The Surber Design Bottom Sampler collects insects and other macroorganisms found on the bottom of moving streams at depths from 12 – 18″ (30 – 45 cm). It is used to determine larval insect population levels which are indicators of pollution in streams and watersheds. It is also used to monitor availability of food for fish, and to chart variation in aquatic life from different locations in the same stream. The durable netting filter is made of amber Lumite screening, available in two mesh sizes:
20 x 20 mesh Lumite screen, size of openings 965 microns (approximately 1 mm)
52 x 52 mesh Lumite screen, size of openings 280 microns
Closely woven white polyester is used for the top and side panels. Both fabrics are resistant to ultra violet light. Overall length of the sampling bag is 27″ (68 cm).
The rugged 12″ (30 cm) square frame is constructed of 1/8 x 1/2″ solid hard brass. It is placed on a stream bottom so that water flows into the 12″ square vertical portion of the frame and through the collecting bag, trapping organisms dislodged from the substrate. The upright portion of the frame unlocks for flat storage and portability. The sampler folds to approximately 12.5 x 12.5 x 2″ (32, 5cm), and weighs 4 lbs.
To prevent the sampler from sinking into a soft or uneven stream bottom with resulting loss of definition to the 12-square inch area, two metal bottom extension frames are available. Extension frames to support the sampler are 3″ and 6″ (7.6 and 15.2cm) in depth, fabricated of 22 gauge steel with heavy cadmium plating. The more appropriate extension is selected to support the sampler depending on composition of the substrate.