... a lot of carnivorous freshwater invertebrates such as water beetles and water mites are also found in pools which may feed on and reduce the abundance of smaller freshwater invertebrates. I also think the higher the velocity of the stream, the higher the abundance of swimming mayfly found there. This is because swimming mayflies require quite a lot of oxygen due to their rigid, immobile gills, and the higher the velocity of the water the more oxygen will be present in the waters for them to use. Statistical Analysis Mann-Whitney U test Hypothesis: There is a greater abundance of freshwater invertebrates in riffles compared to pools of Embercombe and Nutscale Water in June 2004. Null Hypothesis: There is no difference in the abundance of freshwater invertebrates in pools and riffles of Embercombe and Nutscale Waters in June 2004. The table shows the abundance of freshwater invertebrates found in pools and riffles at the six sampled ...

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