QUANTITATIVE MULTIPLE OPENING- AND-CLOSING 
PLANKTON SAMPLERS 
by DR. ALLAN W.H. BE 
Lamont Geological Observatory 
(Columbia University) 
Palisades, New York 
ABSTRACT 
Two quantitative opening-and-closing 
plankton samplers are described for serial 
sampling of zooplankton in the upper 1000 
meters of water. The Moltiple Plankton Sampler 
(MPS) is designed for towing at three depth 
ranges (0-100 m; 100-250 m; and 250-500 m) in 
the upper 500 meters, and the Bathypelagic 
Sampler (BPS) is intended for simltaneous 
towing in the more sparsely populated 500-1000 m 
depths. 
THEORY OF OPERATION 
The two samplers were specifically designed 
for: 
a. filtering large volumes of water (10 m?/min. 
or more) through horizontal and oblique 
towing; 
b. reliable opening-and-closing actions at the 
mouths of the nets, without fear of catch 
loss or contamination; 
ec. obtaining a bathymetric series of plankton 
samples at accurately predetermined depth 
levels by means of a fool-proof release 
mechanism; and 
d. reducing ship's time operation by the use of 
multiple nets in single lowerings. 
It should be emphasized that the present 
samplers require towing at 2 to 4 knots with 
wire angles of 30° to 50°. Thus, they are 
primarily intended for deep bathymetric studies 
of zooplankton and are in a different_category 
from the high-speed plankton samplersl,2,3,4, 
which are towed mainly in the 0-100 m, near- 
surface zone. The ability of horizontal and 
oblique towing of the present samplers is 
considered an important improvement over the 
other mi1tiple Pace samplers requiring 
vertical hauls.7,6,7 
Multiple Plankton Sampler 
The MPS is designed to take three samples 
and allows opening-and-closing actions of three 
separate plankton nets. Its operation depends 
upon the following components: 
a. +mx 3m square fiberglass frame containing 
three pivoting rods with a common axis of 
rotation in one corner. Three one-half 
meter nets are attached to the rods and to 
the corner opposite the common axis in such 
a manner that each net may be folded 
(closed) and/or opened by 90°-rotation 
of its corresponding pivoting rod (the 
rotational force upon the rods is provided 
by three elastic cords, attached to the 
frame's exterior and the outwardly extending 
ends of each pivoting rod); 
b. pressure-actuated, piston-type release mech- 
anism with three release levers; and 
ec. three flowmeters. 
At the start of the tow all three rods are 
fastened by thin cables to each of the release 
levers, which in turn are held in cocked 
position by the piston stem of the release 
mechanism. The "shallow" net is open when 
lowered and ready to fish on the way down, while 
the other two nets are folded. 
At the first selected depth level (e.g. 
100 m), the piston stem will have travelled 
past and released the upper lever -- thus 
triggering a 90°-rotation of the first rod and 
closing the first or "shallow" net while 
simultaniously opening the second net. At the 
end of the second depth interval (e.g. 250 m), 
the second net is closed and the third net is 
opened simultaniously. The closing of the 
third net at 500 m depth concludes the MPS 
operation. 
"Superior numbers refer to similarly numbered references at the end of this paper." 
