Detailed visual seabed survey at drilling site 7218/11-1

Detailed visual seabed survey at drilling 

site 7218/11-1, Darwin PL 531 in the 

Barents Sea 

- with special focus on sponge assemblages 

Akvaplan-niva AS Report: 6051 - 1

Cover picture: sponges at the sediment surface at Darwin, PL531, August, 2012. White: Geodia 

and yellow: Apl ysilla . Photo: Oceaneering AS/ Akvaplan -niva.

Akvaplan -niva AS 

Rådgivning og forskning innen miljø og akvakultur 

Org.nr: NO 937 375 158 MVA 

Framsenteret 

9296 Tromsø 

Tlf: 77 75 03 00, Fax: 77 75 03 01 

www.akvaplan.niva.no 

Report title 

Detailedvisualseabedsurveyat drilling site 7218/11-1, Darwin PL 531 in 

the BarentsSea- with specialfocuson spongeassemblages . 

Author(s) 

SabineCochrane 

RunePalerud 

JesperHansen 

AnnaHelenaFalk 

Client 

RepsolExplorationNorwayAS(RENAS) 

Akvaplan -niva report no. 

6051– 1 

Date 

25.09.2012 

No. of pages 

64 

Distribution 

Restricted 

Client’s reference 

SigurdHellem 

Summary 

On commissionto RENASNorway, Akvaplan-niva provided biological assistanceduring ROVsediment 

mappingaround the planneddrillingsite at the Darwinprospect(PL531)in the BarentsSea, August2012. 

ROVfilming along a transect length of approximately27 200 m was carried out, over approximately17 

hours.Thisreport documentsthe distributionanddensitiesof the spongepopulationsin the area,together 

with other biologicalandsedimentcharacteristics.In general,the seafloorcloseto the planneddrilling site 

at the Darwinprospectcanbe characterizedasmainlycomprisedof mud, with somescatteredstones. The 

area is visibly rich in bottom currents, and the visible sea-floor communitiesare dominated by sponges 

suchasGeodia,Aplysilla,Farreaoccaandassociatedorganismssuchassquatlobsters(Munida). 

Themain challengesfor spongeassessmentsare outlined, and the approachappliedduring the surveyis 

describedin detail. Further,a summaryof stateof knowledgeregardingspongesandmethodsof assessing 

spongeassemblagesisoutlined. 

Project manager Quality control ler 

SabineCochrane LarsHenrikLarsen 

© 2012 Akvaplan -niva AS. This report may only be copied as a whole. Copying of part of this 

report (sections of text, illustrations, tables, conclusions, etc.) and/or reproduction in other 

ways, is only permitted with written consent from Akvaplan -niva AS.

Table of Contents 

PREFACE ................................ ................................ ................................ ................................ ..........................4 

1 INTRODUCTION ................................ ................................ ................................ ................................ .............5 

1.1BACKGROUND................................ ................................ ................................ ................................ ...................5 

1.2SUMMARYOFPREVIOUSURVEYSATDARWIN................................ ................................ ................................ .........5 

1.2.1Baselinesurvey2011................................ ................................ ................................ ............................. 5 

1.2.2Additionalstudies2012................................ ................................ ................................ .........................6 

1.3AIMSANDCHALLENGES FORPRESENTSURVEY................................ ................................ ................................ ..........7 

2 MATERIALSANDMETHODS................................ ................................ ................................ ..........................8 

2.1VESSELANDNAVIGATION................................ ................................ ................................ ................................ .....8 

2.2ROV,VIDEOANDSTILLIMAGES................................ ................................ ................................ ............................. 8 

2.3SURVEYTRACKANDWAYPOINTS................................ ................................ ................................ ..........................10 

2.4OBSERVATIONLOGSANDEVENTLOGGING................................ ................................ ................................ .............11 

2.4.1Stepstakento addresschallenges................................ ................................ ................................ .......11 

2.4.2Eventlogging................................ ................................ ................................ ................................ .......12 

3 ABOUTSPONGESANDCHALLENGES FORASSESMENT................................ ................................ ...............13 

3.1OSPARHABITATCLASSIFICATI ONOFSPONGES ................................ ................................ ................................ .......13 

3.2SPONGESIN THESOUTH-WESTERNBARENTSEA................................ ................................ ................................ ....13 

3.3ABOUTSPONGES IN GENERAL................................ ................................ ................................ .............................. 16 

3.4RED-LISTEDSPONGES ................................ ................................ ................................ ................................ ........18 

3.5SPONGESASECOSYSTEMENGINEERS ................................ ................................ ................................ ....................19 

4 ABUNDANCEQUANTIFICATIONCHALLENGES - CASESTUDYSALINA,JUKSAANDDARWIN.........................21 

4.1GENERAL................................ ................................ ................................ ................................ ........................21 

4.2CURRENTAPPROACHES – ASSESSINGCOVERAGE ................................ ................................ ................................ .....22 

5 RESULTSANDDISCUSION................................ ................................ ................................ ...........................25 

5.1GENERALOBSERVATIONS ................................ ................................ ................................ ................................ ...25 

5.2SEAFLOORCONDITIONS................................ ................................ ................................ ................................ .....26 

5.2.1Sedimentcomposition................................ ................................ ................................ .........................26 

5.2.2Litter andotherhumanimpacts................................ ................................ ................................ ..........26 

5.2.3Seashorealgaeandfishfalls................................ ................................ ................................ ................27 

5.3DISTRIBUTIONMAPSANDSELECTED IMAGES................................ ................................ ................................ ..........27 

5.3.1Generaloverview................................ ................................ ................................ ................................ . 27 

5.3.2Plotsof spongedistributionanddensity................................ ................................ .............................. 28 

5.3.3Overallassessmentof spongedensitiesat the Darwinsite................................ ................................ . 36 

5.3.4Integratedassessment – baselinesurveyanddetailedsitesurvey................................ ......................37 

5.3.5Dominantspongespeciesrecordedin the currentsurvey................................ ................................ ...38 

5.3.6Trawltracks................................ ................................ ................................ ................................ .........44 

5.3.7Generalimpressions(images)................................ ................................ ................................ ..............45 

5.4ENVIRONMENTALCOSTSANDBENEFITSFORDISCHARGESCENARIOS ................................ ................................ ............48 

5.4.1Dischargescenarios................................ ................................ ................................ ............................. 48 

5.4.2Depositionscenariosrelatedto areaof impactto sponges................................ ................................ . 50 

5.4.3Comparativeassessment ................................ ................................ ................................ .....................56 

5.5ASSESSINGVULNERABILI TYOFSPONGEASSEMBL AGESTODRILLINGDISCHARGES ................................ ............................ 56 

5.5.1What do sensitivityandvulnerabilitymean?................................ ................................ .......................56 

5.5.2Ongoingandplannedexperimentalandin situ workon assessingsensitivityof spongesto drilling 

cuttings................................. ................................ ................................ ................................ ........................57 

6 REFERENCES ................................ ................................ ................................ ................................ .................58 

APPENDICES ................................ ................................ ................................ ................................ ....................60 

Detailed site survey at PL531 Darwin 

Akvaplan-niva AS Rapport 6051 - 1

List of figures and tables 

FIGURE1.EXPLORATIONWELL7218/11-1 (DARWIN) LOCATIONINTHEBARENTSEA(SOURCE 

: RENAS) ................................ ...5 

FIGURE2.ROVTRANSECTS ANDRECORDSOFSPONGESFOUNDATDARWINDURINGTHEBASELINESURVEYIN2011.THERELATIVE 

AMOUNTSOFTHEVARIOUSCATEGORIES OFSPONGEDENSITIESARESHOWNINTHEPIECHART. SEDIMENTSAMPLESWERETAKEN 

ATTHEREDDOTS(AXESCROSSES ).THESPUDLOCATIONISMARKEDWITHA BLUETRIANGLE(SEEARROW).FIGUREFROMDNV 

(2011)................................. ................................ ................................ ................................ ............................. 6 

FIGURE3.MSNJORDVIKING................................. ................................ ................................ ................................ ........8 

FIGURE4.MAGNUMROVSYSTEMUNDERDEPLOYMENTFROMNJORDVIKING. THEBLUECYLINDERATTHEBASEOFTHEROVISTHE 

HDSTILLCAMERA. PHOTOSABINECOCHRANE . ................................ ................................ ................................ .........9 

FIGURE5.INSTALLINGHDCAMERAONTHEMAGNUMROV.INCLUDEDTOGIVESCALETOTHEFIGUREABOVE. PHOTOSABINE 

COCHRANE . ................................ ................................ ................................ ................................ ........................9 

FIGURE6.PLANNEDSURVEYROUTEFORDETAILEDSITESURVEYATDARWIN, AUGUST2012................................. ....................11 

FIGURE7.OVER4 TONNESOFSPONGES(PRESUMABLY ACCIDENTA LLY) COLLECTED INA TRAWLDURINGA RESEARCH EXPEDITIONTO 

THETROMSØFLAKET , NORTHERNORWAYIN2007.IMAGE: NORWEGIANRESEARCHINSTITUTE 

(HTTP:// WWW.IMR.NO/ TOKT/ TOKTOMTALER/ OKOSYSTEMTOKTET /TOKTDAGBOK _2007/DEKKET_FULLT_AV_SVAMP/ NB-NO). 

................................ ................................ ................................ ................................ ................................ ......14 

FIGURE8.GEODIASPONGEASSEMBL AGEIN THENORTHWESTATLANTIC. IMAGE: NORTHWESTATLANTICFISHERIESORGANISATION ). 

