An investigation to show the correlation between the number of different species found, and the B.M.W.P score of the environment.

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Matthew Stone        Page  of

Matthew Stone


Introduction

For an explanation on BMWP, refer to appendix 1.

For background information on Osmington Bay, refer to appendix 2

Plan

Hypothesis

“The BMWP score will increase with the number of species found.”

This is because the larger the number of species, the more BMWP score there will be for the sample. With correlation to the environment, species that have a higher affinity for oxygen have a higher BMWP score. Therefore, if there is only one species in a riffle (a highly aerated and fast flowing part of the river, meaning high amounts of oxygen dissolved and low amounts of organic pollution), the BMWP score of the area will be higher than that of a pool (stagnant, little aeration, and large amounts of organic pollution (eutrification of the organic pollution causes low oxygen content)) with many species:

Statistical Support

Because I am trying to show the relationship between to different pieces of data, I will use the Spearman’s Rank Co-efficient. Statistically, this will show whether the number of species found is significantly correlated to the BMWP score. I will therefore need to collect over 12 sets of data to make statistically analysing the data productive.

Variables

The variable that I will be looking to measure is the Number of species present.

Variables that I will be looking to control are

  • Kick sampling length of time – by using a stopwatch to time how long the kick sampling takes place; the size of the sample can be controlled. Equilibrium must be reached between sufficient number of species collected, and too large a sample to be analysed in 5 minutes.
  • Areas from which samples are obtained – I will use to different sites per area which show roughly the same environmental characteristics to have valid data to acquire a spearman's rank coefficient. Therefore I will collect data from various riffles, and various pools.

Pilot Study

Because I am using the Spearman’s Rank Co-efficient, I will need to collect at least 12-15 pairs of measurements in different parts of the river. I have to use different parts of the area, because if I only take a sample from one area, a variable which is present in only that section of the river would make my results void. If I use samples from different areas of river, I can identify variables which are out of my control via anomalous results. I will collect 2 samples per area of river (1 riffle, 1 pool) and record the number of species present. These measurements will be taken at the source of the River (Upwey), the middle of the river (Broadwey), and the mouth of the river (Weymouth). I will not take many variables into consideration at this point, because I only want a rough estimation of how many species are present in one area.

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I will use kick sampling for 1 minute as a method of collecting my data.

Kick sampling involves standing in front of a sweep net, and disturbing the sedimentary so that any species present are carried into the net. The nature of kick sampling means that I must stand in front of a net and kick the sedimentary downstream.

Once I have my sedimentary, I will empty the net into a white tray full of water. Then for 5 minutes I will count the number of species present.

Method

In the pilot study, it was found ...

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