Appendix 1. Algal Bioassay Methodology to Determine Pond Fertilization Requirements

Several liters of subsurface pond water are collected in a prerinsed container or bucket. It is better to collect the water soon after dawn, before ambient N, P, and C are stripped from the water column by phytoplankton through photosynthetic activity. The method described here uses 500-ml pondwater subsamples for individual treatment determinations, but this volume and the corresponding nutrient spike volumes can be scaled up or down if more convenient. Larger sample volumes may be preferable, however, in that they reduce potential sources of variability from contamination and/or bottle effects (Mitchell and Malthus, 1984).