ThiscommunicationisacontributiontothePADDLEproject,whichhasreceivedfundingfromtheEuropeanUnion’sHorizon2020researchandinnovationprogrammeunderGrantagreementNo734271.

MSP’sspecialchallengesintropicalareasEcosystemdynamicspointofview:theactiveacousticsinputAnneLebourges-DhaussyIRD/UMRLEMAR

WhereistheacousticinputinMSP?

2

PADDLEProject(M.Bonnin)

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Advantagesu  Non-invasive and non-destructive

method u  Horizontally & vertically

continuous information (in opposite to stations) along large spatio-temporal scales

u  Allows deep observations (> 1000 m)

u  Provides a rather exhaustive view of the water column

Limitsu  Difficult specific identification of

organisms u  Only estimation of biomasses Trenkeletal.(2011)

Advantages&limitsofactiveacoustics

Acoustictoolsandtargets

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Benoit-Bird&Lawson,2015

Knowledgeavailablefromacoustics

  Fishstockassessment  Spatialdistributionofmarineorganisms  Time-seriesPredator/preysrelationships

  Distributions/environmentconditionsrelationships  HabitatsBehaviourstudies

Useful tool for ecosystemic approach Useful tool for monitoring changes impacts

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Knowledgeavailablefromacoustics

  Fishstockassessment  Spatialdistributionofmarineorganisms  Time-seriesPredator/preysrelationships

  Distributions/environmentconditionsrelationshipsBehaviourstudies

  Habitats

Useful tool for ecosystemic approach Useful tool for monitoring changes impacts

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Spatialdistributionandstockassessments

7

ExampleofsmallpelagicstockassessmentinPeru:here,resultsonanchovies

Acoustictransects

Samplingtrawls

CourtesyofM.Gutierrez

Onetransect

An acoustic transect: the formation of an Echogram (cf anim)

Surface

Bottom

Electricvoltagemeasuredateachtransmission

SaturedRed:transmittedsignal&bottomecho

Red:fishschools

Yellow,green,blue:youngfish,zooplankton,ofvarioussizesanddensities

20m

40m

Distancerun

Theechosounderprovides1transmission~eachsecond

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Howreachthemapsperspecies?

TheboatmovingTransmit/ Receive areas

Whatmaycauseanecho?

AnythingthatisanobstacletothepropagationAnobstacle=anyobjectwhichhasnotthesameacousticpropertiesthanthewater§ Density§ Wavepropagationcelerity

Air, gaz Bottom, rocks

Fish

Turbidity, zooplankton

Thehigherthecontrast,thehigherthereflectedpartofthewave

CourtesyofJ.Habasque

Atka mackerel

Eulachon

Capelin

Pacific herring

Walleye pollock

Mallotus villosus

Clupea pallasii

Theragra chalcogramma

Thaleichthys pacificus

Pleurogrammus monopterygius

Species Lateralview DorsalviewS.GauthierPers.Com.

Forthefish:Theswimbladder

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Echo-counting

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CourtesyofA.Bertrand

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Echogramwithdispersedfish

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Targetstrengthmeasurements=Fishechostrengthproportionaltoitslength

Echointegration

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CourtesyofA.Bertrand

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Echo-integration

ESDU

Forasetofpings,onanelementarysamplingdistanceunit andoveragivenwaterheight iscalculatedanintegrationoftheenergyreceived fromthereflectionofthewaveonthebiologicaltargets

Identificationofthedetections

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TypicalexamplesoffishschoolsdetectedintheBayofBiscay (N.Diner,Ifremer)

Trawlsamplings

AnchovyschoolsinPeru

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Characteristicsdependingontheplace

Biomassestimate

Allocationofafishassemblageorspeciesforeachsamplingdistanceunit

Acousticdensitymapsperspecies

Semi-empiricalmodelstorelateTargetStrength(TS)tolength(L):♦Clupéidés:TS=20logL-71.2dBèL=20cm,TS:-45.2dB♦Gadidés:TS=20logL-66dB èL=60cm,TS:-30.4dB♦Maquereau:TS=20logL-82dBèL=30cm,TS:-52.5dB(noswimbladder)

Conversionacousticdensity/fishweight

fromstandardequations

Closestrepresentative

trawl

Senegalexample:Twospeciesofsardinella

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PhDA.Sarré,2017RVItafDemeacousticsurveysof2005-2006-2007

NASC=acousticdensity

Lessonfromtimeseries

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Fish acous

tic densit

ies

Northern limit of

Sardinellas

detection from

fishing operation

s

Northern limit of vessel operations each year

Northwardtrendinthedistributionofsardinellafrom1995to2015 Fromacousticdensities,evolutionof

biomassesbarycenters

NorthwardtrendforS.aurita

PhDA.Sarré,2017

Contextofincreaseofseasurfacetemperatureoverthe

period

“Fisheries”threshold=-65dB“Ecosystemic”threshold=-90dBShip speed 0 m.s-1 de 0 a 5m.s-1

Peruvian echogram (M. Gutierrez, com. pers.)

