1m 



10 cm 



o 





Figure l.-Opening/closing epibenthic sampler: A) sled frame; 

 B) box with door closed; C) detail, side view of shoe, hinge, and 

 shoe adjustment device; D) box with door open showing 

 flowmeter and springs for closing door; E) schematic net 

 attachment, solid line is box wall, two cross hatched lines are 

 collars of coarse mesh liner (inner) and plankton net (outer), open 

 bars are stainless steel straps with bolts; F) safety collar insert 

 with rings for cable attachment protruding through collar and 

 PVC cod end with threaded teflon plug; G) schematic lateral view 

 showing sled, box, net, and canvas chafing gear. 



ment points for affixing the box to the sled were 

 made from 3.8-cm round stock, tapped to 9.5 mm 

 and reinforced with 5.1 x 0.48 cm flat stock. The 

 box is fastened to the sled by four stainless steel 

 bolts (0.95 X 3.8 cm). 



The door of the box was made from mild steel 

 plate (109.2 x 48.3 x 0.48 cm) and is hinged with a 

 6.4-mm stainless steel rod at five points along the 

 bottom. The shoe which opens the door upon 

 contact with the sea floor is triangular shaped 

 (33.0 X 50.8 X 0.48 cm) and is hinged to allow 

 adjustment, depending on the distance the box is 

 set off the bottom (Figure IC). Four large springs 

 (5.1 X 22.9 cm), attached internally, pull the door 



shut when the sled leaves the sea floor (Figure ID). 

 The door-to-shoe surface area ratio is about 5:1, so 

 that water pressure effectively holds the door shut 

 on descent and ascent (Figure IB). A TSK 

 flowmeter^ is mounted in the middle of the mouth 

 by a brace (1.9 x 0.48 cm). The nets are attached to 

 the rear of the box by sandwiching them between 

 stainless steel straps (5.1 x 0.48 cm) bolted 

 together at 7.6-cm intervals (Figure IE). The inner 

 strap has 6.4-mm stainless steel bolts welded to it, 

 while the outer strap has holes drilled to corre- 

 spond to the bolts in the inner strap, as well as the 

 holes in the box and net collars. The entire sled, 

 except for the springs and stainless steel fittings, 

 was hot dipped galvanized. 



The plankton net was made of 571-jum mesh 

 nylon monofilament. The filtering area to mouth 

 area ratio is 9:1. The "cylinder'V'cone" net had a 

 total mesh area of 7.7 m^, with 2.6 m^ in the cone 

 and 5.1 m- in the cylinder. The collars were made 

 of plastic coated nylon webbing. The cod end is a 

 30.5-cm piece of 10.2 cm outside diameter schedule 

 80 polyvinyl chloride (PVC) pipe, with a threaded 

 teflon plug for removing the sample. There is also 

 a stainless steel insert above the cod end fitted 

 with two rings protruding through slits in the 

 collar, for attachment of safety wires from the 

 sled frame to the cod end, in the event a large 

 amount of sediment was retained (Figure IF). 

 Overall length of the net including collars and cod 

 end is 5.1 m (Figure IG). A small coarse mesh net 1 

 m deep (2.5-cm stretched mesh) was mounted 

 inside the plankton net (see Figure IE) to catch 

 any large animals or objects and prevent them 

 from damaging the plankton net or the sample in 

 the cod end. A piece of heavy canvas (1.2 x 3.7 m, 

 no. 4 duck) was attached to the rear of the sled by 

 shackles, to protect the plankton net from chafing 

 on the sea floor (Figure IG). 



Epibenthic Sampler Operation 



Because of its size and weight (ca. 150 kg in air) 

 the epibenthic sampler can only be used from a 

 vessel with a suitable trawl winch; in the present 

 study the 24.4-m RV Cayuse with a 9.5-mm 

 diameter trawl wire was used. The sled was fas- 

 tened to the trawl wire with a ball bearing swivel 

 and a 3-m bridle of 9.5-mm wire attached to the 



2Tsurumi-Seiki Kosakusho. Reference to trade names does not 

 imply endorsement by the National Marine Fishenes Service, 

 NOAA. 



995 



