Procedure:
• Gently remove the tray from the stream bed moving it downstream with the current as
you lift it up. Warning: the trays are very heavy when full of water.
• Keep the tray close to horizontal while draining, especially if there is any chance of
material becoming detatched from the filter papers.
• When the sampler starts to clear the water, take a note of anything that might influence
the periphyton communities and thus effect interpretation of the results. Write these
down once on the river bank. Things to observe might include the amount of silt
accumulated on the slides or substrates, any debris such as leaves, twigs or macrophyte
stems that have caught on the sampler and might have brushed against the sampling
surfaces or influenced local flow paths.
• Count any invertebrates on each filter paper to the lowest taxonomic level that you can
clearly recognise. These data are often very useful for interpreting the enrichment
results and might provide another useful assessment of water quality (see the SHMAK
rapid bioassessment protocol for a general grouping of invertebrates based on their
pollution tolerances and ease of identification: Biggs et al. 1998c).
• Remove the lid and carefully slide off the plastic rings.
• Starting at the upstream left hand corner (the first N treatment), remove the whole filter
paper from the agar substrate.
• Drain off as much water as possible.