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RHP |
South African
River Health Programme |
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TO KICK OR NOT TO KICKFor field sampling of aquatic invertebrates, did you know that sampling of stones in the current of a river can be carried out in two main ways? The first way, "stone washing", is to sample stone by stone, washing and hand-picking the animals from each stone off the stones into a net or bucket. The second way is to "kick sample", in which process the stones on the bottom of the river are vigorously moved about using booted feet. The collecting net is held in a position where the animals, dislodged from the stones and the sand which is often present between and below the stones, will be carried by the current into the net. The specialist animals, which cling tenaciously to the stones tend to be under-represented in kick sampling, whereas the specialists living in the sand and gravel below the stones tend to be under-represented in stone washing. The two sampling methods do not give identical collections from a single site on a river. The SASS method of Dr Mark Chutter (Afridev) is based on "kick sampling". |