Page 201 - Freshwater-Biology-and-Ecology-Handbook

3.4.1 Best time for surveys

A Riparian Sample is defined
Although many species are active throughout spring, summer and
autumn, between the first week in May and the last week in June is by Natural England as:
optimal. This is when adult beetle activity is often at its peak.
For each of four stations
Surveys should be carried out during dry weather when river • one hour hand searching
levels are normal or low. It is also crucial to check the long-range • an additional 20 minutes excavation
weather forecast before setting pitfall traps.
(on sand and shingle bars only)
At one station, usually the one with the
3.4.2 What is a standard largest area of open sand or shingle
• ten pitfall traps in place for a two-week period
riparian sample?

The combined results can be used to provide
There are a variety of techniques with no single optimum way a species list for quality assessment, but
to survey. Some techniques are rapid and do not require repeat the results should also be retained for the
visits whereas other methods collect more individuals but can be individual stations for two reasons:
resource intensive. One approach uses a series of techniques a. it allows for specific interest features on the
with the aim of collecting a large diversity of species in a relatively site to be identified (eg Atheta basicornis
short time period (Natural England, 2017); see also Webb et al. found under riparian tree bark at grid ref X)
(2022). (65)
b. pitfall trapping was excluded from some
earlier surveys; keeping separate records
On any given stretch of river, four sample stations are selected of the results (pitfall and hand searching)
in close proximity to each other (c.200 m). These are usually allows comparisons with the results of
identified beforehand and tend to each be located on a sand earlier surveys.
or shingle bank and its associated habitats. These are often
situated along a series of bends in the river.

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