................................ ................................ ................................ ................................ ................................ ......14 

FIGURE9.GENERALDISTRIBUTIONOFHABITAT-FORMINGSPONGES INTHENEATLANTICANDNORDICSEASASINDICATEDBYRECORDS 

IN THEOSPAR[…]DATABASE . CONCENTRATION OFSPONGESVARYCONSIDERABL YWITHINTHESEAREAS........................... 15 

FIGURE10.BARENTSEA. SPONGEBYCATCHIN RESEARCHBOTTOMTRAWLING1982-97SUPERIMPOSED ONFISHING..................16 

FIGURE11.GENERALSTRUCTURE OFA HYPOTHETICAL SPONGE. FIGUREFROMUNIVERSITYOFBERKELEY 

(HTTP:// WWW.UCMP.BERKELEY .EDU/ PORIFERA / PORIFERAMM .HTML)................................. ................................ ........17 

FIGURE12.SCANNINGELECTRONMICROSCOPE (SEM)IMAGEOFSPONGESPICULES. IMAGEFROM 

HTTP:// WWW.UCMP.BERKELEY .EDU/ PORIFERA / PORSKEL .HTML................................. ................................ .................17 

FIGURE13.LEFT: UNIDENTIFIEDSPONGEFROMTHEDEEP-WATERLICENSEBØNNA, HOMETOAPOPULATIONOFGAMMARID 

CRUSTACEANS ANDRIGHT: AGEODIACOLONY, OFFERINGSUBSTRATE ANDSHELTERFOROTHERORGANISMS . PHOTOLEFT: 

AKVAPLAN-NIVA/OCEANEERING /ENIRIGHT: ILLUSTRATION PHOTOGRA PH, UNKNOWNLOCATION................................. .....18 

FIGURE14.PHOTOSFROMMERCIER(2012)SHOWING(LEFT) A SEA-PENFIELDAND(RIGHT) DEVELOPINGLARVAEOFTHEREDFISH 

SEBASTESTUCKEDAMONGTHEPOLYPSOFTHESEAPENS . SIZEOFTHESEAPENS ISNOTGIVEN, BUTTHESCALEBARS ONTHERIGHT 

AREBOTH1 MM. ................................ ................................ ................................ ................................ ...............20 

FIGURE15.ABUNDANCESCALEDEFINEDBYDNV,2008.UPPERLEFTRARE, UPPE RIGHT, SCATTERED , LOWERLEFT, REGULARAND 

LOWERRIGHT, HIGHDENSITY ................................. ................................ ................................ ............................... 21 

FIGURE16.IMAGEFROMSALINA, 2010,CLASSIFIED ASHAVINGA HIGHDENSITYOFSPONGES . THEGENERALSEAFLOORPICTUREIS 

SIMILARALSOFORBOTHDARWINANDJUKSA. ................................ ................................ ................................ .........22 

FIGURE17.IMPROVISEDCONCEPTUAL VISUALISATIONOFSPONGECOVERAGE , USEDINJULY, 2012................................ ...........23 

FIGURE18.MATHEMATICALLY CALCULATED%COVERSCHEMEADOPTEDBYPALERUDANDHANSENDURINGTHEPRESENTVISUAL 

SURVEYATDARWIN, AUGUST, 2012................................. ................................ ................................ ....................24 

FIGURE19.VISUALREPRESENTATION OFDEPTHSRECORDEDDURINGTHESURVEY , BASEDONTHESURVEYLOG. THEPLANNE DRILLING 

LOCATIONATDARWINISSHOWNBYA YELLOWSTAR................................. ................................ ................................ 25 

FIGURE20.ILLUSTRATIVE IMAGE SHOWINGTYPICALSEDIMENTCONDITIONSATTHEDARWINFIELD, AUGUST, 2012.PHOTOS: 

OCEANEERINGAS................................ ................................ ................................ ................................ .............26 

FIGURE21.OBSERVATIONOFMARINELITTER. PIECEOFSHAPEDMETALOFUNKNOWNORIGIN................................. .................26 

FIGURE22.VISUALOBSERVATIONS OFESTIMATEDSPONGEDENSITIES , DARWIN, AUGUST2012................................ ...............28 

FIGURE23.MAPILLUSTRATING THEDENSITYESTIMATION(%COVERAGESPONGES ) ONTHESEDIMENTSURFACE. SEEMETHODS 

SECTIONFORQUANTIFI CATIONMETHOD. BLACKCROSSES INDICATEOBSERVATIONS ; DATAAREINTERPOLATE DBETWEENPOINTS 

BYTHEKRIGINGMETHODINSURFERPROGRAMME . ................................ ................................ ................................ 29 

FIGURE24.LOCATIONOFTHE30IMAGE SELECTED FORFURTHERANALYSIS ................................. ................................ .........30 

FIGURE25.PHOTOSFROMSELECTED POSITIONS , ILLUSTRATING THECATEGORY0-1 %COVERAGE . DARWINFIELD, AUGUST2012..31 

FIGURE26.PHOTOSFROMSELECTED POSITIONSWITH0-1 %COVERAGEOFSPONGESATDARWINAUGUST2012.THESEIMAGES 

TAKENEARLYMORNING, WHENFISHBECAMEABUNDANT................................. ................................ .......................... 32 

FIGURE27.PHOTOSFROMSELECTED POSITIONS(SEEMAPINFIGUREX) WITH1-5 %COVERAGEOFSPONGESATDARWINAUGUST 

2012................................. ................................ ................................ ................................ ............................. 33 

FIGURE28.PHOTOSFROMSELECTED POSITIONSWITH1-5 %COVERAGEOFSPONGESATDARWINAUGUST2012.......................34 

FIGURE29.PHOTOSFROMSELECTEDPOSITIONSWITH5-10%COVERAGEOFSPONGESATDARWINAUGUST2012.....................35 

FIGURE30.VISUALREPRESENTATION OFFREQUENCIES OFSPONGEABUNDANCECLASSESACROSSTHESTUDYAREA. UPPER: 

HISTOGRAMSHOWINGACTUALNUMBERSOFOBSERVATIONSANDLOWER: PIECHARTEXPRESSING RELATIVEFREQUENCIES AS 

Akvaplan-niva AS, 9296 Tromsø 

2 www.akvaplan.niva.no

PERCENTAGES . NOTETHAT0 %ABUNDANCE(NOTPRESENT ) SHOULDBECONSIDERED AS0-1 %.SEEIMAGESABOVE. THEREARE 

SELDOMNOSPONGESOVERMANYMETRESOFSEABED, THUS0 %ISA MATTEROFSCALEANDTIMING(TOTHEMILLISECOND ) OF 

WHENTHEOBSERVATIONWASMADE................................. ................................ ................................ ....................36 

FIGURE31.MAPOFOBSERVATIONS OFSPONGEDENSITIESCARRIEDOUTDURINGTHE2011BASELINESURVEYANDTHECURRENT 

2012DETAILEDVISUALSITESURVEY ................................. ................................ ................................ .....................37 

FIGURE32.IMAGESOFTHEMOSTDOMINANTSPONGESPECIES/ GROUPSOBSERVEDATTHEDARWINFIELD. ILLUSTRATION IMAGES 

FROMAKVAPLAN-NIVAARCHIVES ................................. ................................ ................................ .........................40 

FIGURE33.OBSERVATIONS OFTHEPOTATOSPONGEGEODIAATDARWIN, AUGUST, 2012................................. .....................41 

FIGURE34.OBSERVATIONS OFTHEYELLOWSPONGE , APLYSILLA , ATDARWIN, AUGUST2012................................. .................42 

FIGURE35.OBSERVATIONS OFTHEGLASS-SPONGEFARREAOCCAATDARWIN, AUGUST, 2012................................. ...............43 

FIGURE36.OBSERVATIONS FORTHEBLUESPONGEHYMEDESMA , DARWIN, AUGUST2012................................. ....................44 

FIGURE37.OBSERVATIONS OFTRAWLTRACKSATTHEDARWINFIELD, AUGUST, 2012................................ ........................... 45 

FIGURE38.UPPER: SPOTTEDWOLFISHRESTINGONTHESEDIMENT , AMONGTHEGLASS-SPONGEFARREAOCCA. LOWER:SAITHE, 

ATTRACTEDTOTHELIGHTSOFTHEROV................................ ................................ ................................ ...............46 

FIGURE39.UPPER: FISH(SAITHE) ANDPOSSIBLYA CORRODEDMETALFISHINGFLOATWITHSOMEBIOLOGICALGROWTHAND(LOWER) 

SPONGESONMUDDYSEDIMENT; GEODIAANDAPLYSILLA IN THEFOREGROUND , ANDFARREAOCCAFARTHERBACK(TOTHE 

RIGHT)................................. ................................ ................................ ................................ ............................ 47 

FIGURE40.LARGESTONEINFOREGROUND, WITHGROWTHOFWHATAPPEARSTOBEHYDROI DS. IN THEBACKGROUNDMUDDY 

SEDIMENTSANDERECTSPONGECOLONIES , FREQUENTED BYFISH................................. ................................ ................48 

FIGURE41.ILLUSTRATIONOFDEPOSITIONCASE1: DISCHARGE ATTHEORIGINALSPUDLOCATION. UPPER: OBSERVATIONS AND 

(LOWER) INTERPOLATED DISTRIBUTIONOFSPONGEABUNDANCES, WITHOVERLAYEDMODELEDSPATIALEXTENTOFDEPOSITED 

DRILLINGCUTTINGS(ASPROVIDEDBYSINTEF). ................................ ................................ ................................ .......51 

FIGURE42.ILLUSTRATIONOFDEPOSITIONCASE2: DISCHARGE FROMBOTHTHEORIGINALSPUDLOCATIONANDFROMRIG. UPPER: 

OBSERVA TIONSAND(LOWER) INTERPOLATED DISTRIBUTIONOFSPONGEABUNDANCES, WITHOVERLAYEDMODELEDSPATIAL 

EXTENTOFDEPOSITEDRILLINGMUD/ CUTTINGS(ASPROVIDEDBYSINTEF)................................ ................................ . 52 

FIGURE43.ILLUSTRATIONOFDEPOSITIONCASE6: DISCHARGE300M NORTHOFTHEORIGINALSPUDLOCATION. UPPER: 

OBSERVATIONS AND(LOWER) ESTIMATIONSOFSPONGEABUNDANCES , WITHOVERLAYEDMODELEDSPATIALEXTENTOF 

DEPOSITEDRILLINGMUD/ CUTTINGS(ASPROVIDEDBYSINTEF)................................ ................................ ...............53 

FIGURE44.ILLUSTRATIONOFDEPOSITIONCASE7: DISCHARGE ATTHENEWSPUDLOCATION(UPDATE21.09.2012).UPPER: 

OBSERVATIONS AND(LOWER). INTERPOLATED ESTIMATI ONSOFSPONGEABUNDANCES, WITHOVERLAYEDMODELEDSPATIAL 

EXTENTOFDEPOSITEDRILLINGMUD/ CUTTINGS(ASPROVIDEDBYSINTEF)................................ ................................ 54 

