"Investigating the distribution of streams invertebrates"

Essay by cenourinha28College, UndergraduateA-, November 2003

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1) We investigate the distribution of Benthic invertebrates at the Nant Iago stream, which is near Abergaveng in South Wales;

2) We measured a 150 m stretch of the stream, each group had a 10 m stretch meter long of stream;

3) A surber sample was used, the size of the holes in the net was 1 mm2, while the size of the quadrat was 0.1 m2 (this size prevents the invertebrates from passing through the holes, but small particles of fine sand could);

4) We placed the quadrats so it was flat in an area which was firstly slow flowing and then fast flowing (stony and sandy regions);

5) We the disturbed the area by turning the rocks and brushed then lightly into the net so that the species were washed in by the current;

6) Then we put the species that were inside of the net into a white tray and identified the species and counted them;

7) At each sample site we also measured:

a) Temperature by putting a thermometer in the water until it stabilised, then we recorded it;

b) Dissolved Oxygen by using a probe which we stirred, for about 30 seconds, in the water encouraging the water to move, then we recorded it;

c) pH by using a pH meter which was put in the water, then we recorded it;

d) Depth of water by using a metal measuring tape, then we recorded it;

e) Velocity by using a probe that we put in the water, then we recorded it;

f) Sediment size by estimating the size and by comparing it with a card given to us with many possible sizes, then we recorded it;

g) T.D.S.

by using a probe which we put into the water, then we recorded it;

h) The...