1、Designation: E1201 87 (Reapproved 2012)Standard Practice forSampling Zooplankton with Conical Tow Nets1This standard is issued under the fixed designation E1201; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the procedure for obtaining quali-tative samples of a zooplankton community by use of conicaltow nets. Net
3、s will collect most zooplankton, but some formswill avoid nets.1.2 This standard does not purport to address all of thesafety problems, 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 applic
4、a-bility of regulatory limitations prior to use.2. Summary of Practice2.1 The net is attached to a tow line and towed at the desireddepth, using a cable depressor if necessary. After a specifieddistance or period of time, the net is retrieved and the capturedzooplankton are removed from the net. The
5、 zooplankton maybe preserved as dictated by the objective of the study.3. Significance and Use3.1 The advantages of using conical tow nets are as follows:3.1.1 They are relatively inexpensive and highly versatile ina variety of inland, estuarine, coastal, and marine waters.3.1.2 They can be used fro
6、m a small or large powered boatwith a minimum of auxiliary equipment.3.1.3 They can be used to collect qualitative samples andsemiquantitative samples when fitted with a flowmeter andeven better samples when fitted with a companion meter on theoutside of the hoop to monitor filtering efficiency.3.2
7、The disadvantages of conical tow nets are as follows:3.2.1 When equipped with a flowmeter they require fre-quent maintenance including calibration and, in some types,lubrication.3.2.2 They are effective only where drawn through a streamof water having considerable thickness. They are not suitablefor
8、 collecting samples from a small or restricted region.3.2.3 They are not suitable for collecting in very shallowwater.3.2.4 They are clogged by grass beds, coelenterates, andfilamentous algae.3.2.5 When used with a flowmeter, they collect only quali-tative samples, or semiquantitative samples.3.2.6
9、When sampling discrete depths using a horizontal tow,the sample can be contaminated from other depths during thedeployment and retrieval of the samples if opening and closingdevices are not used.3.3 There are several special considerations that shall beobserved when using conical tow nets. They are:
10、3.3.1 Conical tow net samplers are designed to be towed atspeeds less than three knots; however, greater speeds have beenused for the larger nets with a concomitant increase in capture.23.3.2 A conical tow net 0.5 m in diameter or larger shall beused to reduce avoidance by organisms.23.3.3 The nets
11、shall be washed frequently and inspected forpin-size holes, tears, net deterioration, and other anomalies.3.3.4 Nets should be allowed to dry while suspended fulllength in air and in subdued light prior to storage.3.3.5 Lower catches per sample may result when collectionsare made during the day. The
12、se are particularly noted in thelarger zooplanktons.4. Procedure4.1 The conical net samplers are designed to be towed atspeeds of approximately three knots. However, greater speedsof up to five knots have been used with a concomitant increasein organisms captured per unit volume of water filter.34.2
13、 Select the bridle arrangement carefully. The most com-mon arrangement is a three-point attached bridle resulting inconsiderable net avoidance.4An attachment procedure result-ing in no obstruction of the mouth is preferred and can beaccomplished by using a simple gimbaled hoop arrangement,with a dep
14、ressor at the bottom of the tow line.4.3 Proper placement of the flowmeter within the conicalnet mouth is crucial for sample quantification. In order to1This practice is under the jurisdiction of ASTM Committee E47 on BiologicalEffects and Environmental Fate and is the direct responsibility of Subco
15、mmitteeE47.01 on Aquatic Assessment and Toxicology.Current edition approved Dec. 1, 2012. Published December 2012. Originallyapproved in 1987. Last previous edition approved in 2004 as E1201 87 (2004).DOI: 10.1520/E1201-87R12.2Schwoerbel, J., Methods of Hydrobiology (Freshwater Biology), PergamonPre
16、ss, New York, NY, 1968, p. 200.3Clutter, R. I., andAnraku, M., “Avoidance of Samplers,” UNESCO Monographon Oceanographic Methodology, No. 2, 1968, pp. 5776.4UNESCO, “Zooplankton Sampling,” Monographs on OceanographicMethodology, Unipub, Inc., New York, NY, 1968, p. 174.Copyright ASTM International,
17、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1obtain an average velocity of water within the net, place themeter at a point one-third of the diameter of the mouth of thenet.4.4 The type and mesh size of the netting used is veryimportant because the most common t
18、ype of net available is asimple, interlocking monofilament mesh. Although there is atendency to adopt the smallest mesh size possible, there is aliability with small mesh sizes in reducing the collectingefficiency of the gear. In addition to the initial reduction inefficiency by the nature of the sm
19、all mesh, the clogging rate ofthe gear is accelerated. A 103-m net has been demonstrated tofall below 85 % efficiency within the first minute oftowing.4Table 1 indicates the types of organisms present in thezooplankton from various habitats and the size range of eachthat is necessary for determining
20、 the mesh necessary toimplement a sampling program.4.5 The length of the net applied to these conical net framesis crucial. It is widely accepted that a mouth diameter to lengthratio of 1:5 is used to increase filtration efficiency of the gear.TABLE 1 Size of Common ZooplanktonASpeciesFresh MarineHa
21、bitat Size Range Habitat Size RangeProtozoans (single cells) 6 to 1,000 2.0 mmCiliophora (ciliated single cells) few fresh 22 to 600 Coelenterata few fresh (Hydras) 1.0 mm statoblastsChaetognatha (arrowworms) high salinity up to 40 mmAnnelida (segmented worms)Oligochaeta most fresh 0.5 to 5 mm very
22、fewPolychaeta few fresh most spp. small except Nereis up to 50 cmHirundinea most fresh (standing adults 5 mm to 45.7 cm few marinewaters)ArthropodaCrustaceaBranchlopoda most fresh 3 mm to 30 mm some marine 10 mmCladocerans most fresh(lenthic waters)up to 3 mm; 0.2 to 18.0 mm0.6, 0.3, 0.4 mm; 1.7, 1.
23、0, 0.9 mmfew marinemost estuarine/marinein top ofbottom sedimentOstracodaCopepodaCalenoida nauplius4.0 mm 0.5 to 10.0 mmCyclopoida nauplius3.0 mm 0.5 to 1.0 mmHarpacticoid nauplius1.0 mm 0.5 to 1.0 mEctoparasites some fresh 5 to 25 mm some estuarine 5.5 to 25 mmCirripedia estuarine/marine:naupliiMys
24、idacea few in cold lakes 8 to 30 mmAmphipoda some fresh 5 to 25 mm 5 to 30 mmDecapoda some associated withdebris15 to 200 mm 2.0 mm to 20 to40 cmInsecta (aquatic) most freshMolluscaGastropodaadults 2 to 70 mm 8 to 80 mmtrochophorePelecypoda some fresh adults 2 to 250 mm most have freeswimming larvae
25、EchinodermataFish eggs/larvae eggs 0.75 to 3 mm 400 to 505 larvae 1.5 mmASage, L. E., “Zooplankton,” In: Methods for the Assessment and Prediction of Mineral Mining Impacts on Aquatic Communities: A Review and Analysis, Fish WildlifeService/Office of Biological Services, Vol 78/No. 30, April 1978, p
26、p 5565.E1201 87 (2012)24.6 Collect the sample during the night, again to minimizeavoidance of the larger adult forms.4.7 Depending on the mesh net employed and the density ofthe zooplankton and detritus in a particular ecosystem, keep thelength of tow to two minutes or less to avoid undue cloggingwh
27、ich would result in drastically altered filtration efficiencyadversely affecting the quantification of the sample.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly adv
28、ised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either
29、 reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. I
30、f you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Indivi
31、dual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E1201 87 (2012)3
