Quantitative collection of benthic macroinvertebrates

1. Select a suitable sample reach and habitat (e.g., a riffle). Sample beginning at the downstream end of the reach, and proceed across and then upstream. Place the Surber sampler (30cm by 30cm, 0.475mm mesh) on a riverbed at around 0.5m depth. Remove large (fist-size) cobbles within the sampler into a bucket quickly.

2. Disturb the finer substrate remaining within the quadrat to a depth of 5 – 10 cm, allowing the dislodged materials to be washed into the net. Sieve gently within the net (if you sieve roughly, the animals will be damaged so be careful.)

3. Collect those attached on cobbles by brushing them off into the bucket and move them to the Surber sampler. Collect the remnants in the net in a ziplock bag by washing with some water.

4. Repeat the sampling. One sample will be for identification and the other will be preserved for long-term collection (archive samples).

5. Store samples in cooling boxes and bring them back to the lab.

6. Place pebbles onto a white tray by small amounts to sort all the macroinvertebrates visible with naked eyes.

7. Sort macroinvertebrates into 6-well plates by their morphological similarity and then identify them under the dissecting microscope to family level using the identification manual.

8. Store identified samples by family level using 5% formalin as evidences.

9. Store archive samples in 5% formalin after picking macroinvertebrates.

10. For stored samples, replace formalin with 70% ethanol after a few months.