Pot scrubber sampler
Target life cycle stage: Settling and floating juveniles
Sampling gear: Scouring pad or "pot scrubber" sampler as described by Martel in Marsden (1992), filamentous netting (bridal veil)
Recommended habitat(s): Especially suitable for flowing water
Type of data collected: Qualitative and quantitative
Deployment protocol: Deploy samplers below the photic zone or in the shade. There are two commonly used filamentous substrate samplers that can be easily constructed.
1) The "pot scrubber" samplers are built by gluing two plexiglas strips to either end of a fine mesh fiber scouring pad as per Martel (1992). Swivels are then attached to the plexiglas and a series of samplers may be deployed on a weighted line with the last at least 0.5 m above the bottom and the first at least 0.5 m below the surface.
2) The "bridal veil" samplers consist of a piece of nylon netting (bridal veil) that is rolled or crumpled into a wire or plastic mesh cylinder and capped at both ends with additional mesh. One end may be glued into place using hot glue, but the other should be easily removed. The cylinder is then deployed on a weighted line below the photic zone, but above the substrate.
High collection rates can be observed within 24-72 hr of deployment. After a given time interval, samplers are recovered and kept moist and cool prior to analysis or are submerged in preservative for later analysis.
Extraction of juveniles from the pot scrubber sampler:
Examine the plexiglas portion of the sampler for juveniles prior to their extraction from the scouring pad. To extract the juveniles from the pad, hold over a collecting vessel and wash each pad with a stream of pressurized tap water. Rinse each pad three times for approximately 30 sec per rinse. Filter the rinse water twice using a 500-µm mesh sieve. After extraction, examine both the scouring pad and the sample under a dissecting microscope.
Extraction of juveniles from the bridal veil cylinder sampler:
Remove filamentous netting from cylinder housing. Place netting in large bucket, rinse thoroughly until netting is clean. Filter rinse water through a 500-µm mesh sieve. Examine the material in the sieve for the presence of juveniles. The samples can be quantified (number per square meter). Under the microscope, measure the size of the nylon cylinders forming a single mesh. Calculate surface area of the four cylinders, and count the number of mesh squares in the material. This provides the number of juveniles/square meter. Keep in mind that settled juveniles tend to remain on the material.
Advantages: Useful qualitative or quantitative technique, especially in areas where larger samplers are likely to be disturbed. Earliest detection of settling events over short periods of time.
Disadvantages: Samplers are susceptible to disturbance and vandalism even with a short deployment interval and small size. Clogging of substrates is common in areas of high suspended solids.