WODA Technical Guidance on Underwater Sound from Dredging

Abstract

The World Organization of Dredging Associations (WODA) has identified underwater sound as an environmental issue that needs further consideration. A WODA Expert Group on Underwater Sound (WEGUS) prepared a guidance paper in 2013 on dredging sound, including a summary of potential impacts on aquatic biota and advice on underwater sound monitoring procedures. The paper follows a risk-based approach and provides guidance for standardization of acoustic terminology and methods for data collection and analysis. Furthermore, the literature on dredging-related sounds and the effects of dredging sounds on marine life is surveyed and guidance on the management of dredging-related sound risks is provided.

Evaluating effects of dredging-induced underwater sound on aquatic species : a literature review

“…Techniques for mitigating underwater sound can be informed by a riskbased approach (Boyd et al 2008;Thomsen et al 2016). For simplicity, mitigation strategies that can alter the risks associated with underwater sound can be categorized into avoidance and minimization techniques.…”

“…Additionally, the intent was to include literature that reported biological responses to sound that spans from sub-lethal to lethal responses, in efforts to provide context for potential risks associated with the acoustical characteristics of dredging. It should be noted that there should be caution when directly comparing across studies, due to the lack of standardized underwater sound measurement techniques and methods for measuring biological responses (Thomsen et al 2016;Erbe et al 2016).…”

“…A key principle to understanding and predicting adverse effects from underwater sound is to develop exposure-response relationships of underwater sound for environmentally relevant organisms (Boyd et al 2008;Thomsen et al 2016). Reported effects to marine biota following exposures to anthropogenic sounds (e.g., pile driving, sonar, and shipping) range from lethal to sub-lethal (behavioral effects).…”

“…In terms of mammal responses to dredging-induced sounds, there are limited data directly measuring the onset of auditory injury. Based on the data available for mammal responses to other anthropogenic underwater sounds, risks associated with dredging are likely limited to masking and behavioral effects (Thomsen et al 2016). Only a single study to date has estimated the onset of PTS and TTS from dredging sounds (Heinis et al 2013).…”

“…Accurate characterization of the acoustic exposure and biological responses is a critical step preceding risk management. A risk-based approach provides a systematic framework for characterizing exposures and biological responses to inform actions such as mitigation (Boyd et al 2008;Thomsen et al 2016;Merchant et al 2017). A critical aspect of any successful underwater sound risk framework is to identify and mitigate appropriate ecological risks and to avoid managing ecologically insignificant risks that would pose unnecessary constraints and costs on dredging operations.…”