LaMotte 1061 User Manual

BRASS BOT TOM SAM PLING DREDGE

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CODE 1061

IN TRO DUC TION

The LaMotte Bottom Sampling Dredge, a modification of the well-known
Peterson dredge, provides a convenient method for collecting bottom
sediments. It is used for collecting bottom sediments which may contain
mud, sand, ooze, and gravel; however, it is not designed to collect samples
from rock bottoms. By using a bottom sampling dredge, a number of
different analyses can be made. Since the bottom sediments represent a
good area to find macroinvertebrates and benthic algae, the communities
of organisms living on or in the bottom can be easily studied
quantitatively and qualitatively. A chemical analysis of the bottom
sediments can be conducted to determine what chemicals are available to
the organisms living in the bottom habitat. Also, the structural
characteristics of the bottom may be examined and related to the
biological and chemical analysis. All of these different studies are made
possible through the use of a bottom sampling dredge.

Whenever samples of the bottom are taken, every effort must be made to
insure that the samples are truly representative of the whole area. Much of
this depends upon the judgment of the individual taking the sample and
their individual study objectives. In most cases, as many samples as
possible should be taken since one sample has no value statistically. The
time interval between sampling and analysis is not critical for a
mechanical or physical analysis, but immediate analysis is recommended
for both biological and chemical examinations.

IN STRUC TIONS FOR USE

The Bottom Sampling Dredge is shipped completely assembled. The
dredge has a bridle that reaches between the tips of the brass arms of the
dredge. Note that when the bridle is free (no tension upon it), the dredge
springs open. When the dredge is lifted by the bridle, the jaws of the
dredge snap shut.

A line is attached to the middle of the bridle to retrieve the dredge from
the bottom. Affix this line securely. The dredge must be allowed to fall
freely through the water. There must be no tension on the retrieving line
until the dredge has made contact with the bottom. There are holes in the
upper part of the collection chamber to let air escape from inside the
chamber, thus speeding the descent of the dredge. When the dredge has
made contact with the bottom, pull up on the retrieving line with a
smooth, steady hand over hand action without jerking the line, until the
dredge is above the water surface. Hold the dredge by the retrieving line or
by the middle of the bridle until you are ready to place the contents of the
dredge into a collecting container. If tension on the bridle is relaxed, the
jaws will spring open before the desired time and the contents will be lost.
A white porcelain or plastic pan provides an excellent receptacle for
examining the sample.

LaMOTTE COMPANY

Helping Peo ple Solve An a lyt i cal Chal lenges

PO Box 329 • Chestertown • Mary land • 21620 • USA

800-344-3100 • 410-778-3100 (Out side U.S.A.) • Fax [phone]

Visit us on the web at www.lamotte.com

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