The Effect of Height on the Abundance of Rough Periwinkles on an Exposed Shore Essay

9989 WordsNov 22, 201440 Pages
The Effect of Height on the Abundance of Rough Periwinkles on an Exposed shore Aim of Investigation- To find out the effect of height on the abundance of rough periwinkles (Littorina Saxatilis) on an exposed shore. Independent variable - the height above chart datum chosen to count the abundance of rough periwinkles Dependent variable - the number of rough periwinkles per quadrat along a tape measure chosen by a random number Abstract I wanted to investigate why the abundance of organisms distributed at different sites have a pattern, and what factors affected this, so I set up an experiment where I would aim to find out how the height affected the abundance of rough periwinkles on an exposed shore. I decided to approach this problem by selecting two separate sites with different biotic and abiotic factors in this case it was two different heights above chart datum. I decided to use random stratified sampling to count the abundance of rough periwinkles via a quadrat. I then used the data I collected and conducted two statistical analysis on the results; the Mann-Whitney U test, a statistical analysis test for assessing whether two samples of data of independent observations have larger values than the other, and a box plot which is a convenient way of graphically portraying two sets of numerical data, and seeing if any values overlap. After conducting my analysis I came to the conclusion based on my results that there is a statistically significant difference in the number of rough periwinkles between 7m and 5m above chart datum. I realised that the higher the height above chart datum the greater the abundance of rough periwinkles, this may have been because of their respiratory kit works better at higher heights where more air is available due to low levels of immersion. The number of rough periwinkles may have also increased at higher heights above chart

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