Supplementary Material

Table S1. Characteristics of volunteer groups (student classes), according to the scholar degree (covering degrees from the 5th to the 12th years of scholarity), mean age of the students, number of teachers involved and number of students for each class. A few schools merged different classes in the same group; those cases correspond to two to three scholar degrees or two to three mean ages.

Degree Mean Age Teachers Students 5th 11 3 40 12th 17 3 12 5th 11 2 20 5th 12 2 27 5th 11 3 25 7th 12 3 17 8th 13 2 20 8th 13 1 39 9th,11th,12th 16 3 66 10th 15 3 23 8th 13 1 26 10th 15 3 38 8th 13 2 12 8th 13 2 14 8th 13 1 23 9th 14 1 6 8th 13 3 23 10th 15 1 11 9th 14 1 4 7th 12 3 24 8th 13 3 23 5th .10, 11 3 20 8th 13 3 23 7th,8th 13 3 12 8th 13 3 25 10th 15 3 25 10th 15 3 25 10th 15 2 25 10th 15 2 25 11th,12th 16, 17 3 19 11th,12th 16, 18 3 19 11th,12th 16, 17 3 19 11th,12th 16, 17 3 19 8th 13 3 15 8th 13 3 23 5th .10, 11 1 20 Table S2. Categories in the field form distributed by the four main descriptors.

Settlements on the State of Stream Land Use Stream the Water Characteristics tourism mures none perceptible flow natural golf tubes laminar flow intermediary camping spring turbulent flow altered agriculture well no smell Pasture channel mud smell farm mill waste smell forest dam clean water industry brown water waste water treatment plant black water (wwtp) constructions soft green water road hard green water

Table S3. Macroinvertebrate surrogate groups and corresponding ecological quality class.

Vernacular Name Scientific Name Ecological Class Quality Fresh water worms Oligochaeta Bad quality (Class 2) Midge blood larvae Planaria Leach Hirudinea Freshwater snail Freshwater mussel Bivalvia Freshwater slater Moderate quality (Class 3) Dragonfly Anisoptera Damselfly Zygoptera Beetle Coleoptera Black-Fly larvae Simuliidae Fly larvae Diptera Freshwater scud Amphipoda Shrimps and crabs Crustacea Mayfly Ephemeroptera Good quality (Class 4) Caddisfly Trichoptera Alderfly larvae Megaloptera Stonefly Plecoptera High quality (Class 5)

Figure S1. The flow key to identify the surrogate taxa is presented at figure below.

How to use this flow dichotomic identification key 1. Start at arrow 1 2. Identify the distinctive characters (in solid rectangular shapes and highlighted in bold) 3. Choose one of the two options (in dashed rectangular shapes) 4. Follow the arrows until you get a taxon (grey light rectangular shapes)

Tables S4 and S5: Calculation of the Metric of Aquatic Invertebrates for Volunteers (MAIV): (S4) Tolerance scores of the surrogates. The scores increase as the tolerance decrease; and (S5) Boundaries between ecological quality classes. Calculation of the Metric of Aquatic Invertebrates for Volunteers (MAIV): 1. Determine the presence of taxa included in Table S4. 2. Obtain the sum the respective tolerance score for each presence. 3. The sum of the total scores corresponds to the score of the sample. 4. Convert the score of the sample into quality classes, according to the boundaries expressed in Table S5. 5. To support decisions related with the boundary good-moderate, it is advisable to keep an interval of 5% of uncertainty around this boundary, from score 41 to score 49.

Table S4. Tolerance scores of the surrogates. The scores increase as the tolerance decreases.

Vernacular name Scientific name Tolerance score Fresh water worms Oligochaeta 2 Midge blood larvae Chironomidae 2 Flatworm Planaria 5 Leach Hirudinea 5 Freshwater snail Gastropoda 5 Freshwater mussel Bivalvia 5 Freshwater slater Isopoda 5 Dragonfly Anisoptera 5 Damselfly Zygoptera 5 Beetle Coleoptera 5 Black-Fly larvae Simuliidae 5 Fly larvae Diptera 5 Freshwater scud Amphipoda 6 Shrimps and crabs Crustacea 6 Mayfly Ephemeroptera 6 Caddisfly Trichoptera 6 Alderfly larvae Megaloptera 6 Stonefly Plecoptera 10

Table S5. Score intervals for each ecological quality classes.

Classes MAIV High >60 Good 46 to 60 Moderate 31 to 45 Fair 15 to 30 Bad <15