Potential zooplankton metrics. The recommended approach is to sample 4 to 6 times during a growing season to obtain seasonal averages. A zooplankton sample can be collected in approximately 10 to 30 minutes in the field. Identification and counting of 100 to 200 organisms requires approximately 1 to 2 hours. Six samples in a growing season per lake thus requires six trips and 6 to 12 laboratory hours.
Diatoms are often the group of choice among periphytic algae.
In addition, periphyton are affected by the physical and chemical characteristics of their substrate. Like phytoplankton, periphyton are subject to changing water chemistry and seasonal succession. Several sampling periods may be necessary to characterize lake periphyton. Level of Effort Analysis of a periphyton sample requires 2 to 6 hours, similar to diatoms and phytoplankton. Responsive metrics are shown in Figure 6-1.