ASTM_D_4558_-_02.pdf

Designation:D 4558 02Standard Practice forCollecting Benthic Macroinvertebrates With Drift Nets1This standard is issued under the fixed designation D 4558;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 Drift nets are useful for collecting macroinvertebratesthat actively or passively enter the water column or that aredislodged from the substrate;naturally or by stress.They areparticularly well-suited for synoptic surveys because they arelight weight and easily transported.1.2 Thousands of organisms,including larvae of stoneflies,mayflies,caddisflies,and midges and other Diptera,may becollected in a sampling period of only a few hours.1.3 The drift net efficiently collects organisms originatingfrom all types of substrates and a wide spectrum of microhabi-tats in lotic(flowing)waters.1.4 The device is restricted to flowing rivers or streams witha current velocity of more than 0.05 m/s.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 4387 Guide for Selecting Grab Sampling Devices forCollecting Benthic Macroinvertebrates2D 4556 Guide for Selecting Stream-Net Sampling Devicesfor Collecting Benthic Macroinvertebrates23.Summary of Practice3.1 The typical drift net consists of a bag of nylon or nylonmonofilament;a variety of mesh sizes can be used dependingon the objectives of the study.The U.S.Standard No.30(0.595-mm mesh openings)net is often used for collectingmacroinvertebrates.3.2 The frame typically consists of a 0.045-m2(15 by30-cm)brass rod structure anchored into the stream bed by apair of steel rods.3.3 Cable clamps are used to secure the nets to the rods.3.4 The average volume of water passing through the net isdetermined by measuring the water velocity at the mouth of thedrift net with a Pygmy Price Current Meter3(or equivalent)several times,and recording the total time the drift net is set inthe water column.Several readings are taken,and the mean isused.3.5 The efficiency of the net is determined by the simulta-neous measurement of the water velocity passing by the setdrift net.3.6 The drift net frame can be fitted anteriorly with a mouthreducing rectangular plexiglass enclosure(Rutter and Ettinger(1)4)to increase filtration efficiency.3.7 The type of drift net and mesh size utilized will dependon the objectives of the study and the physical characteristicsof the flowing water.3.8 Alternatives to the typical drift net include the water-wheel drift sampler(Pearson and Kramer,(2)which might beuseful in large rivers or streams which can be reached byautomobile.3.9 An automatic drift sampler(Muller,(3)can be con-structed that eliminates the need for an attendant at thesampling site during collection of as many as eight consecutivesamples.3.10 A modified emergence-trap drift sampler(Mundie,(4);Cushing,(5)is useful in streams with extremely high drift,where water is very turbid,or where a long sampling period isdesired without clogging.3.11 The drift collection usually represents a wide spectrumof the habitats found in a stream.3.12 A benthic sample shows only what taxa were existingin the particular area(usually some fraction of a square metre,etc.)that was sampled.3.13 The great variation among benthic samples,even in alimited area,illustrates the necessity of several samples and theinfluence of selecting the collecting sites.3.14 One drift sample might be adequate for collecting themajority of invertebrate taxa in a stream reach,whereas a largenumber of benthic samples would be needed to cover thevariety of bottom habitats even in a uniform reach of thestream.1This practice is under the jurisdiction of ASTM Committee E47 on BiologicalEffects and Environmental Fate and is the direct responsibility of SubcommitteeE47.03 on Sediment Assessment and Toxicology.Current edition approved April 10,2002.Published July 2002.Originallypublished as D455885.Last previous edition D455885(1995)2Annual Book of ASTM Standards,Vol 11.05.3The Pygmy Price Current Meter,or its equivalent,has been found satisfactory.Available from Kahl Scientific Instrument Corp.,P.O.Box 1166,El Cajon,CA92022-1166.4The boldface numbers in parentheses refer to the list of references at the end ofthis practice.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superceded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.3.15 Quantitative benthic sampling is seldom ex