FIGURE45.ILLUSTRATIONOFDEPOSITIONCASE6A: DISCHARGENORTH-EASTOFTHESPUDLOCATION. UPPER: OBSERVATIONS AND 

(LOWER) INTERPOLATED ESTIMATIONSOFSPONGEABUNDANCES, WITHOVERLAYEDMODELEDSPATIALEXTENTOFDEPOSITED 

DRILLINGMUD/ CUTTINGS(ASPROVIDEDBYSINTEF). ................................ ................................ ............................... 55 

TABLE1.DESIGNATEDWAYPOINTSFORTHEPRESENTSURVEY. POSITIONSFROMRENAS................................ ........................10 

TABLE2.EXTRACTFROMTABLE8 INKÅLÅSETAL., 2010.COUNTYDISTRIBUTIONOFTHENUMBEROFTHREATENEDANDNEAR 

THREATENED SPECIESBASEDONDATAFROMTHERØDLISTEDATABASE , ANDCONCERNSKNOWNCURRENTOCCURRENCES OR 

ASSUMEDCURRENTOCCURRENCESBASEDONEARLIEROBSERVATIONS ................................. ................................ .........18 

TABLE3.EXTRACTFROMEUROPEANSTANDARDCEN/TC230/WG2/TG7"WATERQUALITY—VISUALSEABEDSURVEYSUSING 

REMOTELYOPERATEDANDTOWEDOBSERVATIONGEARFORCOLLECTIONOFENVIRONMENTAL DATA". ............................... 23 

TABLE4.LISTOFTHEMOSTFREQUENTLYRECORDEDSPONGESPECIES / GROUPSATTHEDARWINFIELD, AUGUST, 2012.SIMPLIFIED 

IDENTIFICATION CHARACTERISTICS AREPROVIDEDTOASSISTNON-SPECIALISTS ................................. ............................... 38 

TABLE5.EXTRACTFROMOSPAR2010,LISTINGTHEMAINPRESSURESWHICHMAYAFFECTSPONGEPOPULATIONS......................49 

TABLE6.SUMMARYOFENVIRONMENTALCOSTSANDBENEFI TSASSOCIATEDWITHTHETHREEMAINTYPESOFDISCHARGESCENARI OS. 

................................ ................................ ................................ ................................ ................................ ......50 

TABLE7.COMPARISONOFTHEEXTENTOFIMPACTSTOTHESEAFLOORANDSPONGEASSEMBLAGES , UNDER5 DIFFERENTDISCHARGE 

SCENARIOS . NOTECASE7 ISCALCULATED FORTHENEWSPUDLOCATION(UPDATED21.09.2012)WHEREASTHEOTHER 

SCENARIOS AREBASEDONTHEORIGINALSPUDLOCATION. ................................ ................................ .......................56 


Akvaplan-niva AS Rapport 6051 - 3

Preface 

In August,2012,Akvaplan-niva wascontractedby RepsolExplorationNorwayAS(RENAS) to conduct 

a detailedvisualseafloorsurveyat the Darwinprospectin the south-westernBarentsSea(PL531). 

The backgroundfor the survey is the presenceof deep-sea spongeassemblages(a habitat type 

definedassensitiveby OSPAR) . A detailedmappingis requiredin order for both the industryandthe 

regulatory authorities to plan the most appropriate strategy for handlingof drill cuttings in areas 

with sponges. The main aim of the surveytherefore was to map the distribution and densitiesof 

spongeassemblages,andgeneralseafloorconditionsin the vicinityof the planneddrilling site. 

We thank the master, Paul Aasen,and crew of MS Njord Viking for excelent cooperation. ROV 

supervisorsand pilots from OceaneeringASare gratefully acknowledgedfor their skill and cheerful 

attitude to unfamiliartasksregardingbiologicalsurveying.We thank the surveyorsfrom iSURVEYAS, 

for enablinggeo-referencedbiologicalrecordings.Finally,specialthanksto SigurdHellem,RENAS, for 

surveyplanningand necessarydiscussions.Other RENASand Proactimastaff alsoare acknowledged 

for their contributions. 

Surveyparticipantswere: 

Akvaplan-niva (biologicalservices) OceaneeringAS(ROVservices) 

SabineCochrane(landcontact,reporting) RuneAustvoll(supervisor) 

JesperHansen(fieldwork) HansM. Dahle 

RunePalerud(fieldwork,maps,analyses) StianJacobsen 

HelenaFalk(imagecompilation) EmmaSletten 

KjetilRisnes 

iSURVEYAS(surveyors) HåvardFredheim 

BjørnEdvardsen, senioroffshoresurveyor 

DagAtle Skår, offshoresurveyor 



1 Introduction 

1.1 Background 

RepsolExplorationNorway AS(RENAS)is planningthe Darwin exploration well, 7218/11-1, (ED50 

UTM34N 8.001.215,E411.870)in PL531.Thewell is locatedapproximately133nauticalmiles(246 

km) North Westof Hammerfestand177nauticalmiles(327km)North Westof Banakairport. 

Drillingat the well is plannedto be carriedout in in December2012.Duringthe planning, a needfor 

a detailed baselinesurvey to map spongedensitiesin the vicinity of the well location has been 

identified. Thepurposeof the Surveywasto identify potentialareasnearthe drillinglocationsuitable 

for depositingdrill cuttings.. 

Figure1.ExplorationWell7218/11-1 (Darwin) locationin the BarentsSea(source:RENAS) 

Thewater depth at the location is approximately320 metres., and the water movementalongthe 

seabedduring the previous survey periods and assessmentscarried out in 2011 and 2012 (DNV 

2011a; 2011b,2012) indicateda strongnorth-eastwarddirection. 

1.2 Summary of previous survey s at Darwin 

1.2.1 Baseline survey 2011 

Duringthe baselinesurveyat Darwin in 2011(DNV2011)areaswith high density areasof sponges 

wereidentified(text insertedfrom DNV2011a/b): 

“Darwin is regardedas a speciesrich habitat with 49 taxa of benthic mega fauna recorded. The 

seabedat Darwinhadhighdensitiesof soft bottom sponges.Spongecoverin category“high density” 

constituted11.8%of the benthichabitat. ThismakesDarwinthe most spongerich field in the 2011 

survey.Figure2 (note: Figure5-14 in original report) showsthe distribution of spongesat Darwin. 

Therewere no recordingsof coralsor red-listed speciesduringthe visualmonitoring.Squatlobsters 

were the most abundantmobile macro fauna and occurredin high numbersbetween spongesand 

pebbles.Relativelyfew echinodermspecieswereobservedcomparedto other fields." 


Akvaplan-niva AS Rapport 6051 - 1 5

Figure2. ROVtransectsandrecordsof spongesfoundat Darwinduringthe baselinesurveyin 2011. Therelative 

amountsof the variouscategoriesof spongedensitiesare shownin the pie chart.Sedimentsamplesweretaken 

at the red dots (axescrosses).TheSPUDlocation is markedwith a blue triangle (seearrow). Figurefrom DNV 

(2011). 

The baseline survey did not reveal the presenceof soft or hard corals at the Darwin field. 

Furthermore,no red-list specieswere identified. The specieswith the highestregistereddensities 

were the squat lobster Munida spp. as well as spongespeciessuch as Geodia. Relatively high 

densitiesof soft bottom spongespecieswererecordedin the area, with 85.2%of the benthichabitat 

containing "scattered" to "high densities"of sponges.Darwinhad the highestrecordingsof sponge 

densities,relativeto other nearbyfieldssurveyedin 2011. (text modifiedfrom DNV2011). 

Qualitativeabundanceclassesappliedby DNVare: 1. Singlespecimen/rare, 2. Scattered,3. Common 

and4. Highdensity.Illustrationsof thesedensityclassificationsare givenin Section2, Materialsand 

methods. 

1.2.2 Additional studies 2012 

Basedon the resultsfrom the BaselineSurvey,duringthe planningof the well RENASaskedDNVto 

go deeperinto the data and try to identify areaswith low densityof spongeswere a CTSsolution 

could be deployedfor cuttingsdeposition.In addition SINTEFwas askedto model the spreadingof 

cuttingsby different cuttingshandlingsolutions. 

DNV(2012) summarizetheir findings:"Thescopeof work wasto assessthe distribution of deepsea 

spongesat Darwinby data interpolations.Byusingspongedensitydata from the BarentsSeavisual 

survey2011, interpolated maps were made, showingcalculatedvaluesof spongedensitiesin the 

drilling area.Backgrounddata like spongedensitiesfrom other fields and sedimentsamplingdata 

was included in the evaluation of the sponge situation at the Darwin field". DNV have made 

recommendationsfor locationsfor drill cutting depositionthat were estimatedto havethe lowest 

impacton the spongeassemblages . 



1.3 Aims and challenges for present survey 

RENAScommissioneda new and more detailed visual sea bed surveyin the vicinity of the SPUD 

location (ED50UTM34N 8.001.215,E 411.870)for the well at Darwin (PL531). The survey was 

performed with parallel ROVlines 25 m apart, coveringa square of 800 times 800m within the 

coordinates(ED50UTM34)E 411.600to E 412.400,and N8.000.800 to N 8.001.600,around the 

plannedDarwin explorationwell, 7218/11-1. The estimatedtotal surveydistancefor the proposed 

programis28 km (15nm). 

Theprimaryaimsof the environmentalsurvey,asgivenby RENASare: 

Map the presenceof spongesand other vulnerable specieson the sea bed around the 

planned spud location with a higher resolution than during the 2011 visual survey (DNV 

2011).If possible,the extentof areaswith sponge aggregationsis to be defined; 

Distinguishbetweensoft benthosandhardbenthosspeciesandcommunities; 

Identify asmuchaspossibleof the observedfaunato specieslevel; 

Givea descriptionof the generalvulnerabilityof the area. 

Secondaryaims: 

Map areaaccordingto coverage,accordingto table in NS9435:2009,and identify speciesor 

subgroupsin the area; 

Adviseand report on suitable cuttings deposition sites for a CTSsolution basedon fauna 

observations(spongedensities). 

RENASfurther specified:"The mappingshall have the highest spatial resolution closeto the well 

locations(combinationof 2011and2012survey).Themappingshallfollow the proposedpath, but it 

shall also take actual observationsinto accountduring ROVsurveying.The onboard biologistsare 

responsiblefor the path optimization. 

