A simple plankton splitter with i note on its reduced subsampling variance

Abstract

A simple compartment-type devicefor splitting plankton samples is described which can split small volumes of liquid with an accuracy of about 1% and provides unbiased subsamples of the plankton in suspension. The variance generated by the device is much less than expected from binomial theory and remains relatively constant over a range of sample sizes. Possible reasons for this characteristic are discussed, and an empirical estimate of the reduced variance is used to calculate narrower confidence intervals.