ASSIMILATION OF ORGANIC MATTER BY ZOOPLANKTON1

Abstract

A method for direct measurement of percentage of assimilation of organic matter by zooplankton that does not require the quantitative recovery of feces and can be adapted for use in the field as well as in laboratory investigations is described. If it is assumed that only the organic fraction of the food ingested by a zooplankton animal is affected by the digestive process, it can be shown that percentage of utilization is defined as urn:x-wiley:00243590:media:lno19661130338:lno19661130338-math-0001 where F ′ is the ash‐free dry weight: dry weight ratio (fraction of organic matter) in the ingested food, and E’ is the same ratio in a representative sample of feces. The method compares favorably, as a measure of assimilation, with direct measurement of the quantity of organic matter lost from food during passage through the digestive tract.