The Effect of Pollution on the Distribution of Organisms Along the River Roding System
Pots and lids
Freshwater Invertebrate Key
Scrap Paper (note pad)
Tape to cover cuts
I investigated how the quality, amount of dissolved oxygen, nitrates,
phosphates and the temperature of the water in the River Roding System
affected the distribution of organisms in the river.
I chose six suitable sites along the river Roding System: Furze
Ground, Pyrles Brook, Debdon Brook Downstream, River Roding Upstream,
River Roding Middle Stream, and River Roding Downstream. Each site was
investigated in groups.
At each site we firstly sampled the biotics. We looked for the
indicator species (the invertebrates that are affected by pollution).
We obtained these samples by using the method of kick sampling.
A tray was filled with clear water from the river. One member of the
group stood in the river holding a net with his feet facing in the
direction of the flow as shown in the diagram above. That person then
shuffled his feet for 30 seconds catching the disturbed material in
the net. The material in the net was then placed in the tray of water.
For the next 10 minutes the invertebrates were identified from the
sample using a key. The numbers and types of invertebrates were
recorded. This was repeated once more in a different part of the site.
Then we tested for the abiotic factors. We did this at the site and so
had taken our equipment to the site. Firstly nitrates were tested for.
A member of the group removed the nitrate stick from the container and
dipped the end with the two pads in the river for 1 second. We waited
1 minute. The colour on the pad was compared with the colour chart to
see the nitrate level. The nitrate level was recorded. Then a
phosphate test was carried out. Firstly 5ml of the water from the
river was placed in a container. There were two reagents. 5 drops of
reagent 1 and 1 micro spoon of reagent 2 was added to the water. The
lid was replaced and the container was shaken. We waited 2 minutes and
took the lid off. The colour of the mixture was compared with the
colour chart and the phosphate content was recorded. Then the oxygen
test was carried out. The meter was set for air and the probe was
placed in the air. His was set as 100%. The probe was then placed in
the river and the reading went down or up comparing its oxygen content
with the oxygen in the air. Finally the temperature of the water was
measured. This was done using a thermometer.
At each sight we also noted down descriptions of the site e.g. the
surrounding land use, the cleanliness of the water, the depth and
width of the river. This was done so that...