Concept and design of a substrata container for sampling periphyton

Limitations in available field sampling methodology and substrata sampler design criteria, to reduce retrieval losses of periphyton, are discussed. The process of retrieving submerged substrates is defined as comprising two distinct operations—(1) in situ substrata encapsulation or containment and (2) subsequent withdrawal of contained surfaces through the water column. A cylindrical closing container which effects no appreciable water disturbance on closing is described. A minimal difference was found between water movement across sampling surfaces contained in the closing system compared with traditional open-type substrata exposure devices. Comparative community sampling studies between open and closing containers in an oligotrophic lake indicate the closing containment system to be an acceptable method for studying periphyton.