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Approaches to Good Environmental Status (GES) for Man-Made Underwater Noise

This article discusses three different ways to approach achieving Good Environmental Status (GES) with respect to man-made underwater noise. It explores the use of pressure indicators, risk-based indicators, and impact indicators, highlighting their advantages and challenges.

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Approaches to Good Environmental Status (GES) for Man-Made Underwater Noise

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  1. Three different ways to approach Good Environmental Status (GES) with respect to man-made underwater noise Jakob Tougaard, Line Hermannsen, Jukka Pajala, Mathias Andersson, Thomas Folegot, Dominique Clorennec, Peter Sigray

  2. What is Good environmental status (GES)? GES must be managed throughindicators and targets Indicator Target Low High notGES GES

  3. Pressure indicators Pressure indicatorsmeasure the pressure (load) on the ecosystem Evaluate trends Hildebrand (2009) notGES • Underlyingassumption: lessnoisebetterthan more • Settingmeaningfultargetsverydifficult(zero is not a realistictarget) • What if we have GES, but do not know? -> overregulation ? (couldbe GES) GES or towards GES

  4. Impactindicators Impactindicatorsmeasure the impact (effect) on the ecosystem Quantifiesimpact Displacement Hearingloss Stress Excessmortality etc. • Allowpopulation basedtargets: • Noiseinducedexcessmortalitylessthan x% per year • Noiseinduced PTS not more than y dB in z% of population

  5. 1.Quantifying Pressure • 40 stations • 1 year of data • 25 Hz – 10 kHz • 33-100% dutycycle

  6. Percentiles – a first approach L75 ”Most of the time” L50 ”Half the time” L10 ”Occasionally” February 2014. 125 Hz third-octave band. Maximum in entirewater column.

  7. Weathergenerated vs. Ship noise notGES >2 ships/hour Day-time peaks due to ferry Slow variation: wind and waves GES Date

  8. Emergence: Ship noiseexceedswavegeneratednoise 125 Hz thirdoctave band, August Median emergence: shipnoiseexceedswavenoise 50% of the time notGES Emergence of shipnoise GES

  9. Emergence and GES Total noise (SPL) 90% Wavenoise (NL) GES Median 10% 125 Hz thirdoctavelevel (dB re 1 µPa) Almostnatural ambient Large ship component Completelyshipdominated not GES

  10. Dimensionless measure of masking Assumesconstant S/N for communication Sphericalspreading of comm. sounds R = 1 : nomasking R = 10 : comm. range red. to 1/10th 125 Hz, August 2014 Range reduction factor (Møhl 1981) Møhl, B. (1981). Masking effects of noise; their distribution in time and space. In N. M. Peterson (Ed.), The question of sound from icebreaker operations. Toronto: Arctic Pilot Project.

  11. GES by pressure - summary • Indicators readily available • Correlation with GES may be weak • Does not take animals into account • Very difficult to set targets • Aiming for decreasing trends may lead to overregulation • At the moment all we have – we must live with them for a while

  12. 2: Riskbasedindicators for GES G = risk factor Pressure Abundance Risk (G) = X 0 0 high GES Not GES high Advantage: Focus regulation on high-riskareas Disadvantage: no real measure of impact Caveat: Abundancemaybelowbecause of historicimpact!

  13. Porpoises and noise in the Baltic (summer) Midsjö banks Kadet Trench and the Sound ”SAMBIAS”

  14. 3: Impactbased approach to GES • Allowsmeaningfultargets on: • excessmortality • communication distances • hearingloss • Physiological stress • Somecanbemeasured, some not • Population level must be modelled • Targets rooted in management objectives Measureable Pressure Not measureable -> modelling

  15. Agent basedmodelling • Requiresreallygood input data • Must bebased on energeticvalues and costs • Still immature

  16. Conclusion 3: Impactindicators • Aim for population impact • Indicatorsdifficult todefine • Modelling of impactmayberequired 1: Pressure indicators • Indicatorsreadilyavailable • Correlation with GES maybeweak • Verydificult to set targets 2: Riskindicators • Same issues as for pressure • Allowspriotisation • Problematic if baseline levelsarenotGES Acknowledgements EU LIFE11 ENV/SE 841 Danish Nature Agency Swedish Nature Agency Ship crews and technicians biasproject.wordpress.com

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