There are many designs of settlement samplers and their construction is limited only by the imagination. Most are constructed of PVC and it appears that the settling mussels have a preference for tube or cylinder samplers rather than plate samplers. Mussels also gravitate toward the settlement of gray or darker PVC rather than white. Perhaps this is due to their avoidance of light.
Density is also affected by the use of different materials (see Claudi and Mackie 1994). The following materials have higher settlement intensities: vinyl and plastics, pressure-treated wood, iron, steel, aluminum, stone, concrete, fiberglass, polypropylene, and asbestos. The following materials were not preferred: silicone, brass, copper, and galvanized metals.
Any artificial substrate should be deployed at least 2 weeks prior to the spawning season of the zebra mussel. This early deployment allows biofilm to build up on the substrate, making settlement more attractive. Without this biofilm it will be unlikely that adequate mussel settlement and colonization will be achieved.
Settlement rates will also be affected by the way the plate is hung. A vertical plate has proven to be the best deployment. Mussels may also tend to colonize the corners and edges of plates, forming druses or clumps.
Sleds with settlement racks hold rows of "coupons,” which are other forms of artificial solid substrates. These sleds and settlement racks are deployed and the coupons colonize with mussels. The coupons, once the desired stage of settlement has occurred, are easily removed and studied in lab testing or used for quantitative analysis.
Monitoring of Settled Juveniles and Adults