A Quantitative Method for the Collection and Measurement of Stream Periphyton1

Two methods for the collection and estimation of stream periphyton production are presented. The periphyton was collected on 1.4 dm 2 plexiglass plates attached to a horizontal crossbar. The crossbar was supported by a vertical post driven into the stream bottom or supported by a concrete block. The plates were removed from the stream and the established population estimated by determining the absorbency of the ethanol‐soluble phytopigments and by gravimetric procedures. A reliable estimate of the population can be made from the phytopigment absorbency values if the latter are corrected for deviations from the absorbency:concentration relationship and if the substrata are removed from the stream before the growth is too profuse. Confidence limits are given for the phytopigment density:weight of organic material relationship.