Thesurvey will be conductedwith an ROVthat asa minimum havea video camerawith sufficient 

lights and subseapositioningsystem.It is preferableto haveHDstill picture camerawith flashlight, 

HD video camera and laser for distance measurements(two laser beams with a set distance 

between). HD still and camerashould be connected. The surveylog shall provide geo-referenced 

biologicalregistrations.". 

Note:in practiceit is not alwayspossibleto provideall thesespecificationsunderthe time restrictions 

whichapply, but theseshallbethe aim. 



2 Materials and methods 

2.1 Vessel and navigation 

Fieldworkwascarriedout usingthe Danish-registered85m vesselMS Njord Viking(Figure3). Total 

expedition period was from 17.08.2012 - 19.08.2012. Mobilisation and demobilisation was at 

HammerfestPolarbase. 

Figure3. MSNjordViking. 

Vesselpositioningwascarriedout in cooperationbetweenthe ship'scaptainandthe surveyorsfrom 

iSURVEYAS. 

2.2 ROV, video and still images 

A MAGNUM ® ROV(Remotely Operated Vehicle) system was used, which is a side entry cage 

deployed,dual manipulator 170hp heavy work classROV(Figure4 and Figure5). The systemis 

deliveredand operatedby OceaneeringAS.Thecageor TetherManagementSystem(TMS)supplies 

an additional85hp,is capableof poweringskidsandalsohasthruster control andauto heading.The 

wincheswere equippedwith a heavecompensationdevice. 

The videosystempre-installedon the MagnumROVwasused,andan additionalHighDefinition(HD) 

still camera (Imenco Tiger Shark)was installed. Two flashes were installed, but the angle was 

potentially not optimal becauseof the physicallimitations of the ROV-frame. A twin pair of Imenco 

line laserswereinstalledadjustedto 10 cmbetweenlines. 



Figure4. MagnumROVsystemunderdeploymentfrom NjordViking. Thebluecylinderat the baseof the ROVis 

the HDstill camera.PhotoSabineCochrane. 

Figure5. InstallingHDcameraon the Magnum ROV.Includedto give scaleto the figure above.PhotoSabine 

Cochrane. 



2.3 Survey track and waypoints 

Theplannedwaypointswere providedby RENASandare givenin Table1. 

Table1. Designatedwaypointsfor the presentsurvey.Positionsfrom RENAS. 

Easting Northing Easting Northing 

WP001 412400 8000800 WP034 412000 8001600 

WP002 412400 8001600 WP035 411975 8001600 









WP011 412275 8001600 WP044 411875 8000800 























Theplannedsurveytrackisshownin Figure6. 



Figure6. Plannedsurveyroutefor detailedsite surveyat Darwin,August2012. 

Thesurveygrid comprised33 lines,eachof which is 800m in length.Thedistancebetweenthe lines 

is 25 m. The total length of the survey route (using a hypothetical straight line between the 

waypointsand includingthe transit between lines) was approximately 27 200 m (26 400 m if only 

linesare included). All the abovewaypointswere used,althoughthe actualROVtrack variedslightly 

accordingto currentsand objects of biologicalinterest. Because currentswere reported to havea 

strongeasterlydirection,the directionof the maintracklineswasrotated 90 degrees. 

The ROVwas launchedon 18.08.2012at 13:53 local time (-2h for UTC),starting from the first 

waypoint at 14:41. The survey was completed on 19:08.2012 at 06:24 and ROVrecovery was 

completed at 06:47. Total video time was 17h 05m 06s, and total ROVdeploymenttime was the 

same(videopermanentlyon). 

2.4 Observation logs and event logging 

2.4.1 Steps taken to address challenges 

Oneof the challengesof conducting biologicalanalysesfrom non-geo-referencedvideo and/or still 

photographsis the time-consumingwork of matching imagesor recorded 'events' to geographic 

positions.TheROVdive log recordsthe time of eachnote, or event taken,but the positionsneedto 

be matchedwith the surveyorlog.Thesurveyorlog continuouslyrecordsthe ROVtrack,but doesnot 

containthe biologicalobservations. 


Akvaplan-niva AS Rapport 6051 - 1 11

Akvaplan-niva haspreviouslyworked with iSURVEYto developa systemwhich allowsthe biological 

events (i.e. observations)to be taken without havingto stop the surveyorlogging.Usually,event 

recordingrequiresa 'fix' procedure,whichtakesapproximately3 minutesto complete.Thiswould be 

too time-consumingfor all our biologicalobservations,and would have forced us to restrict the 

number of geo-referencedobservationsmade. The surveyorson-board from iSURVEYproduceda 

customised recording system, which allowed biologists to click on a number of pre-defined 

categories,asbiologicalrecordingsweremade. 

2.4.2 Event logging 

In the ROVcontrol room, the biologistsweregivena PClinkedto the surveylog,andcouldmakegeoreferencedobservationsas 

event logs. A number of pre-defined categorieswere made, allowing 

rapidrecording.Additionalnotescouldbemadefor eachof these. 

o Sediment(absenceof recordingmeansonly mud andsmallerstoneswereobserved): 

Stone 

Stonewith growth 

Boulder 

Boulderwith growth 

o Fauna(alphabeticalorder,latin namefirst, colloquialdescriptivecharacteristicgiven) 

Sponges 

Aplysilla (yellow) 

Candelabrum(string) 

Axinella(funnel) 

Farreaocca(bumpy) 

Geodia(potato) 

Hymedesmia(blue) 

Polymastia(dog'sball; with spikes) 

Stylochordyla(stalked) 

Otherfauna 

Ascidiacea(seasquirts) 

Annelida(worms) 

Anthozoa(seaanemonesandseapens) 

Bryozoa 

Crustacea 

o Decapoda(Crabs) 

o Decapoda(Hermitcrabs) 

o Gammaridae(smallshrimps) 

o Isopoda 

o Munida(Squatlobster) 

o Pandalus(the commercialshrimp) 

Echinodermata 

o Asteroidae(starfish) 

o Holothuroidae(seacucumbers) 

o Ophiuroidae(brittle-stars) 

o (pillow-stars) 

Fish 

Mollusca(shells) 

o Otherobservations 

Litter (objectsspecified) 

Macroalgae(recordedto showconnectionsbetweenthe shoreandthe offshore 

shelf) 



3 About sponges and challenges for assessment 

3.1 OSPAR habitat classification of sponges 

Offshore sponges in the south-western Barents Sea are classified under the OSPAR habitat 

descriptionas"DeepSeaspongeaggregations". Thefollowingtext is modifiedfrom OSPAR(2005): 

Deepseaspongeaggregationsare principallycomposedof spongesfrom two classes:Hexactinellida 

andDemospongia.Glasssponges(Hexactinellidae)tend to be the dominantgroupof spongesin the 

deep sea although demospongidssuch as Cladorhizaand Asbestoplumaare also present. The 

massivespongesthat dominate some areas include Geodia barretti, G. macandrewi,and Isops 

phlegraei.Theycan occurat very high densities,particularlyon the slopein areaswhere substrate 

and hydrographicconditionsare favourable.Surveymaterial from a spongefield in the northern 

North Seaand other locationshad a comparablediversityanddensityof spongeswith tropical reefs 

(Konnecker,2002). The spongesalso influence the density and occurrenceof other speciesby 

providingshelterto smallepifauna,within the osculaand canalsystem,and an elevated perch,e.g. 

for brittlestars(Konnecker,2002).Deep-seaspongeshavesimilarhabitat preferencesto cold-water 

corals,and henceare often found at the samelocation.Researchhasshownthat the densemats of 

spiculespresent around spongefields may inhibit colonisationby infaunal animals,resulting in a 

dominanceof epifaunalelements(Gubbay,2002).Information indicatesthat dominant speciesare 

slow growingtaking severaldecadesto reachlargesize(Klitgaard& Tendal,2001).Thehabitat and 

the rich diverse associatedfauna is therefore likely to take many years to recover if adversely 

affected(Konnecker,2002). 

Theyoccurbetweenwater depthsof 250-1300m(Bett & Rice,1992),where the water temperature 

rangesfrom 4-10°Candthere is moderate currentvelocity(0.5knots).Deep-seaspongeaggregations 

may be found on soft substrataor hard substrata,suchas bouldersand cobbleswhich may lie on 

sediment.Icebergplough-mark zonesprovidean ideal habitat for spongesbecausestableboulders 

and cobbles,exposedon the seabed,providenumerousattachment/settlementpoints(B.Bett, pers 

comm.). However,with 3.5kg of pure siliceousspiculematerial per m 2 reported from some sites 

(Gubbay,2002),the occurrenceof spongefields canalter the characteristicsof surroundingmuddy 

sediments.Densitiesof occurrenceare hardto quantify,but spongesin the classHexactinellidahave 

been reported at densitiesof 4-5 per m², whilst ‘massive’growth forms of spongesfrom class 

Demospongiahavebeenreported at densitiesof 0.5-1 per m 2 (B.Bett,pers. comm.). 

3.2 Sponges in the south -western Barents Sea 

Spongesare found in most sea-floor (benthic)faunalassemblages,both on hard andsoft substrates. 

In the south-westernpart of the BarentsSea(precisearea not specifiedhere),spongescompriseup 

to 57 % of the benthic biomass(Ereskovsky,1995).Slightlyfarther east,along the Murman coast, 

almost80%of the recordedbiomasswasdue to sponges(Propp,1971).Extremelyhigh densitiesof 

spongesalso have been recorded in the Tromsøflaketarea west of the Troms/Finnmarkarea in 

northern Norway(Figure7). 



Figure7. Over4 tonnesof sponges(presumablyaccidentally)collectedin a trawl duringa researchexpeditionto 

the Tromsøflaket, northern Norway in 2007. Image: Norwegian Research Institute 

(http://www.imr.no/tokt/toktomtaler/ okosystemtoktet/toktdagbok_2007/dekket_fullt_av_svamp/nb -no). 

TheNorwegianseafloorand habitat mappingprogrammeMAREANOhascharacterizedspongebeds 

asa habitat on the Tromsøflaket(seewww.mareano.no– at time of writing, spongemap facility out 

of order on website).Densespongeaggregationsare knownglobally.Geodiaspongebedshavebeen 

well documentedalsoin the north-westernAtlantic(Canada;Figure8). 

Figure 8. Geodia sponge assemblagein the Northwest Atlantic. Image: Northwest Atlantic Fisheries 

Organisation). 

In European waters, attention has been raised by OSPARto dense, habitat-forming sponge 

associations(Figure9). 



