain dolphin species. A special workshop on Mitigating the impact of underwater noise on marine biodiversity with specific focus on seismic surveys in the south eastern European waters in the Mediterranean Sea took place November 22-23, 2017 in Split, Croatia. This event was organised and hosted by OceanCare and NRDC, international nature conservation organisations, and was technically and financially supported by the Deutsche Bundesstiftung Umwelt (DBU). The workshop was attended by 65 participants from 15 countries, representing various stakeholder groups; governmental institutions, such as ministries, nature protection, conservation, and energy agencies; international organizations, including multilateral, regional, environmental agreements and regional fisheries bodies; European Commission; scientists and civil society organisations. This was an opportunity to present and discuss various aspects of the underwater anthropogenic noise issue.

Regional situation has been analysed and compiled in the Overview of underwater anthropogenic noise, impacts on marine biodiversity and mitigation measures in the south-eastern European part of the Mediterranean, focusing on seismic surveys. This report also includes overview of future seismic activities.

Figure. Planned seismic surveys (licensed, under the application) in the wider SEE Med Region, presumably until 2020. Extracted from Štrbenac, 2017. for OceanCare

One of the most relevant recent contribution to the anthropogenic noise mitigation are the CMS Family Guidelines on Environmental Impact Assessment for Marine Noise-generating Activities, adopted by CMS parties as a part of the specific resolution at the 12th Conference of Parties (COP 12) in October 2017. The Guidelines provide advice to decision-makers to assess negative impacts of anthropogenic noise from various sources before approvals to proceed are granted. The emphasis has been put on expert arguments and transparent consultation process.

In addition, new technology has been presented, so called Marine vibroseis. This is a quieter option to seismic airguns, sparing particularly the high-frequency hearing cetaceans such as beaked whales and dolphins.

What can be done to mitigate underwater anthropogenic noise as much as possible in the SEE Med Region and beyond?

The workshop’s participants have agreed on 16 recommendations, which will be further shared with the international community and all stakeholders who may contribute to their actual implementation.

These recommendation emphasise in particular:

  • Need for precautionary principle:

  • Exploration of the concept of the noise budget /threshold ;

  • Addressing the cumulative effects;

  • Improvement of quality of environmental impact assessments through implementation of the CMS Guidelines;

  • Definition and implementation of Best Available Technologies and Best Environmental Practices to mitigate impacts of anthropogenic noise;

  • Further development and mandate the use of best-available quieting technologies;

  • Removing subsidies for the oil and gas industry and spend public money in line with the objectives of the 2015 Paris Agreement on Climate Change;

  • Improvement of knowledge about most sensitive species;

  • Exchange of knowledge and experience and improvement of cooperation between various stakeholders.


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