Designation:E2122−02(Reapproved2013)StandardGuideforConductingIn-situFieldBioassaysWithCagedBivalves1ThisstandardisissuedunderthefixeddesignationE2122;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguidedescribesproceduresforconductingcon-trolledexperimentswithcagedbivalvesunderfieldconditions.Thepurposeofthisapproachistofacilitatethesimultaneouscollectionoffielddatatohelpcharacterizechemicalexposureandassociatedbiologicaleffectsinthesameorganismunderenvironmentallyrealisticconditions.Thisapproachofcharac-terizingexposureandeffectsisconsistentwiththeUSEPAecologicalriskassessmentparadigm.Bivalvesareusefultestorganismsforin-situfieldbioassaysbecausethey(1)concen-trateandintegratechemicalsintheirtissuesandhaveamorelimitedabilitytometabolizemostchemicalsthanotherspecies,(2)exhibitmeasurablesublethaleffectsassociatedwithexpo-suretothosechemicals,(3)providepairedtissuechemistryandresponsedatawhichcanbeextrapolatedtootherspeciesandtrophiclevels,(4)providetissuechemistrydatawhichcanbeusedtoestimatechemicalexposurefromwaterorsediment,and(5)facilitatecontrolledexperimentationinthefieldwithlargesamplesizesbecausetheyareeasytocollect,cage,andmeasure(1,2)2.Theexperimentalcontrolaffordedbythisapproachcanbeusedtoplacealargenumberofanimalsofaknownsizedistributioninspecificareasofconcerntoquantifyexposureandeffectsoverspaceandtimewithinaclearlydefinedexposureperiod.Chemicalexposurecanbeestimatedbymeasuringtheconcentrationofchemicalsinwater,sediment,orbivalvetissues,andeffectscanbeestimatedwithsurvival,growth,andothersublethalendpoints(3).Althoughanumberofassessmentshavebeenconductedusingbivalvestocharacterizeexposurebymeasuringtissuechemistryorassociatedbiologicaleffects,relativelyfewassessmentshavebeenconductedtocharacterizebothexposureandbiologicaleffectssi...