Figure9. Generaldistribution of habitat-forming spongesin the NEAtlantic and NordicSeasas indicatedby 

recordsin the OSPAR[…]database.Concentrationof spongesvaryconsiderablywithin theseareas. 

In the BarentsSea,spongecatchesin trawls(fisheriesandresearch)havebeennoted (Figure10). The 

following is an extract from OSPAR(2010). "The western Barents Sea is well known for mass 

occurrencesof spongesfrom numerousscientificand fishermen sources(reviewedby Klitgaard& 

Tendal2004).Between150and 350m depth,spongesof up to 1 m diameterandcontributingup to 

95-98 %of the localtotal biomasssamplesand up to 5-6 kg*m-2 were found to occuron sandyand 

sandy-silty bottom with good water movement. The speciescomposition correspondsto the 

“Atlantic“ band group as describedby Klitgaardand Tendal(2004,seeabove)and includesGeodia 

barretti, G.macandrewi,Geodia(former Isops)phlegraei,I. pyriformes, andother species." 



Figure10. BarentsSea.Spongebycatchin researchbottom trawling 1982-97 superimposedon fishing 

effort 2004(asdensityof VMSdata points,NorwayMin. Env.2005-2006).Redstar indicatesthe approximate 

positionof Salina, JuksaandDarwin. 

3.3 About sponges in general 

Spongesare filter-feeders,and therefore act asa direct link betweenthe water columnand benthic 

fauna. Most feed on matter dissolvedor suspendedin the water column, suchas diverseorganic 

material, algae and bacteria. Their anatomy varies from small, simple forms to large complex 

structures,but essentiallythe bodyhasone or severalchambersthroughwhichwater is pumped. 

Becausespongesare sessile,and they dependon water flow, they are reputed to be sensitiveto 

sedimentation.However,data basedon experimentalstudiesare spares,and as a result, ongoing 

studies in Norway (Akvaplan-niva, IRIS,Institute of Marine Research)and internationally, are 

addressingsensitivity of spongesto various discharges. This note will not addressthe issue of 

sensitivity,but will focuson distribution recordsandchallengesrelatingto assessingdensity. 



Figure 11. General structure of a hypothetical sponge. Figure from University of Berkeley 

(http://www.ucmp.berkeley.edu/porifera/poriferamm.html ). 

Insidethe spongeis a densematrix of spicules,whichform a skeletonto allow the animalto retain its 

shape (Figure 12). Thesespiculesare of siliceousand/or calcareousmaterial, dependingon the 

group. 

Figure 12. Scanning electron microscope (SEM) image of sponge spicules. Image from 

http://www.ucmp.berkeley.edu/porifera/porskel.html. 

Sponges,like many large sessile (non-moving) organisms,act as habitat for other organisms. 

Individualspongescan give shelter to for examplesmallcrustaceansand bristleworms(Figure13). 



Somespongesform densereefs,and providehabitat for a wide rangeof organisms,in a similarway 

to coralreefs(seeBuhl-Mortensenet al.2010). 

Figure13. Left: unidentifiedspongefrom the deep-water licenseBønna,home to a population of gammarid 

crustaceansand Right: a Geodia colony, offering substrate and shelter for other organisms.Photo left: 

Akvaplan-niva/Oceaneering/Eni right: Illustrationphotograph,unknownlocation. 

All spongesgive habitat to other organisms,but the ecosystemimplicationsvary with scale.Small, 

individualspongecoloniesare hometo mainlysmallinvertebratesand bacteria,whereaslargereefformingspongescanoffer 

protection alsoto largerinvertebratesandfish. 

3.4 Red-listed sponges 

The Norwegianred-list for species(Artsdatabanken,2010) lists one sponge,Geodiasimplicissima 

undercategoryDD(datadeficient).Listedin termsof countiesin Norway,there are no spongeslisted 

asbeingthreatenedor in declinein northern Norway(Table2). 

Table2. Extractfrom Table8 in Kålåset al., 2010.Countydistribution of the numberof threatenedand near 

threatened speciesbased on data from the Rødlistedatabase,and concernsknown current occurrencesor 

assumedcurrentoccurrencesbasedon earlierobservations. 



Geodia belongs within the Demospongiae, and is an extremely species-rich genus (see 

http://www.marinespecies.org/aphia.php?p= taxdetails&id=132005). Differences between species 

generallylie in the finer detailsof the skeleton,or spicules,and therefore these usuallycannot be 

identified with certainty from pictures or videos.Geodiasimplicissimais regardedas a speciesof 

uncertain status. The following is an extract from the International Marine SpeciesIdentification 

Portalhttp://species-identification.org/species.php?species_group=s ponges&id=234) 

SpeciesOverview 

GeodiasimplicissmaBurton (1931)is known only from a few fragmentsfrom Northern Norway.The 

differencewith the more commonG.barretti and G.cydoniumis microscopical:it hasan ectosomal 

palisadeof smalloxeaslyingperipheralto the crustof sterrasters. 

TaxonomicDescription 

Colour: Unknown. 

Shape,size,surfaceand consistency: Knownonly from a few fragments,so no detailsof the habit 

areknown. 

Spicules: Megascleres: Huge oxeas:2200 x 32 µm; "microxeas"(= cortical oxeas):250 x 4 µm; 

orthotriaenes:shaft1700x 48 µm, cladi320µm; a singleanatriaenewith cladiof 150µm wasfound. 

Microscleres: Sterrasters,spherical:70 µm; pycnasters:4 µm. 

Skeleton: (Geodiasimplicissimaskel) Ectosomal: a palisadeof microxeasis erectedon the sterraster 

layer, which in its turn is carriedby the cladi of the orthotriaenes.Choanosomal : radial bundlesof 

oxeasandorthotriaenes. 

Ecology: In fjords,10-75 m. 

Distribution: NorthernNorway. 

Etymology: The name presumably refers to the relatively simple spicule complement. 

Typespecimeninformation: Thetype is in the NaturalHistoryMuseum,London:BMNH1913.6.1.36. 

Remarks 

Thedescriptionis unsatisfactoryandthe specificdistinctnessisdoubtful. 

3.5 Sponges as ecosystem engineers 

Sponges,corals and also sea-pens have long been acknowledgedfor their role as autogenic 

(individual-based) ecosystemengineers (Miller et al., 2012 and numerous references therein). 

Ecosystem engineersprovide living spacefor other organisms(Figure14), or they may alter the 

physicalpropertiesof the immediatehabitat (in the caseof sponges,they filter large quantities of 

water daily, and provide small-scale shelter from bottom currents). Thus they can alter the 

biodiversityin areaswhichthey occupy,andhavea role in influencingsea-floor ecosystemfunction. 

ThelargeGeodiasponges,andalsoother unidentifiedbranchingforms,in the south-westernBarents 

Seaevidentlyprovidehabitat for organismssuchassquat lobsters.Thesecanbe seenin burrowsat 

the baseof the sponge,with clawsextended.Alsoother invertebratesareexpectedto takeshelterin 

this way. During filming, fish were frequently seen to feed from the bases of the sponges 

(presumablypreying on the resident invertebrates),but they seldom did damageto the actual 

sponges.However,occasionally,fish were seento "accidentally"bite off a chunkof a sponge,and 

then later ejectit from their mouths.Personalobservations,S.Cochrane. 



Figure14. Photosfrom Mercier(2012)showing(left) a sea-penfield and (right) developinglarvaeof the redfish 

Sebastestuckedamong the polypsof the seapens.Sizeof the seapensis not given,but the scalebarson the 

right are both 1 mm. 

The ecologicalrole of sponges,and their responsesto environmentalconditionsare to someextent 

documentedfor shallow-waters (seefor exampleBell & Smith,2004),we have few studieswhich 

clarify the role of coralsand spongesas autogenic engineersin deeperwater (Miller et al., 2012). 

Thoseauthors further state"[…]nevertheless,many fishes and macroinvertebratesinhabit deepwater 

coral (Rogers,1999, Husebøoet al., 2002, Mortensen & Buhl Mortensen, 2005 and Stone, 

2006) and sponge(Beulieu,2001, Marliave et al., 2009) habitats. Unlike shallow-water systems, 

where the processesconnectinghabitat with populationsand communitiesof dependantorganisms 

are relatively well understood,the role of habitat structure, includingthat of autogenicecosystem 

engineers,in deep-water communitiesis still uncleardue to lack of small-scaleobservationaland 

experimentalstudies(Auster,2007). 

Obviously,the role of spongesas ecosystemengineersis a question of scale.At a small scale,an 

individual spongeprovides a habitat for a range of other organisms,but to be significantat an 

ecosystemscalerequiresthat large areasand/or large amountsof spongesare involved. Thisbegs 

the question to which we have no clear answer – how many sponges, or how large an area 

constitutes a resource of ecosystemsignificance?Further, how can we then assessissuesof 

vulnerabilityto humanactivities,or conservationstatus. 

The UK Biodiversity Action plan (http://jncc.defra.gov.uk/pdf/UKBAP_BAPHabitats -12- 

DeepSeaSpongeComms.pdf ) contains some interesting remarks, about sponge abundances, 

extractedfrom OSPAR(2008). "Densitiesof occurrenceare hard to quantify,but spongesin the class 

Hexactinellidahave been reported at densities of 4-5 per m², whilst ‘massive’growth forms of 

spongesfrom classDemospongiahave been reported at densitiesof 0.5-1 per m 2 (B. Bett, pers. 

comm.)." In this context,we canassumethat "massivegrowth forms" meanslargeindividuals,such 

asthe Geodiaspecimensin the BarentsSea, whichcanmeasure30-40 cm andmorein diameter. 



4 Abundance quantification challenges - case study 

Salina, Juksa and Darwin 

4.1 General 

Not only are spongesdifficult to identify, but they alsoare difficult to quantify from the type of data 

usuallycarriedout in connectionwith pre-drilling surveys.TheCENstandard(CENprEN16260)for 

visualassessmentsgivesguidanceon an abundancescale,but this requires knowledgeof numbersof 

spongesper unit area.Duringvisualsurveys,it is not alwayspossibleto uselaserbeamsduringall of 

the filming,andalsothe flight heightoften dependson individualconditions.Becausespongesin the 

south-westernpart of the BarentsSeaoften are verypatchilydistributed,estimatinga standardarea 

(m2)from a smaller(or larger)areausuallyisnot representativeof the realsituation. 

