ASTM E1201-87(2012)

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Designation: E1201 − 87 (Reapproved 2012)
Standard Practice for
Sampling Zooplankton with Conical Tow Nets
This standard is issued under the fixed designation E1201; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.4 They are clogged by grass beds, coelenterates, and
filamentous algae.
1.1 This practice covers the procedure for obtaining quali-
3.2.5 When used with a flowmeter, they collect only quali-
tative samples of a zooplankton community by use of conical
tative samples, or semiquantitative samples.
tow nets. Nets will collect most zooplankton, but some forms
3.2.6 When sampling discrete depths using a horizontal tow,
will avoid nets.
the sample can be contaminated from other depths during the
1.2 This standard does not purport to address all of the
deployment and retrieval of the samples if opening and closing
safety problems, if any, associated with its use. It is the
devices are not used.
responsibility of the user of this standard to establish appro-
3.3 There are several special considerations that shall be
priate safety and health practices and determine the applica-
observed when using conical tow nets. They are:
bility of regulatory limitations prior to use.
3.3.1 Conical tow net samplers are designed to be towed at
speedslessthanthreeknots;however,greaterspeedshavebeen
2. Summary of Practice
usedforthelargernetswithaconcomitantincreaseincapture.
2.1 The net is attached to a tow line and towed at the desired
3.3.2 A conical tow net 0.5 m in diameter or larger shall be
depth, using a cable depressor if necessary. After a specified
used to reduce avoidance by organisms.
distance or period of time, the net is retrieved and the captured
3.3.3 The nets shall be washed frequently and inspected for
zooplankton are removed from the net. The zooplankton may
pin-size holes, tears, net deterioration, and other anomalies.
be preserved as dictated by the objective of the study.
3.3.4 Nets should be allowed to dry while suspended full
length in air and in subdued light prior to storage.
3. Significance and Use
3.3.5 Lower catches per sample may result when collections
3.1 Theadvantagesofusingconicaltownetsareasfollows:
are made during the day. These are particularly noted in the
3.1.1 They are relatively inexpensive and highly versatile in
larger zooplanktons.
a variety of inland, estuarine, coastal, and marine waters.
3.1.2 They can be used from a small or large powered boat
4. Procedure
with a minimum of auxiliary equipment.
4.1 The conical net samplers are designed to be towed at
3.1.3 They can be used to collect qualitative samples and
speeds of approximately three knots. However, greater speeds
semiquantitative samples when fitted with a flowmeter and
of up to five knots have been used with a concomitant increase
even better samples when fitted with a companion meter on the
in organisms captured per unit volume of water filter.
outside of the hoop to monitor filtering efficiency.
4.2 Select the bridle arrangement carefully. The most com-
3.2 The disadvantages of conical tow nets are as follows:
mon arrangement is a three-point attached bridle resulting in
3.2.1 When equipped with a flowmeter they require fre-
considerable net avoidance. An attachment procedure result-
quent maintenance including calibration and, in some types,
ing in no obstruction of the mouth is preferred and can be
lubrication.
accomplished by using a simple gimbaled hoop arrangement,
3.2.2 They are effective only where drawn through a stream
with a depressor at the bottom of the tow line.
of water having considerable thickness. They are not suitable
4.3 Proper placement of the flowmeter within the conical
for collecting samples from a small or restricted region.
3.2.3 They are not suitable for collecting in very shallow net mouth is crucial for sample quantification. In order to
water.
Schwoerbel, J., Methods of Hydrobiology (Freshwater Biology), Pergamon
This practice is under the jurisdiction of ASTM Committee D19 on Water and Press, New York, NY, 1968, p. 200.
is the direct responsibility of Subcommittee D19.24 on Water Microbiology. Clutter, R. I., andAnraku, M., “Avoidance of Samplers,”UNESCOMonograph
Current edition approved Dec. 1, 2012. Published December 2012. Originally on Oceanographic Methodology, No. 2, 1968, pp. 57–76.
approved in 1987. Last previous edition approved in 2004 as E1201 – 87 (2004). UNESCO, “Zooplankton Sampling,” Monographs on Oceanographic
DOI: 10.1520/E1201-87R12. Methodology, Unipub, Inc., New York, NY, 1968, p. 174.
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