River Thame Investigation How does the distribution of mayfly larvae depend upon the rate of flow of the river
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Introduction
Transfer-Encoding: chunked Example 8 River Thame Investigation How does the distribution of mayfly larvae depend upon the rate of flow of the river Thame Planning ? I had help from two of the field centre staff who helped me choose the factors and showed me how the probe worked. Aim: To see if there is a relationship between the numbers of macro invertebrates, looking at mayfly larvae, and the speed of the stream. Prediction: There will be more mayfly larvae when the speed of the stream increases. Background: The field centre staff, Bob and Eileen, gave a talk to the class about the different types of organisms found in the stream. They mentioned the macro invertebrates and how many of them are adapted to hold onto the rocks in the stream to avoid being swept away. They then hunt for prey by crawling along the river bed or hang off the rocks and capture meals as they fly by. I also think that they will be less in the slower water as it will be easier for the predators of the macro invertebrates to find them when they are in the slow water. ...read more.
Middle
Temperature every 0.5m. +/- 0.001 (oC) +/- 0.01 From right bank. 1 0.0 0.012 16.73 straight 0.5 0.260 16.34 stream 1.0 0.400 16.69 as 1.5 0.533 15.72 enters 2.0 0.686 16.36 centre 2.5 0.782 16.22 3.0 0.821 16.51 3.5 0.565 16.07 4.0 0.466 15.78 4.5 0.068 16.40 2 0.0 0.075 17.65 meander 0.5 0.254 16.88 1.0 0.580 16.60 1.5 0.993 16.54 2.0 1.305 16.23 2.5 1.574 16.23 3.0 1.333 16.11 3 after 0.0 0.251 16.83 weir 0.5 0.342 16.50 1.0 0.558 16.47 1.5 0.501 16.60 2.0 0.595 16.71 2.5 0.647 16.38 3.0 0.567 16.73 3.5 0.281 16.96 4.0 0.214 16.87 4.5 0.135 16.84 4 Environmental systems and societies teacher support material ________________ Example 8 Averages calculated using an excel spreadsheet. Each set of three was added and then divided by three. For example: Speed (m/s) Average speed Temperature Average +/- 0.001 m/s +/- 0.001 (oC) +/- 0.01 Temperature (oC) +/- 0.01 0.000 0.012 16.98 16.73 0.022 16.87 0.013 16.34 All graphs made using excel spreadsheets CORRELATION BETWEEN STREAM TEMPERATURE AND SPEED Speed m/s ________________ 2 1.5 1 Speed (m/s) 0.5 0 15 16 17 18 temperature C Spearman Rank correlation shows a correlation of 0.49 All correlations made using an excel spreadsheet. ...read more.
Conclusion
The temperature data took a long time to collect and yet the water temperature does not vary much from sample areas or sites. The probe to collect speed was very useful and should not have many errors as it averaged the speed over 10 seconds. I could have made an error in the placement of the flow meter ? I tried to keep it 1cm below the surface ? but I did not measure this and also the water was shallow in places making the blades get stuck. The time of year is a big factor as stream flow varies due to the weather conditions ? rainfall. The life cycle of the mayfly will also impact larvae numbers. The improvements would be to concentrate on collecting data that answers the prediction posed. Also to redo the whole investigation at different times of the year and in different weather conditions. The other data I collected could have also been used to see if other factors impact the location of mayfly larvae in a stream. I could have also looked at other macro invertebrates ? maybe ones that like slow moving water better. 1. G. Williams. Techniques and Fieldwork in Ecology. Collins Ed. 1994 8 Environmental systems and societies teacher support material ...read more.
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