Designation:D4558–02StandardPracticeforCollectingBenthicMacroinvertebratesWithDriftNets1ThisstandardisissuedunderthefixeddesignationD4558;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Driftnetsareusefulforcollectingmacroinvertebratesthatactivelyorpassivelyenterthewatercolumnorthataredislodgedfromthesubstrate;naturallyorbystress.Theyareparticularlywell-suitedforsynopticsurveysbecausetheyarelightweightandeasilytransported.1.2Thousandsoforganisms,includinglarvaeofstoneflies,mayflies,caddisflies,andmidgesandotherDiptera,maybecollectedinasamplingperiodofonlyafewhours.1.3Thedriftnetefficientlycollectsorganismsoriginatingfromalltypesofsubstratesandawidespectrumofmicrohabi-tatsinlotic(flowing)waters.1.4Thedeviceisrestrictedtoflowingriversorstreamswithacurrentvelocityofmorethan0.05m/s.1.5Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:D4387GuideforSelectingGrabSamplingDevicesforCollectingBenthicMacroinvertebrates2D4556GuideforSelectingStream-NetSamplingDevicesforCollectingBenthicMacroinvertebrates23.SummaryofPractice3.1Thetypicaldriftnetconsistsofabagofnylonornylonmonofilament;avarietyofmeshsizescanbeuseddependingontheobjectivesofthestudy.TheU.S.StandardNo.30(0.595-mmmeshopenings)netisoftenusedforcollectingmacroinvertebrates.3.2Theframetypicallyconsistsofa0.045-m2(15by30-cm)brassrodstructureanchoredintothestreambedbyapairofsteelrods.3.3Cableclampsareusedtosecurethenetstotherods.3.4TheaveragevolumeofwaterpassingthroughthenetisdeterminedbymeasuringthewatervelocityatthemouthofthedriftnetwithaPygmyPriceCurrentMeter3(orequivalent)sever...
