|
It is important to collect at least 100 water bugs and preferably
150-200 bugs to get a reliable stream pollution index.
In slow moving water and pools, sweep the net across the
surface to collect striders and beetles. Drag the net beneath
the surface and through water plants to collect nymphs and
water scorpions. Snails and worms live among the rocks, litter
and sediment.
In fast flowing water with a rocky river bed, hold the net
on the floor of the river-bed so the mouth is facing upstream.
With the net in position, thoroughly kick and rub stones in
front of the net to dislodge the water bugs.
Practice is needed to scoop up water bugs from the stream
bed without collecting a lot of mud or rubbish. In muddy streams,
it is a good idea to shake the net thoroughly in the water
so that any mud is washed through it. As you finish sampling
each part, empty the net into a bucket, half full of stream
water.
|
