Clare Embling 2015 Seals & Shipping Noise
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Chen F., Shapiro G., Bennett K.A., Ingram S.N., Thompson D., Vincent C., Russell D., Embling C.B. f [email protected] [email protected] @ClareEmbling @MarineVerts Seals and shipping noise in a dynamic sea: seasonal changes in shipping noise exposure experienced by diving seals
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Seals and shipping noise in a dynamic sea: seasonal changes in shipping noise exposure experienced by diving sealsChen, F.1, Shapiro, G.1, Bennett, K.1, Ingram, S.N.1, Thompson, D.2, Vincent, C.3, Russell, D.2, & Embling, C.B.11. School of Marine Science and Engineering, Plymouth University, Plymouth, PL4 8AA2. Sea Mammal Research Unit, University of St Andrews, St Andrews, Fife, KY16 8LB3. Université de La Rochelle, Avenue Michel Crepeau, 17042 La Rochelle Cedex, FranceEmail: [email protected] noise is a major contributor to anthropogenic noise in the sea, which is now classed as pollution in accordance with the Marine Strategy Framework Directive (MSFD). However, we know little about how it impacts marine organisms. In this study we investigate potential shipping noise experienced by grey seals (Halichoerus grypus) in the Celtic Sea by overlaying their GPS tracks and dive data, over a state-of-the-art ocean (POLCOMS) and acoustic (HARCAM) propagation model populated with real-time AIS shipping data in summer and winter. Our results show a clear influence of the seasonal thermocline (April-November) on shipping noise propagation. In summer the areas of high noise exposure were situated below the thermocline when the ship was located on the onshore side of oceanic fronts, and above the thermocline when the ship was on the offshore side of oceanic fronts. The difference in sound level between the top and bottom of the water column was as high as ~20dB. Shipping noise propagated much further (tens of kilometres) in winter than in summer. Furthermore, our study shows strong step changes of sound perceived by seals during their descent/ascent through water column. Since grey seals tend to be benthic foragers, the step-change in sound exposure may have negative impacts on their foraging behaviour. It is only through a more realistic understanding of exposure of animals to ship noise that we can set appropriate management and mitigation targets.
Transcript of Clare Embling 2015 Seals & Shipping Noise
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Chen F., Shapiro G., Bennett K.A., Ingram S.N., Thompson D., Vincent C., Russell D., Embling C.B.
@ClareEmbling @MarineVerts
Seals and shipping noise in a dynamic sea: seasonal changes in shipping noise exposure
experienced by diving seals
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Introduction
Shipping noise
Increasing continuously
A major contributor to ocean noise
Low frequency (10-1000Hz)
Detrimental effects on animals
Legislation of shipping noise
European Marine Strategy Framework Directive (MSFD)
International Marine Organisation (IMO)
International Whaling Commission (IWC)
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Aims and objectives
To examine how oceanic processes affect noise propagation
Summer and winter (stratified vs non-stratified)
Location of ship (onshore and offshore side of front)
To predict potential noise exposure by diving seals in 3D
Moving source (ship)
Moving receiver (seal)
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Modelling system
Ocean modelling: POLCOMS
Propagation modelling: HARCAM
Seal diving data
Real-time shipping AIS data
Temperature Salinity
Transmission loss (dB)
Sediments
Position, size and speed
Sound Exposure
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Courtesy of Bennett K.A.
Species
Grey Seal
~45% in UK
Able to hear noise
Benthic forager
Diving data
GPS tags
SW Wales
Sound frequency relationship between animal and ship
(B. Southall, NMFS/NOAA)
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Shipping density in UK
Map of shipping density around UK waters plotted by using ShipAIS(Shipping Automatic Identification System) data (BMT, 2013)
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Study area
The Celtic Sea
Shallow
Strong stratification
Temperature fronts
High shipping density
Ship track TransectLocations of the ship
A
B
Wales
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Temperature and Transmission Loss of transect A
Locations of the ship
Summer Winter
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Temperature and Transmission Loss of transect B
Locations of the ship
Summer Winter
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Cumulative Sound Exposure Level (SEL)
SEL at a water depth of 50mSummer Winter
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Diving profiles of a pup seal in 3D
2D view 3D view
ShipSeal
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Received level by a pup seal along diving path
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Received level by a pup seal along diving path
Bottom front
Bottom front
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Discussion and Conclusion
Oceanic processes (e.g. stratification and fronts) havestrong effects on noise propagation
High interactions with shipping noise
Benthic foragers
Able to travel large distance
Step changes in the sound level are frequent whileforaging, which may have negative effects on grey seals
How do grey seals respond to such step change of sound?
Path changes
Changes in diving
Relate changes to sound level
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Thank you for your attention !
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Pup
Adult
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Input TSWater column data: section 189
1. Observational data 2. Modelled data
Scanfish temperature data collected in the Celtic Sea in Aug 1998 (Brown et al., 2003)
Fully 3D predicted temperature data
Mean error: -0.17C RMSe: 0.83 Willmott skill (0 - 1): 0.97
Chen et al., 2013
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Input TSWater column data: section 202
1. Observational data 2. Modelled data
Scanfish temperature data collected in the Celtic Sea in Sep 1998 (Brown et al., 2003)
Fully 3D predicted temperature data
Mean error: -0.35C RMSe: 0.53 Willmott skill (0 - 1): 0.98
Chen et al., 2013
