A Critical Review of Recent Freshwater Periphyton Field Methods

Abstract

I review recently published research (1970–89) on freshwater periphyton, with emphasis on epilithon and epiphyton. Brushing syringe-samplers are recommended for sampling epilithon, due to their Sow cost, ease of use, and effective removal of periphyton from firm substrates. Methods for removing epiphyton include scraping, agitation, and chemical methods, and the choice of methods is influenced by morphology of the macrophyte. Artificial substrates for periphyton colonization (glass slides, styrofoam, clay tiles, and nutrient diffusing substrates) are also evaluated. Although the use of artificial substrates may decrease substrate heterogeneity and allow more complex experimental designs in studies of benthic herbivory, differences between the natural and artificial substrates may affect population size or behavior of herbivores. Methods for measuring primary productivity of periphyton (O2and14C methods) and recent advances in microelectrode technology that allow microscale measurements of productivity and several other parameters are discussed including key references for novice users. General recommendations include: (1) sampling periphyton on naturally occurring substrates rather than artificial substrates when measuring biomass, primary productivity or species composition; (2) using artificial substrates when experimental design dictates, but not ignoring their limitations; and (3) including accurate descriptions of methods to allow future comparisons between studies in different systems.