SILENT MEADOWS: Assessing Underwater Noise Impacts on Seagrass Ecosystems and Associated Fauna in European Seas

Background & Rationale: Anthropogenic underwater noise from shipping, construction, and recreational activities is a pervasive but poorly understood pollutant in coastal waters. While research has focused on charismatic megafauna (cetaceans, fish), impacts on coastal vegetated ecosystems and their associated communities remain virtually unknown. Seagrass meadows are critical nursery habitats where soundscapes mediate larval settlement, fish communication, and predator-prey dynamics. Yet no systematic assessment exists of how noise pollution affects seagrass ecosystem function. This knowledge gap hinders effective implementation of the EU Marine Strategy Framework Directive's noise indicators.

Objectives: SILENT MEADOWS will: (1) characterize soundscapes across European seagrass meadows spanning noise gradients; (2) assess behavioural and physiological responses of seagrass-associated fish and invertebrates to noise exposure; (3) evaluate whether depth refugia also function as acoustic refugia; (4) quantify cumulative impacts of noise combined with thermal stress and habitat degradation; and (5) develop noise exposure thresholds and management recommendations for seagrass ecosystems.

Approach: We will deploy passive acoustic monitoring arrays in seagrass meadows across 8 sites representing diverse noise environments: busy shipping lanes (Greece, Israel), port approaches (Netherlands, Spain), construction zones (Germany), and quiet reference sites (Croatia, Portugal, France). Continuous soundscape recordings will be paired with ecological surveys of fish assemblages, invertebrate communities, and seagrass condition. Controlled exposure experiments will test behavioral responses (feeding, movement, predator avoidance) and physiological stress markers. Our existing long-term monitoring data will enable assessment of cumulative impacts where noise coincides with marine heatwaves and other stressors.

Expected Outcomes:

• First pan-European seagrass soundscape database

• Noise exposure-response curves for key seagrass fauna

• Depth refugia assessment as acoustic refugia

• Recommended noise thresholds for seagrass MPAs

• Guidelines for MSFD Descriptor 11 (underwater noise) in coastal habitats

• Mitigation recommendations for shipping and coastal development

Partners Sought:

• Underwater acoustics specialists

• Fish ecologists and behavioral biologists

• Passive acoustic monitoring technology providers

• Port authorities and shipping industry

• MSFD implementation bodies

• Environmental impact assessment consultancies

Countries: Israel, Greece, Netherlands, Spain, Germany, Croatia, Portugal, France (8 countries)