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

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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. Akvaplan-niva AS, 9296 Tromsø 48 www.akvaplan.niva.no
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. Detailed site survey at PL531 Darwin Akvaplan-niva AS Rapport 6051 - 1 49
Page 1 and 2: Detailed visual seabed survey at dr
Page 3: Akvaplan -niva AS Rådgivning og fo
Page 6 and 7: List of figures and tables FIGURE1.
Page 8 and 9: Preface In August,2012,Akvaplan-niv
Page 10 and 11: Figure2. ROVtransectsandrecordsof s
Page 12 and 13: 2 Materials and methods 2.1 Vessel
Page 14 and 15: 2.3 Survey track and waypoints Thep
Page 16 and 17: Akvaplan-niva haspreviouslyworked w
Page 18 and 19: Figure7. Over4 tonnesof sponges(pre
Page 20 and 21: Figure10. BarentsSea.Spongebycatchi
Page 22 and 23: Somespongesform densereefs,and prov
Page 24 and 25: Figure14. Photosfrom Mercier(2012)s
Page 26 and 27: Figure16. Imagefrom Salina,2010,cla
Page 28 and 29: It is clear that Cochraneadopted a
Page 30 and 31: 5.2 Seafloor conditions 5.2.1 Sedim
Page 32 and 33: 5.3.2 Plots of sponge distribution
Page 34 and 35: Figure24. Locationof the 30 imagess
Page 36 and 37: Position16. 0-1 % coverage Position
Page 38 and 39: Position15. 1-5 % coverage.Geodiaan
Page 40 and 41: 5.3.3 Overall assessment of sponge
Page 42 and 43: 5.3.5 Dominant sponge species recor
Page 44 and 45: Hymedesmia Hymedesmia Polymastia Po
Page 46 and 47: Figure34. Observationsof the yellow
Page 48 and 49: Figure36. Observationsfor the blues
Page 50 and 51: Figure38. Upper:spottedwolffishrest
Page 54 and 55: Table 6. Summaryof environmentalcos
Page 56 and 57: 5.4.2.2 Deposition Case 2: to seafl
Page 58 and 59: 5.4.2.4 Deposition Case 7: Depositi
Page 60 and 61: 5.4.3 Comparative assessment Table7
Page 62 and 63: 6 References Auster, P.J. 2007. Lin
Page 64: Appendices Anelectronicsupplement(o

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

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