Fa. Meereszoologie, Nehmten HELCOM SUBMERGED 4 Tallinn, 12-14 April - - PowerPoint PPT Presentation

• Dipl. Biol. Sven Koschinski
• Fa. Meereszoologie, Nehmten

HELCOM SUBMERGED 4 Tallinn, 12-14 April 2016

„Darüber hinaus

Baltic Sea (Germany)

Thousands of mine and bomb explosions in WW1 and WW2 (Kiel Bight: ca. 3.000 explosions ), Intense combat

• perations also in the

Gulf of Riga, Irben Strait, and Gulf of Finland (Wichert 2014)

5 10 15 20 25 30 35 2007 2008 2009 2010 2011 2012 2015 "Kleinladung" (1-5 kg) Vernichtungssprengung Seeminen Bundeswehr Schönhagen

„Darüber hinaus

North Sea (Germany)

10 20 30 40 50 60 70 80 2012 2013 2014 2015 Vernichtungssprengung Seeminen

Increase of mine and bomb explosions in recent years due to offshore wind farm construction (cable laying and turbine installations)

MMS (2003): Explosive Removal of Offshore Structures, Information Synthesis Report, OCS Study MMS 2003-070, 181 pp.

Injury relevant noise parameters

• Peak pressure of noise impulse
• Rise time of noise impulse from

water pressure to maximum amplitude

• Maximum pressure variation
• Impulse duration
• Total energy content of the noise

impulse Very high peak pressure Extremely short signal rise time Maximum pressure variation Only short durations but total energy content impacts hearing Water saturated tissues behave just as water!

Foto: S. Dubpernel

Primary Blast Injury (PBI)

• heavy tissue damage

(especially gas filled organs : lung, seal ears, intestines)

• Internal bleeding (especially

brain and ears)

• damage and dislocation of

ear bones, tissue damage in inner ear (cochlea)

Photo: CSI, Woods Hole Oceanographic Institution

Acoustic trauma

• physiologic effect:

exhaustion of hearing sensory cells (TTS)

• damage of sensory

cells, nerve degeneration (PTS)

• High frequencies
• Low

frequencies

Cochlea with frequency selective basilar membrqane Hearing nerve Oval window Organ of balance

1000 2000 3000 4000 5000 6000 100 200 300 400 500 600 700 800 900 1000

Minimum distance in relation to charge weight

Example Tethered mine (300 kg)

Serious injury Thiele & Stepputat 1998: distancediver = 1500 * charge weight0,18 Charge weight(kg) Distance (m)

20 dB noise reduction by Neoprene hood Audiogram of a human diver

Increased danger close to the sea bottom!

• In the North Sea, harbour porpoises mainly feed on bottom-living fish species!

PBI (p ≥ 95%) PBI-Onset PTS-Onset TTS

SEL (dB) 1m below water surface 263 kg TNTeq. SEL (dB) 1m above bottom

aus: von Benda-Beckmann et al. 2015

• 88 UW-explosions in NL

2010-2011

• Charge weight 10-1000 kg

(most often 125-250kg)

• Noise measurements up to 2

km distance at various depths (7 detonations of 121 and 263 kg, water depth 26-28m, sand):

• Modeled source level (SEL)

relative to charge weight

• Propagation model improved

with noise measurements

• Analysis of effect radii and

harbour porpoise density (spring1.34, summer 0.6 Ind./km²)

Graph taken from: von Benda-Beckmann et al. 2015 (modified)

164 179 190 203 dB

Number of harbour porpoises (single explosion) Number of impacts (NL, 88

explosions per year)

Un- weighted threshold (SEL) All near surface All near bottom

Ø

All near surface All near bottom

Ø

Blast wave induced ear trauma very likely

203 dB 1 1 1 119 60

Permanent hearing loss very likely

190 dB 2 27 15 205 2.362 1.283

Permanent hearing loss increasingly likely

179 dB 18 106 62 1.584 9.318 5.451

Noise induced TTS very likely

164 dB 190 448 319 16.721 39.413 28.067

Data taken from : von Benda-Beckmann et al. 2015 (modified)

www.hydrotechnik-luebeck.de

r=70m Tethered mine: 350 kg

Air bubble curtain for shock wave reduction (20 m depth, Heidkate, Baltic Sea)

Air volume stream: 1m³/m*min

Schmidtke,E. Schockwellendämpfung mit einem Luftblasenschleier zum Schutz der Meeressäuger. (2010). DAGA conference 2010 Berlin, Germany

Big bubble curtain (BBC) for shock wave reduction

Pressure measured inside BBC In good agreement with literature data Pressure measured outside BBC All 3 mine explosions with BBC In mine 4 incomplete BBC reduction in peak pressure: 19 dB - 6 dB - 16 dB Noise propagation model -6,8 dB per doubling of distance: reduction in peak pressure results in reduction of injury radius by 86% - 46% - 80%, Noise propagation model -4,5 dB: 95% - 60% - 91%

Mitigation measure 1: deterrence by ~2 km

1

Number of harbour porpoises (single explosion)

Un- weighted threshold (SEL) All near surface All near bottom

Ø

Blast wave induced ear trauma very likely

203 dB 1 1

Permanent hearing loss very likely

190 dB 2 27 15

Permanent hearing loss increasingly likely

179 dB 18 106 62

Noise induced TTS very likely

164 dB 190 448 319

from: von Benda-Beckmann et al. 2015 (modified)

Mitigation measure 2: reduction of effect radii by ~ 80%

0,6 2,5 13

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Without mitigation

Assumption: animals are near bottom Blast wave induced ear trauma very likely Permanent hearing loss very likely Permanent hearing loss increasingly likely TTS very likely

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

100% deterrence up to 2 km

Blast wave induced ear trauma very likely Permanent hearing loss very likely Permanent hearing loss increasingly likely TTS very likely

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Blast wave induced ear trauma very likely Permanent hearing loss very likely Permanent hearing loss increasingly likely TTS very likely

100% deterrence up to 2 km + reduction of effect radii by 80%