Alternative live sorting procedure
Alternatively to laboratory processing and sorting, the sample may also be sorted in the field.
The live sorting procedure was developed in accordance to the laboratory sorting and includes the following steps:
The collected sampling units are transferred into one or more sorting trays.
The complete sample volume may be reduced to an appropriate amount of sampling material and individuals by subsampling.
The number of individuals belonging to discrete, recognizable taxa is estimated using an abundance scale and noted in the field protocol.
Three voucher specimens of every distinct taxon, which is recognisable in the field, are collected. Of the remaining taxa a predetermined minimal number is collected for further identification in the laboratory.
A detailed description, including exceptional cases such as partial-wadable rivers, is given in the river assessment manual” (only in German).