Page 96 - Freshwater-Biology-and-Ecology-Handbook

CHAPTER 2 7.1 – 7.2 7.1 Manual search

The 1-minute manual search always
accompanies the main sample.

It is done to collect individual specimens of species
that are unlikely to be collected in the main sample – in
particular, surface-dwelling animals such as pond skaters
and water crickets which move away rapidly from any
disturbance, and for animals attached to rocks and other
firm surfaces – in particular, limpets, blackfly pupae and
certain caddis larvae and pupae. The search will not
always be fruitful but must always be undertaken.
The 1-minute search may be split into an initial search for
surface-dwellers before you enter the stream, as these
are very sensitive to disturbance of the water surface, and
a subsequent search for attached animals on large stones
and other objects from the riverbed.

7.2 3-minute kick

sampling from shallow

rivers

The aim of kick sampling is to collect as many
animals as possible while minimising the
removal of gravel and wood from the riverbed.

On stony or gravelly beds, kick the riverbed with the heel
of your boot, holding the net a few centimetres away
so that animals flow into the net but stones drop before
reaching the net. Sweep the surface of mud and amongst
vegetation. Wash detritus and vegetation in the net (do not
include washing time in the 3 minutes).

Figure 2.5
Kick sampling © Judy England

96 | Freshwater Biology and Ecology Handbook
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