in conditions where they interact, resulting in a CaCO3 precipitate. How-ever, this conclusion is not supported by field surveys of lake whiting events in which the ingestion of CaCO3 particles caused only a 16% de-crease in cladoceran feeding rates (Vanderploeg et al., 1987). A possible explanation of this contradiction may lie in differences in the rate of cal-cite production between lab and field studies (and thereby Ca2+ and CO23− concentrations). After calcite precipitation has begun, the precip-itation rate is proportional to the product concentrations of Ca2+ and CO23− in solution (Nancollas and Reddy, 1971).