Processing the collected material

A synthesis of the protocol is provided on Figure 1.

  • Drying, weighting and storing

Back to the laboratory, the material has to be processed separately and as soon as possible.

CPOM: dry each type of CPOM in a dry oven for at least 12 hours at 60°C (but not more than 24h for leaves). Fresh material and fruits can be dried in a dry place during a week or so before being dried in the oven as above. Weight each type of CPOM (to the nearest g) to get the weight of each CPOM type per reach. Please avoid sun exposure during drying at a dry place.

Biofilm/algal mats: dry it in a dry oven for at least 12 hours at 60°C. Weight it (to the nearest g) to get the weight of biofilm/algal mats per reach.

Riverbed sediments: sieve the sediment through a 2 mm sieve and keep the fine fraction only. Dry the fine fraction in a dry place during a week, at least.

It would also be interesting to have the % moisture of the sediments to have an idea of the drying “severity”. To do so, keep ~50g of fresh sediments from the field and make 3 subsamples of ~15g, to have triplicates. Weight each triplicate to the nearest g, dry them in the dry oven 60°C for 24h and immediately reweight them to the nearest g. The weight difference by the initial weight gives the % moisture. Report these 3 values to the data spreadsheet. Although important, this step is optional and depends on each contributor time and willingness.

  • Preparing subsamples for shipping

CPOM: use the dry leave fraction only. Grind briefly the dry leaves by hand to obtain relatively fine particles and pass them into a sieve (0.5 cm mesh size). Leaf stems does not need to pass the sieve.

Prepare a subsample of the filtered material of ~60g of dried, ground leaves. If leaf mass is < to 60g, put everything you have. Use 2-3 Ziplock bags combined or a solid plastic container to prepare the subsample.

Biofilm/algal material: prepare a subsample of ~60g of dry and frozen biofilm/algal material. If the mass is < to 60g, put everything you have. Use 2-3 Ziplock bags combined or a solid plastic container to prepare the subsample.

Riverbed sediments: prepare one subsample of ~160g and one of ~40g of dry riverbed sediments. If the mass is < to 200g, put everything you have in one sample. Use 2-3 Ziplock bags combined or a solid plastic container to prepare the subsample.

  • Left over

Store the leftover of all material type in a dark and dry room (in case more material is subsequently needed).

 

 

Figure 1. Synthesis of the protocol representing one quadrat (1x1m) in which CPOM and river sediments are collected, another quadrat (20x20cm) in which biofilm/algal mat is collected and the following processing a shipping procedure. See 4.2. to define how many quadrats are needed and how to put them on the study reach.