Duringvisualassessmentscarriedout during 2008,a 4-level abundancescalewas devisedby DNV, 

basedon minimum to maximumspongedensitiesrepresentativefor the RegionIX area. Thisscale 

alsowasusedat Salinain 2010(Akvaplan-niva)andJuksaandDarwinin 2011(DNV). 

Figure15. Abundancescaledefinedby DNV,2008.Upperleft rare,upperright, scattered,lowerleft, regularand 

lowerright, highdensity. 

At Salina,six of the imagesselectedfor detailed faunal analyseswere classifiedas havinga high 

densityof sponges,accordingto the abovescheme(Figure16). 



Figure16. Imagefrom Salina,2010,classifiedashavinga high densityof sponges.Thegeneralseafloorpicture 

issimilaralsofor both DarwinandJuksa. 

When comparingimages,it is clear that scaleplaysa very large part in how relative abundanceis 

perceived(comparelower two imagesin Figure15 with Figure16). Subjectively,the round Geodia 

(?barretti) spongesare estimated to have a maximum diameter of around 10 cm, but without 

consistentlaserscale,we cannotsayfor certain.If the imageabovehadbeentakenat a lower zoom 

(or higher flight distance),it might havebeen difficult to distinguishbetween "regular abundance" 

and"high abundance". 

Anothersourceof biasis that there hasbeenno attempt to comparedensitiesreportedby trawl (see 

Figure7) with imagesfrom the south-westernpart of the BarentsSea. Intuitively, the phrase'high 

density' conjuresimagesof tonnes of sponges(capturedalong an entire trawl route), whereasthe 

reality in termsof individualcoloniesper m 2 (or km 2 ) is quite different. 

The baselinesurveyscarried out at the three fields were not intended to provide a quantitative 

assessmentof sponges,andthereforethe abundancescalesare only of useto comparebetweenthe 

five planned drilling sites documented. Subjectiveabundancescalesalso are notoriously userspecific,and 

so it also is not guaranteedthat another user would have classedthese imagesin 

exactlythe sameway(seealsoour methodologicalexperiencesoutlinedin Section4.2). 

4.2 Current approach es – assessing coverage 

DuringJuly,2012,CochraneandGeraudiefrom Akvaplan-niva conductedsimilarsite assessmentsat 

the nearbyfields Salina(PL533) and Juksa(PL490). Theneed for thesemissionsaroseat very short 

notice,andwe attempted to devisea methodologybasedon practicalpossibility,but asobjective as 

possible, and with reference to the international Europeanstandard for visual assessmentsof 

biodiversity(CENFprEN16260). Coverageof organismsis recommendedto be recordedin terms of 

numbersof individuals/coloniesper m 2 , or %coverfor encrustingorganisms(Table3). 



Table3. Extractfrom EuropeanstandardCEN/TC230/WG2/TG7"Water quality— Visualseabedsurveysusing 

remotelyoperatedandtowedobservationgearfor collectionof environmental data". 

The ideal would be to record numbersof spongesper unit area of seabed,but this is simply not 

possiblewhile the ROVis in motion. Further,unlessthe ROVis set at an altimeter andwith standard 

pitch androll, suchquantificationsare difficult. Thereasonwe chosenot to use'fixed' navigationfor 

the ROVis the survey programmerequestedthat objectsof biologicalinterest are filmed, and this 

requireszoomingin or out asappropriate. 

Giventhe short mobilisationtime, we constructeda makeshiftsystemto visualiseour recordingsin 

termsof %coverof sponges(i.e.how muchof the unit of seafloorobservediscoveredby sponges).If 

the actualvaluesturned out to be "wrong", we reasonedthat we couldadjust them later; the main 

point wasobjectivityandconsistencybetweenthe different observers.Ourfirst improvisedsystemis 

shownin Figure17. 

Figure17. Improvisedconceptualvisualisationof spongecoverage,usedin July,2012 



It is clear that Cochraneadopted a "biologicallyintuitive" approach,the reasoningbeing that since 

spongesare round or irregularlyshaped,evenat maximalcoverage,there still will be someareasof 

sedimentvisible.Duringmobilisationfor the current surveyat Darwin,to two different Akvaplan-niva 

observers,Palerudand Hansenconductedthe survey. In the interveningtime betweensurveys,we 

were ableto givethe matter considerablygreaterattention. Duringefforts to standardiserecording 

strategies, they adopted a more precise "mathematical" approach. A guidance scheme was 

developed,andthe precise%coverof spongerelativeto sedimentwasrecordedandprinted out asa 

template. It is clear that the schemeabovegivesfar higher % cover figures than the mathematical 

approach. 

Figure18. Mathematicallycalculated%coverschemeadoptedby Palerudand Hansenduringthe presentvisual 

surveyat Darwin,August,2012. 

Bell& Smith(2004)adopteda mathematicalcoveragesystemto quantify spongesfrom still images 

of sponges. Theyprojectedthe photographsonto a grid of 400dots,andcountedthe numberof dots 

which landed on a sponge,and from this calculateda % cover figure. Thisis compatiblewith the 

current approach, but in-situ visual surveyspresent the challengethat the operators must make 

continual, qualitative decisionson estimated % cover. There is a clear potential optical illusion – 

actual23%coverasshownaboveintuitively seemsdenser.Trainingis required to ensureconsistent 

recordings. 

Whateverthe classificationmethod used,it alsois veryclearthat we facean urgentchallenge– how 

to classifyspongedensitieswith correctmeaning?Thephrase5 %covertendsto provokereactions 

of – "that's not much", whereasat the samedensity,a trawl might pick up more than one tonne of 

spongesin a singlehaul. If another observeris more 'intuitively' biased,that samedensitymight be 

reportedat higherclassifications. 

We recommenda standardisationof approachesbetweenoperatorsat leastin Norway,to makesure 

we observeandreport in a similarmanner.Fromthis starting-point, we needfurther studyto be able 

to translate%coverinto vulnerabilityandprotectionstatusat an ecosystemscale. 

Forthe currentassessment,we placeemphasison the following: 

Visualimagesof spongeassemblages, to illustratethe variousabundancecategories; 

Holistic and integrated assessmentof the impacts of drilling mud/cuttings on the 

environment 

o on the sea floor, but also other impacts of the related pressuressuch as energy 

consumption(emissionsto air); 

o interpretation of environmentalcostsandbenefitsof variousdischargescenarios. 

Assessmentof overallvulnerabilityandsensitivity– canwe answerthe necessary questions? 



5 Results and discussion 

5.1 General observations 

A total of 1950observationswere made,and recordedasevent fixeson the surveylog. Thesewere 

distributedwithin categoriesasgivenin Section2.4.2. 

RecordedROVdepths variedfrom approximately310 – 335 m (Figure19). Someminor troughsand 

depressionsare evident in the central to upper part of the surveyarea, notably also closeto the 

SPUDlocation. We estimatethe ROVflying height to be between 1-2 m abovethe seafloor, such 

that the actual water depths should be adjustedaccordingly.Despitethis, the chart givesa good 

representationof the relativevariationin bottom topographyacrossthe studyarea. 

Figure19. Visualrepresentationof depthsrecordedduring the survey,basedon the surveylog. Theplanned 

drillinglocationat Darwinisshownby a yellowstar. 



5.2 Seafloor conditions 

5.2.1 Sediment composition 

Thesedimentat Darwingenerallycomprisedmud, with occasionalscatteredstonesand smallrocks 

on the surface(Figure20). 

Figure20. Illustrative imagesshowingtypical sedimentconditionsat the Darwin field, August,2012.Photos: 

OceaneeringAS. 

5.2.2 Litter and other human impacts 

Twoobservationsof litter were made(Figure21 andpossiblyalsoFigure39). 

Figure21. Observationof marinelitter. Pieceof shapedmetalof unknownorigin. 



5.2.3 Seashore algae and fishfalls 

Theoffshoreenvironmentoften is perceivedto be a barrenenvironment,remotefrom the processes 

which occur alongthe coast.However,often we find relatively fresh piecesof seaweedoriginating 

from the shore, andthis indicatesa dynamictransport pathwayfrom the coastto the offshorestudy 

areas. 

Onlyoneobservationof macroalgaewasmade(position411675.2/ 8000871; not photographed). 

5.3 Distribution maps and selected images 

5.3.1 General overview 

During the ROVsurvey1366 pictures were taken of the sea bottom. The bottom generallyhad a 

smooth surfaceand the depth varied from appr. 310 – 335 m. Thedepth variationswere affecting 

the angleof the ROVusingduringthe survey,resultingin a variationof angledpictures.Asa result,it 

is difficult to make accuratecalculationsof the area of sediment present in each picture. A laser 

beam is showinga distanceof 10 cm between the lines, but also the length of the beam varies 

accordingto the angleof the ROV. 

Further, during periods where fish shoalsare abundantnear the seafloor (from around 4 am and 

towardsafternoon),the lights on the ROVattracted largeamountsof curiousfish duringthe survey, 

mainly coalfish (Pollachiusvirens). Thesemadefilming of spongesdifficult becausethey stir up the 

sedimentsurface. 



5.3.2 Plots of sponge distribution and density 

We haveadopted two methods for presentingobservationsof spongedensities.First, a 'dot-map' 

showingthe actualobservationsmadealongthe ROVtrack (Figure22). Becausethis canbe visually 

difficult to interpret, we alsopresentdistribution maps,where the distribution of spongedensities 

areinterpolatedin-betweenthe actualobservationpoints,usingthe SURFERprogramme(Figure23). 

Estimatedspongedensities(%of sedimentsurfaceoccupiedby sponge)rangedfrom 0 %to 15-25 %, 

andgenerallyweredistributedall overthe surveyarea. 

Figure22. Visualobservationsof estimatedspongedensities,Darwin,August2012 



Figure23. Map illustrating the densityestimation(%coveragesponges)on the sedimentsurface.Seemethods 

sectionfor quantificationmethod.Blackcrossesindicateobservations;data are interpolatedbetweenpointsby 

the krigingmethodin SURFERprogramme. 

Basedon Figure23, a total of 30 positionswere selectedfor a more detailed analysisof biological 

conditions (Figure 24). Thesewere placed in areasrepresentativeof the various spongedensity 

assessments,andserveto 'ground-truth' the visualassessmentsmadeduringthe field mission. 



