Page 204 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 4 3.4.4 – 3.4.6

Figure 4.18
Pitfall trapping and hand searching, River Dove (Photo: Nick Mott)

3.4.4 Pitfall trapping

(67)
Based on Sadler and Bell (2000), ten small plastic cups, and placed in each of the main habitat types detected (eg
c.10 cm diameter, are dug into the sediment so that the rim coarse shingle, bare sand, vegetated sand, etc). It is also
is flush with the surface. These are filled one-third full of a important to cover each pitfall with an elevated plastic
50:50 mixture of propylene glycol and water, with a small grid guard (20 mm mesh size). This will allow beetles to
amount of detergent added to break the surface tension. be caught, but will reduce the incidence of accidental by-
Propylene glycol assists in sample preservation and catch of small mammals, reptiles and amphibians.
reduces evaporation.
Pitfalls are left at each site for at least two weeks, and not
At each site, these pitfalls are placed sufficiently high up more than four weeks, before collection and storage in
the bank (but still in the riparian zone) to lessen the risk of 50% ethanol; for species that are collected for analysis
flooding and/or hidden away to avoid detection. In large via DNA meta-barcoding, the current advice is to transfer
and diverse areas, pitfalls can be set at least 2 m apart them to 90% ethanol as soon as possible.

204 | Freshwater Biology and Ecology Handbook
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