IVL Swedish Environmental Research Institute is one of the scientific partners in DEMASK. With expertise in both underwater acoustics and marine ecology, IVL connects noise measurements to real impacts on marine species. Their work involves two parts of the project: work package 2 (noise) and work package 3 (marine life). We spoke with Torbjörn Johansson, team leader for acoustics, and Anna-Sara Krång, senior researcher in marine ecology/ecotoxicology, to learn more about their contributions and insights from the project so far.
IVL’s role in DEMASK
IVL works across many areas of sustainability, from pollutants and air quality to policy development and environmental technology. Underwater noise is one of the newer research areas in the institute. “Noise is recognised as a pollutant by the EU and the UN,” Torbjörn explains. “So, we work with it in the same way as other pollutants: we measure it, understand how it spreads and affects the marine environment, and explore how it can be reduced.” Over the past years, IVL developed a dedicated underwater acoustics team that now contributes to several national and European research projects, including DEMASK.
Mapping recreational boating noise (work package 2)
In work package 2, DEMASK partners create underwater noise maps for different sound sources. IVL works specifically on recreational boating noise, a sound source common in shallow coastal waters but still poorly understood. “Our part of the project is to develop a noise map for a marine protected area in Sweden,” says Torbjörn. “As far as we know, it may become the world’s first detailed underwater noise map for recreational boating.” The study area contains around 750 small islands, strong depth variations, and high biodiversity, making it both environmentally relevant and scientifically challenging.
Torbjörn and Anna-Sara during their field work.
Developing new methods
Because little data exists on recreational boat noise, IVL needed to design a new approach. Their work combines two months of continuous underwater noise recordings at multiple sites, propagation measurements using an underwater loudspeaker, and boat noise measurements to estimate how different vessels radiate noise at different speeds. One finding was that noise levels rise as boats increase their speed, but only up to a point; after a certain speed, noise levels stay relatively constant. These insights feed into DEMASK’s broader work on future noise scenarios and the effectiveness of measures such as speed limits or no-go zones. “The final maps will help local authorities understand how much noise there is and what measures may reduce it most effectively,” Torbjörn says. The noise maps were recently validated by comparing to the recordings. The results were positive, showing that the new methods developed for the DEMASK project work. “We were surprised that the noise map agreed so well with the results we got from the recordings. There were differences in some places, and we were able to understand why and identify how our methods can be improved in the future”, says Torbjörn.
Assessing impacts on invertebrates (work package 3)
While work package 2 focuses on noise levels, work package 3 looks at how this noise affects marine life, including mammals, fish, and invertebrates. Anna-Sara Krång from IVL leads the work on invertebrates within DEMASK. “Invertebrates make up most marine species and have very important roles in the ecosystem,” she explains. “But they are often overlooked in underwater noise assessments because of limited data.”
A trait-based framework for vulnerability
To address this gap, IVL and partners have created a trait-based vulnerability assessment framework: a method that looks at the key biological traits of each species to understand how sensitive it is to underwater noise. The framework considers how species detect sound, documented impacts on for example behaviour and stress, life-history traits such as mobility and population turnover, the ecological and commercial importance of each species, and the quality of available scientific data. Using this approach, the team has identified around five indicator species for invertebrates in the North Sea, including well-studied species such as lobsters, mussels and cephalopods. The work has already been presented at the Aquatic Noise Conference and will soon be published in a scientific paper.
Bringing noise maps and species vulnerability together
The final year of DEMASK will focus on combining results from all work packages. Noise maps from work package 2 show where and how much sound is present, today and in future policy scenarios developed in work package 1, while vulnerability assessments from work package 3 show which species are sensitive and where they live. This will result in ecosystem-based risk maps for the North Sea. For invertebrates, IVL is now mapping species habitats, gathering distribution data, and identifying possible noise limit values, a complex but important next step. “To do a comprehensive assessment, it is essential to include invertebrates,” Anna-Sara says. “They constitute the majority of all marine species and are an essential food source to many other species.”
Collaboration and looking ahead
Both researchers highlight the value of working with DEMASK partners and the strong, open exchange within the consortium. The final project period will focus on testing management scenarios, comparing maps with other partners, and finalising risk assessments for invertebrates. Both Torbjörn and Anna-Sara hope the methods developed in DEMASK will be used in other regions in the future. They describe being part of DEMASK as rewarding, meaningful, and an important step for IVL’s underwater noise research.
About IVL Swedish Environmental Research Institute:
IVL is an independent and non-profit research institute with a broad environmental profile. IVL combines applied research and development with a close collaboration between the business and public sectors and works actively across the entire area of sustainability. Main areas are sustainable environment, society and transition, with expertise in environmental sciences, as well as behavioural and social sciences and economics.|
Pictures taken by Anna-Sara Krång