Figure24. Locationof the 30 imagesselected for further analysis. 

Theselectedimagesareshownin Figure25 to Figure29. 



Position2. 0-1 % coverage Position3. 0-1 % coverage.Geodia Position4. 0-1 % coverage 

Position5. 0-1 % coverage Position8. 0-1 % coverage.GeodiaandAplysilla Position10.0-1 % coverage.Geodia 

Figure25. Photosfrom selectedpositions,illustratingthe category0-1 %coverage.Darwinfield,August2012. 



Position16. 0-1 % coverage Position 18. 0-1 % coverage Position 20. 0-1 % coverage 

Position25. 0-1 % coverage Position 27. 0-1 % coverage.GeodiaandAplysilla Position 9. 0-1 % coverage.GeodiaandAplysilla 

Figure26. Photosfrom selectedpositionswith 0-1 %coverageof spongesat Darwinaugust2012.Theseimagestakenearlymorning,whenfishbecameabundant. 



Position1. 1-5 % coverage.GeodiaandAplysilla Position 6. 1-5 % coverage.GeodiaandAplysilla Position 7. 1-5 % coverage.GeodiaandAplysilla 

Position 11. 1-5 % coverage. Aplysilla, Farrea, Geodia, Position 12. 1-5 % coverage.GeodiaandAplysilla Position 14. 1-5 % coverage.Geodia,Aplysilla andFarrea 

HymedesmiandPolymastia 

Figure27. Photosfrom selectedpositions(seemapin figurex) with 1-5 %coverageof spongesat Darwinaugust2012. 



Position15. 1-5 % coverage.GeodiaandAplysilla Position 19. 1-5 % coverage.GeodiaandAplysilla Position 24. 1-5 % coverage.GeodiaandAplysilla 

Position26. 1-5 % coverage.Geodiaand?Mycale. Position29. 1-5 % coverage.Geodia,Aplysilla andFarrea Position13. 1-5 % coverage.GeodiaandAplysilla 

Figure28. Photosfrom selectedpositionswith 1-5 %coverageof spongesat DarwinAugust2012. 



Position 17. 5-10 % coverage.Geodia, Aplysilla and 

Farrea 

Position 22. 5-10 % coverage.Geodia, Aplysilla and 

Farrea 

Position 30. 5-10 % coverage.Aplysilla, Farrea, Geodia, Position 21. 5-10 % coverage.Geodia, Aplysilla and 

Hymedesmi andPolymastia 

Farrea 

Figure29. Photosfrom selected positions with 5-10 %coverageof spongesat Darwinaugust2012. 


Akvaplan-niva AS Rapport 6051 - 1 35 

Position 23. 5-10 % coverage.Geodia, Aplysilla, Mycale 

Position 28. 5-10 % coverage.Farrea

5.3.3 Overall assessment of sponge densities at the Darwin site 

Figure30 showsthe proportion of the variousspongedensitiesencounteredacrossthe surveyarea. 

Most of the areawasclassedashaving1-5 %coverof sponges,with similarproportionsof areaswith 

practically0 %sponges(seefiguretext) and5-10 %coverage. 

Figure30. Visual representationof frequenciesof spongeabundanceclassesacrossthe study area. Upper: 

histogram showingactual numbersof observationsand lower: pie chart expressingrelative frequenciesas 

percentages.Note that 0 %abundance(not present)shouldbe consideredas 0-1 %.Seeimagesabove.There 

are seldom no spongesover many metres of seabed,thus 0 % is a matter of scale and timing (to the 

millisecond)of whenthe observationwasmade. 



5.3.4 Integrated assessment – baseline survey and detailed site survey 

Figure31showsthe combinedobservationsof spongedensitiesmadeduring the baselinesurveyin 

2011(DNV)andthe currentsurvey. 

Initially, we aimed to integrate the abundancecategoriesto provide a combinedassessment,but 

without re-analysing the original images,we could not integrate these efficiently. A decisionwas 

taken to simply use the current recordings,but to work together with DNV in the future, to 

standardiserecordingapproaches. 

Figure31. Map of observationsof spongedensitiescarriedout duringthe 2011baselinesurveyand the current 

2012detailedvisualsitesurvey. 



5.3.5 Dominant sponge species recorded in the current survey 

Table4 liststhe mostcommonspongesrecordedat the Darwinfield. 

Table4. Listof the mostfrequentlyrecordedspongespecies/groupsat the Darwinfield,August,2012. Simplified 

identificationcharacteristicsareprovidedto assistnon-specialists. 

Sponges Simplified identi fication characteristics 

Aplysilla sp. Yellow lumps 

Axinella sp. White funnel 

Candelabrum phrygium Pink string 

Farrea occa White and bumpy 

Geodia sp. White potato 

Hymedesmia sp. Flat and blue 

Polymastia sp. Dog's rubber ball (white) 

Stylochordyla borealis Stalked tulip (white) 

Imagesof eachof these species/groupsare shown in Figure32. Note, figure extendsover several 

pages. 

Aplysilla Aplysilla 

Axinella Axinella 



Candelabrum phrygium Candelabrum phrygium 

Farreaocca Farreaocca 

Geodia Geodia 



Hymedesmia Hymedesmia 

Polymastia Polymastia 

Stylochordyla borealis Stylochordyla borealis 

Figure32. Imagesof the mostdominantspongespecies/groupsobserved at the Darwinfield. Illustrationimages 

from Akvaplan-nivaarchives. 



Theapproximatedistributionof the potato spongeGeodiais shownin Figure33. 

Figure33. Observationsof the potato spongeGeodiaat Darwin,August,2012. 

This obviously is a common species, and occurs acrossalmost all of the survey area. We can 

thereforeconsiderit asa keyspeciesfor the area,but it is by no meansrare. 

Figure34 showsthe observeddistribution of the yellow spongeAplysilla. It appearsto be somewhat 

more patchily distributed than Geodia, but still can be considereda common and typical sponge 

speciesfor the area. 



Figure34. Observationsof the yellowsponge,Aplysilla,at Darwin,August2012. 

Figure35 and Figure36 showthe distributionsof the glassspongeFarreaoccaand the blue sponge 

Hymedesma. Boththesespongesare rather morepatchilydistributed than Geodia, but still shouldbe 

consideredasdominantspecies/groupswhicharetypicalfor the area. 



Figure35. Observationsof the glass-spongeFarreaoccaat Darwin,August,2012. 



Figure36. Observationsfor the bluespongeHymedesma, Darwin,August2012. 

5.3.6 Trawl tracks 

Figure 37 shows the distribution of trawl tracks at the Darwin field, August,2012. Evidenceof 

trawling existsthroughout the area.Trawltrackswere observedat almosthalf of all the ROVsurvey 

lines. A total of 19 observationsof trawl tracksweremade. 



Figure37. Observationsof trawl tracksat the Darwinfield,August,2012. 

5.3.7 General impressions (images) 

During the course of the survey, it becameclear that the Darwin area supports a healthy fish 

population (Figure38). Fishspeciesobservedwere saithe (Pollachiusvirens), Atlantic cod (Gadus 

morhua), spottedwolfish (Anarhichasminor), redfish(Sebastes) anda variety of others.Fishtend to 

become numerous at the sea floor, and attracted to the ROVlights from early in the morning, 

approximately4am (pers. com. Knut Bergen,OceaneeringROVsupervisor),and this also was the 

casein the presentsurvey. 



Figure38. Upper:spottedwolffishrestingon the sediment,amongthe glass-spongeFarreaocca.Lower:saithe, 

attractedto the lightsof the ROV. 



Figure39. Upper:fish (saithe) and possibly a corrodedmetal fishing float with somebiologicalgrowth and 

(lower)spongeson muddysediment;Geodiaand Aplysillain the foreground,and Farreaoccafarther back(to 

the right). 

Figure40 showsa typicalexampleof a largestonewith growth. 



Figure40. Largestonein foreground,with growth of what appearsto be hydroids.In the backgroundmuddy 

sedimentsanderectspongecolonies,frequentedby fish. 

5.4 Environmental costs and benefits for disch arge scenarios 

5.4.1 Discharge scenarios 

Managementof human pressuresto the environment can be consideredwithin an ecosystem 

perspective,whereimpactsandremedialactionsoperateat a rangeof time-scales(short,middleand 

long-term). Environmentalbenefits of remedialaction to one ecosystemcomponentmay result in 

negative impacts on another, and these need to be evaluatedwithin an integrated assessment 

strategy. 



Table5. Extractfrom OSPAR2010,listingthe mainpressureswhichmayaffect spongepopulations. 

Fisheriesand CO2 emissionsare listed as posing large-scale,very high threats. Fisheriesare not 

consideredfurther here. However,CO2 emissionsare consideredto be one of the main causesof 

oceanacidification,and this inhibits the calcificationprocesses,which certainly coralsand at least 

somegroupsof spongesrely upon.Therefore,emissionsto air duringoperationalactivitiesshouldbe 

seen in the ecosystemcontext of managementof spongeand/or coral habitats in the vicinity of 

petroleum operations.Oceanacidificationis listed asa pressurerequiringmonitoring within the EU 

Marine StrategyFrameworkDirective(MSFD;Directive2008),and also featuresin the Norwegian 

IntegratedManagementPlanfor the Barents Sea(availableon www. regjeringen.no). 

ThepressuresMineralsexploitationandDumpingof solidwastecanbe seenwithin the MSFDimpact 

categoriesof habitat loss and habitat damage,in this case having local impacts (OSPAR,2010). 

Obviously, if local impacts become very numerous, there arises an increased risk of habitat 

fragmentation,but in the BarentsSeaat this time, this appearsto be of minor concern. 

Thetime-scaleof impactsshouldalsobe givenattention. If spongesrecolonizelocallyaffected areas 

during the averagelifecycleof a successfulpetroleum project (perhaps30+ years),these might be 

consideredashavinghighimpacts(spongemortality) at a localgeographicscaleandshort-term time 

scale, but negligible in the long term. Such impacts are consideredwithin the MSFDas being 

'reversible'.Of major concernis permanentlossor irreversiblenegativeimpacts.Oceanacidification 

posessuchanirreversiblethreat. 

Theenvironmentalcostsandbenefitsof the three maindischargescenariosare givenin Table6. 



Table 6. Summaryof environmentalcosts and benefits associatedwith the three main types of discharge 

scenarios. 