Towardstheecosystemicacoustic,decreasingthethreshold…

38kHz 120kHz

70kHz 200kHz

…andincreasingthefrequencies

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Frequencysignaturesofmarineorganisms

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Benoit-Bird&Lawson,2015

Epipelagic layer

Ballón et al. (2011, PinO)

Exploitingfrequencypropertiesto discriminateorganisms

Gelatinous organisms?

1/Sv38+Sv120>threshold1? YES NO NO2/Sv38>Sv120?YESNO

3/Sv120>threshold2? YES NO

Epipelagic layer

Mappingthemacrozooplanktondistribution

Macrozooplankton,euphausiidsparticularly=anchoviespreys

(Bertrand et al., 2008, PinO)

Oxygèneisstructuringpelagicspecieshabitat(Bertrandetal.,2011PLoSONE)

Acousticsallowstheresolutiontothesubmesoscaleofthe

oxygenmeasurements=>potentialhabitatvolumeD

epth

(m)

OMZ

DO (mL/L)

Ballón et al. (2011, PinO)

Fishrelationshipswith:itspreys,itsenvironmentparameters

8018

6

781614

1210

872

7476

Latitude(ºS)

Longitu

de(ºW

)

0

150

100

50

Dep

th(m

)

Paita

PiscoCall

aoChimbot

e

Log(FishNAS

C+1)

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Bertrand et al. (2010, PLoS ONE)

Potentialanchovyhabitatvolume9187 km3

Crucero pelágico Feb. Abril 2005

Pelagichabitat

Benthichabitat

Soundersusedalsotocharacterizethebottomtypes

Lateral sonar, or multibeams, or vertical echosounders

Needs a training of the algorithms on known bottoms

28DAY NIGHT

Behaviourobservations:agregation/dispersion

Guillard&al.2004

Temperature

Impact on fishing

strategy

Amangroveapplicationofavertical echosounder

29Krumme&Hanning,2005

Floating device supporting the transducer

Study site in the center of the mangrove north of Bragança 24H time series of vertical distribution of fish tracks and current

speeds. UP: fish abundance versus depth cell versus time. LOWER: concurrent water level and and tidal current speed.

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FishinmangroveQuickturningfishobservedamidmangroveroots.

CourtesyofPeterJohnson,LGLNorthwestforSoundMetrics

Startofroots

Acousticcamerainamangrove: accesstonewareas

Monitoringmarineprotectedarea

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Example of the Coral Sea – New Caledonia, with a pluridisciplinary approach

Monitoringofamarineprotectedarea

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Example of the Coral Sea – New Caledonia

Acousticestimateoftunapreysdensity

Winter Summer

PhotoV.Allain,SPC

Trawledlayer

Micronektondiversitystudy

RVALISechosounderechogram

Tracking4tunasmigrations

DAY NIGHT

DAY

NIGHT

Micronektonmigrations

Monitoringsurroundingecosystemsaroundmarinerenewableenergydevices

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Anapproachthatitdevelopping:acousticequippedmooringsaroundMREdevicesExampleofWilliamson&al,2017work:Combinationofmultibeamandvertical

multifrequencyechosoundersaroundatidalturbinestructuretomonitormarinelifeandstudy:diveprofiles,depthpreferences,predator-preysinteractionsfishschoolingbehaviour

inconjunctionwiththehydrodynamicimpactofthedevice.

Multibeam principle (F. Gerlotto)

Challenge in the data processing due to high detections of bubbles.

Combined multibeam behaviour/multifrequency observations + vision (seabirds) to classify targets: no biological sampling.

Conclusion

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Thankyou!

A not invasive approach adapted for

- exhaustive description of the ecosystems - trophic relationships studies - highlight physical/biology interactions - evidence physical structures - monitor key areas

Training in ecosystem acoustic organised at UFPE-Récife in october 2017 october 2018