Volunteer programs that want to do wetland bioassessments will need to work closely with ecologists in their region. Bioassessment techniques are based on the pioneering work of James Karr and others who developed biological indicators for stream health. The underlying idea is that the condition of living organisms in an aquatic system will reflect the extent of disturbances to that system. Such measurements are called metrics, and they are chosen because they have been found to be reliable indicators of health in a given ecosystem. The traps are left in the wetland for 1 to 3 days.
Organisms swim into the funnel opening and are unable to find their way back out.
This is important because tape or clamps increase the trap's visibility. Wik's trap is nearly invisible when viewed straight on. Wik uses a hot wire foam cutting tool to make four slits near the bottom of the funnel. The slits cause the plastic to curl slightly, allowing the funnel to be snapped securely into place. The position and length of the slits are critical, as is the amount of heat.