Scenario Cost Benefit 

Dischargeon sea floor 

directlyat SPUDsite 

Dischargeat seafloor to 

another location with 

lower spongedensity. 

5.4.2 Deposition scenarios related to area of impact to sponges 

SINTEFhave previously modelled likely spatial extent of depositions of drilling muds/cuttings, 

specified in terms of depositionthicknesses. We havethen compiledthe biologicalobservationsof 

spongeabundanceswithin eachof the modelled areasof deposition.On this basis,we present an 

estimate of area of affected seafloor containing the various categoriesof sponge abundances 

(Section5.4.3, Table7). TheRENASapplicationfor permit to operatepresentsdifferent alternatives 

for handlingof cuttingsreferred to asCase1 – 7. Thedischargescenariospresentedbelow refer to 

thesecases. 

Note: the dischargescenarioswere workedout usingthe originalSPUDlocation;but on 21.09.2012, 

Case7 wasupdatedto a new location.Thepositionsareasfollows(both usingED50Zone34N): 

Longitude Latitude 

ExplorationWell -original 411870 8001215 

ExplorationWell - new 411923 8001225 

1 CO2 emissionsare seenin the context of beinga major contributor to oceanacidificationthrough uptaketo 

the seafrom air. 

Short- to middle-term local mortality to 

spongeswithin anareaof between20 – 70 km 2 

(dependingon mortality to different particle 

sizefractions) 

Additional energy consumption (CO 2 

emissions 1 ) from vesselsin operation using 

dynamicpositioning(DP). Averageof 30 m 3 fuel 

consumption per day per vessel is not 

unrealistic (pers. comm. Captain of Njord 

Viking). 

Physical damage to sea floor/sponges by 

pipeline. 

Localimpactsto another areahinderingfuture 

(short-to-middle-term) sponge recruitment at 

this location 

Dischargefrom rig Additionalenergycosts(seeabove) 

Sedimentationpotentially spreadover a wider 

area. 

Without data on lethal limits for 

exposure to sedimentation, no 

guaranteedischargesare abovelethal 

limits. 

If not, riskof moreextensiveimpacts. 

Impact strictly localised. 

Minimalhabitat fragmentation 

Long-term local recolonisation 

is likely (e.g. within the lifetime 

of the project– 30years+) 

Spongesdirectly at the SPUD 

siteminimallyimpacted. 

Lower intensity of impacts 

immediately around the SPUD 

location. 



5.4.2.1 Deposition Case 1: to seafloor at original SPUD location 

Figure41 showsobserved and estimated spongeabundancesin relation to a dischargescenario 

wheredrillingcuttingsaredepositedat the originalSPUDlocation. 

Figure41. Illustration of depositionCase1: dischargeat the original SPUDlocation. Upper:observationsand 

(lower) interpolated distribution of spongeabundances,with overlayedmodelledspatial extent of deposited 

drilling cuttings(asprovidedby SINTEF). 



5.4.2.2 Deposition Case 2: to seafloor (CTS) and from rig 

Figure42 shows observedand estimated spongeabundancesin relation to a dischargescenario 

where the drilling cuttings from the top section are deposited 200m in a north-north-westerly 

directionfrom the originalSPUDlocation, andthe remainingcuttingsaredischargedfrom the rig. 

Figure42. Illustrationof depositionCase2: dischargefrom both the originalSPUDlocationand from rig. Upper: 

observationsand (lower) interpolated distribution of spongeabundances, with overlayedmodelled spatial 

extentof depositeddrilling mud/cuttings(asprovidedby SINTEF) 



5.4.2.3 Deposition Case 6: to seafloor 300 m north of original SPUD 

Figure42 shows observedand estimated spongeabundancesin relation to a dischargescenario 

wheredrillingmudsaredeposited300m north of the originalSPUDlocation. 

Figure 43. Illustration of depositionCase6: discharge300 m north of the original SPUDlocation. Upper: 

observationsand (lower) estimations of sponge abundances,with overlayed modelled spatial extent of 

depositeddrilling mud/cuttings(asprovidedbySINTEF). 



5.4.2.4 Deposition Case 7: Deposition at new, relocated SPUD location 

Figure44 showsobservedand estimatedspongeabundancesin a dischargescenariowhere drilling 

mudsaredepositedat the new SPUDlocation(X:411923mE;Y8001225mN(ED50Zone34N). 

Figure44. Illustration of depositionCase7: discharge at the new SPUDlocation (update21.09.2012) 

. Upper: 

observationsand (lower). Interpolated estimationsof spongeabundances,with overlayedmodelledspatial 

extentof depositeddrilling mud/cuttings(asprovidedbySINTEF). 



5.4.2.5 Deposition Case 6a: depositio n north -east of original SPUD 

Figure45 showsobservedand estimated spongeabundancesin relation to a dischargescenario 

where drilling muds are depositedat the seafloor, slightly to the north-east of the original SPUD 

location. 

Figure45. Illustrationof depositionCase6a: dischargenorth-eastof the SPUDlocation.Upper:observationsand 

(lower) interpolated estimationsof spongeabundances,with overlayedmodelledspatial extent of deposited 

drilling mud/cuttings(asprovidedbySINTEF). 



5.4.3 Comparative assessment 

Table7 showsvariousexpressionsof extent of impactsunderthe variousdischargescenarios.Case7 

usesthe new SPUDlocationandis shownin bold. 

Table 7. Comparisonof the extent of impacts to the seafloor and spongeassemblages,under 5 different 

dischargescenarios.Note Case7 is calculatedfor the new SPUDlocation (updated21.09.2012)whereasthe 

otherscenariosarebasedon the originalSPUDlocation. 

Case1 Case2 Case6 Case7 Case6a 

Spatialextent of impacts 

Affectedarea1-3 mm (m2) 71426 113031 71928 25341 71928 

Affectedarea3-10mm (m2) 44913 57388 45916 12249 45916 

Affectedarea10-30 mm (m2) 19767 18289 23587 7289 23587 

Numberof observationsin affectedareas 

No.Observations1-3mm0-1 %cover 27 42 19 16 57 

No.Observations1-3mm1-5 %cover 272 397 233 112 330 



No.Observations1-3mm>15%cover 0 0 0 0 0 

Proportionsof observationsin affectedareas 

%areaaffected1-3mm0-1%cover 8 % 9 % 7 % 11 % 14 % 

%areaaffected1-3mm1-5 %cover 81 % 82 % 83 % 78 % 81 % 



%areaaffected1-3mm>15%cover 0 % 0 % 0 % 0 % 0 % 

Case7 hasthe lowest spatialextent of impacts.Note that areasaffected by higher sedimentation 

than 30 mm thicknessarenot distinguishedin this exercise. 

5.5 Assessing vulnerability of sponge assemblages to drilling 

discharges 

5.5.1 What do sensitivity and vulnerability mean? 

We candefine sensitivityin terms of how muchreactionis causedby specificactions.In the caseof 

sponges,we canidentify what environmentalfactorshavea positiveandnegativeeffect on sponges. 

Generally,sponges,likeother benthicorganisms,areaffectedby: 

Foodsupplyfrom the upperwater layers 

Propertiesof the bottom water masses 

Sedimentationof particles 

o Forspongesexcessivesedimentationis assumedto causesmothering 

Exposureto chemicalsandphysicaldamage 

o May alter the ability to perform basic body functions (respiration, feeding and 

disposalof wasteproducts) 

Organismsare vulnerableif any of the abovefactorsare likely to be altered in the areain question, 

usuallyby ongoingclimaticchangesor humanactivities. 



For example,spongesare sensitiveto physicaldamage(suchas trawling or anchor handling)and 

smothering(suchasfrom passingtrawls or depositionof drilling muds),but they are only vulnerable 

in areaswheretheseactivitiesactuallyoccur. 

Assessingsensitivity to drilling cuttings requires further research on sponge metabolism and 

responsesto various disturbances(see below). Sensitivity and vulnerability can therefore be 

measuredat an individual scale,but for environmentalmanagementand conservationissues,an 

ecosystemperspectiveusuallyis adopted. 

Arisingquestionsaretherefore: 

Howmuchimpactswill be causedby plannedactivities 

Amountof spongeseradicatedor reducedin function; 

Howlongwill the effectsremainvisibleon the sea-floor 

Arethe impactsshort,middleor long-term? 

Will remedialactionshaveother undesirableenvironmentalside-effects 

Disposalin marinehabitatsversustransportto coastalor terrestrialzone 

Disposalof solidwasteversusemissionsto air 

To date, we do not havereal answersto these questionsin relation to spongeassemblagesin the 

Barents Sea.In responseto emerging needs, a number of researchinitiatives are taking place 

(Akvaplan-niva,Institute for MarineResearchandIRIS;seealsobelow). 

5.5.2 Ongoing and planned experimental and in situ work on assessing 

sensitivit y of sponges to drilling cuttings. 

Recently(05.09.2012),Akvaplan-niva submitted a researchproposal to the NorwegianResearch 

CouncilPROOFNYprogramme,on the impacts of drilling cuttings on spongeassemblagesin the 

south-westernBarentsSea.RENAS, together with EniNorgeand Lundin,hasgivenan expressionof 

interest to function as an end-user to this research. In addition, these companieswill guide the 

selectionof experimentalexposureparameters,and, where possibleor practical,offer assistancein 

collection/ in-situ studyof sponges,shouldan opportunity ariseduringanyfuture visualsurveillance 

or stand-by missionswhereROVservicescanbe usedto mutual benefit. 

Thisreal link betweenexperimentalresearchand industrialneedsis a major stepforwards,towards 

answeringsomeof the urgentquestionsraisedduringthis, andrelateddetailedsite surveys. 

Howmuchsedimentationislethal to sponges? 

o Andwhichsedimentfractioncausesmost stressto sponges? 

How do spongesreact to exposureof someof the substancesusedduring operations(e.g. 

BariteandBentonite)? 

How is the metabolism/respiration/ generalperformanceof spongesaffectedby sub-lethal 

exposureto drillingdischarges? 

How fast do spongesgrow, and therefore what is the expected recovery period after 

depositionof drillingmud/cuttings? 

o note – another question arises- do spongesreadily recolonize,despitechangesin 

the grainsizecompositionat the sedimentsurface? 



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Appendices 

Anelectronicsupplement(on externalharddisk)isgivento RENAS, includingall dataandthis report.

Detailed visual seabed survey at drilling site 7218/11-1

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