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Investigating adaptation, competition and zonation of barnacles, Chthamalus stellatus (Poli) and Balanus balanoides (Linneas) on a semi-exposed southwestern seashore.

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Investigating adaptation, competition and zonation of barnacles, Chthamalus stellatus (Poli) and Balanus balanoides (Linneas) on a semi-exposed southwestern seashore. Victoria Privett, Plymouth High School for Girls. Introduction Invasions of ecosystems by exotic species are increasing, especially in aquatic environments. Barnacles populate the coastlines of countries around the world. Specifically in Britain, we have two main types, which along the southwestern coastline have become distinguished for their different zones. Within this competition for feeding and survival, there is not substantial vertical overlap. This investigation is viable when talking about the competition of species. One of the most famous ecological field studies is that by Joseph Connell on the rocky shores of Scotland. The distribution of two competing species of barnacles, Balanus balanoides and Chthamalus stellatus, has shown to depend on physiology (tolerance of desiccation) and predation as well as aggressive competition by Balanus. (image1) Biology behind my investigation As Chthamalus stellatus (Poli) has migrated to the British Isles, the competition between the native British barnacle, Balanus balanoides (Linneas) has become evididnt. There is clear zonation between the two species, with little overlay due to the diverse habitats at which the barnacles have become adapted. The main cause for this separation is due to the ability of the different species to survive under different conditions, to be able to function effectively, to feed and to reproduce successfully without hindrance from the environment around them. ...read more.


Method of the investigation. The investigation to test the hypothesis, took place on a semi-sheltered coastline in the south west of England. This site was chosen because there was the possibility of reproducing other transects over different locations to allow variations in data to produce a broader range as to which calculate the values. The area which was chosen to place the transect contains similar densities of Chthamalus stellatus and Balanus balanoides, suggesting that this rocky seashore would be ideal for quantifying the invasion of Chthamalus and recording the competition in invasion success. The percentage density of the two species from high tide level to mean low tide level was measured, along two transects that ran perpendicular to the sea. To this, the hypothesis can be applied and to distinguish a pattern of the distribution of the two species. By taking my quadrat readings at random, and ensuring that they are along the same transect; this would allow there to be an assumption that the test carried out would be a fair test. By doing so, the statistics recorded will not be manipulated and altered, by placing on a spot significant to that of no integration. By carrying out the experiment in this way, there will be want to strive to disprove the null hypothesis. ...read more.


The transect results taken, were averaged and so represent the area of my study. The hypothesis was to see if there was a complete segregation of the two species. To carry out this experiment and record results is not enough to prove or disprove the hypothesis. There must be some statistical conversion to the investigation and results to prove significant or to be concordant with the null hypothesis. Statistics-Chi2 Chi-squared can be used mainly for associations between two things. In the case of my investigation, is applied to find out the association between the two species of barnacles e.g. do you find Chthamalus stellatus where you find Balanus balanoides? The statistics proved that the investigation was very significant. For this investigation, the expected value of chi2 was 36.42, with a 0.05 value of probability. After collecting the expected and observed data and following the statistical formulae- X2=? (O-E) 2 E Where O represents Observed values and E represents the Expected values, the observed value was higher than the expected value; therefore, it is obvious that there is a 5% probability that the difference is down to chance alone. The overall value for the investigation carried out was 63.48; therefore, the null hypothesis is incorrect. Supported statistically the original hypothesis is and highly significant. Conclusion With reference to this investigation and it's statistically supportive results this is as a fair and conclusive report on the zonation of barnacles. ...read more.

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