Using a belt transect to investigate the distribution and abundance of species with an abiotic variable up a sheltered rock shore
Investigating abundance of Gibbula umbilicalis with microhabitat
Investigating abundance of Gibbula umbilicalis with microhabitat
- Aim
- To investigate the effect of using different quadrat types on estimate of the size of a population
- To understand how to use a quadrat to estimate density and percentage cover
- To investigate whether periwinkles show a preference to different environments on a rocky shore
- Null Hypothesis
- There will be no statistically significant difference between the areas that periwinkles preferable inhabit on a rocky shore
- Location
- Jetty Beach, a sheltered rocky beach
- Method
- Lay a tape measure parallel to the coast at a distance of 5 metres
- Use a random number generator to select an area along the transect to place a 1mx1m quadrat
- Then within the area of the quadrat identify the periwinkles and in what type of microhabitat it is situated in out of rocks, pools, pool edges, crevices, seaweed and other
- Record how many periwinkles are at each microhabitat and repeat steps 3 and 4 for 4 more locations along the transect
- Carry out a chi squared test to see if there was a statistically significant difference between the locations
- Results
- Analysis
- For us to be certain of our result our total value much be above a critical value. This critical value is obtained by working out the degrees of freedom and the significance level. We want to be 95% certain that there is a statistically significant difference. This would mean we use the significance value 0.05. The critical value is 11.070 which is smaller than our Chi square value of 155.383. This means there is a statistically significant difference and that there is a preference for the periwinkles habitat, thus rejecting the null hypothesis
- Evaluation
- We could repeat this experiment or include the classes results to make an average for multiple experiments. This would mean that anomalies would be less impactful on the overall result. It would also make our results more reliable