Species Diversity on a Rocky Beach Essay Sample

Species Diversity on a Rocky Beach Pages
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We were asked to investigate how species diversity on a rocky beach alters, depending on what tidal area we were in. We went to Brady Cove, near Swansea, on the Gower, in order to do this. We decided that the best way to investigate diversity alteration was by splitting the beach area in to 6 pieces. Like so:

There were two people on each section of the beach, each pair obtained the same amount of results using line transects (three in each section).


As mentioned in the introduction we will be splitting the beach up into 6 sections. This will make it easier to find differences in species diversity. The sections are: high tide left, high tide right, mid tide left, low right and low tide left (as depicted by the diagram). We will do two line transects in each section of the beach, then convert the results into a species diversity index, we will then be able to compare the results in order to find which section of the beach has the highest species diversity.

Then I will investigate the type of conditions each section is exposed to and how this will affect which species lives in each section of the beach. For example, whether the section is shielded from rain, reached by the tide, or if it is exposed to sunlight for long periods of time. This could affect the different sorts of species that live in certain sections of the beach. We will record 200 separate results in each section of the beach (two line transects each with 100 results.). To generate reliable and accurate evidence, we will be cautious to record the right results for each mark along the transects. The transects will be carried out on the same day, and hopefully under the same weather conditions

The line transects will be taken from random points in each sector. Then the variety of creature will be recorded at every 10 centimetres along the line. The species will be recorded using abbreviations of their name (e.g. for barnacle we would use BA) to make it more convenient to record the results.


I am now going to make a prediction on what results will be obtained in each section of the beach and give reasons why I feel this. I have split my prediction into 3 parts for the 3 tidal areas of the beach.

High tide

This section is surrounded by dry rocks and is not often reached by the tide. I believe that because of the constant conditions the species diversity will be low, because very few species will be able to survive in this area. The lack of moisture in the summer will make it hard for many types of creature to survive, and if they do they will be killed off by the cold winters that Britain experiences.

Mid tide

This section of the beach is very exposed and has rocks around its edges. The tide reaches this section, and so it will be fairly damp. However, it is an open area and may be the hunting areas for many birds, or other local wild life. The edges of the section could be home to many small creatures, such as barnacles, this would be because of its rocky areas as these are ideal places for this sort of creature to populate. I believe that with taken into account there will be a reasonablely large species diversity.

Low tide

This section of the beach is covered by the sea most often, it has patches of seaweed all over it and also many rock-pools. There are also patches of rock over this section of the beach. This could be home to various types of seaweed, and living amongst that seaweed there could be organisms. I believe that this will cause there to be high species diversity on this section of the beach.

These predictions were made in regard to a previous experiment that we did on the school playing fields, in which we used line transects to find species diversity. After looking over the results of this investigation again I have decided that even minor changes in the a habitat (the length of the grass in this case) can have a large effect on the species diversity. The results of our experiment are below:

Area one

Area two

Grass – 73

Grass – 55

Dandelion – 15

Daisy – 15

Daisy – 12

Speedwell – 17

Dandelion – 13

The results are shown as the number of points out of 100 which were covered by the certain species. The results show that there was a greater species diversity in area two than in area one. Area two had longer grass and this obviously made a difference in the results.


These are the results (in species diversity) that we obtained for each area of the beach:

Low tide left 1 – 0.53 Mid tide left 1 – 0.36 High tide left 1 – 0.29

Low tide left 2 – 0.36 Mid tide left 2 – 0.31 High tide left 2 – 0.34

Low tide left 3 – 0.26 Mid tide left 3 – 0.51 High tide left 3 – 0.31

Low tide right 1 – 0.61 Mid tide right 1- 0.28 High tide right 1 – 0.53

Low tide right 2 – 0.48 Mid tide right 2 – 0.29 High tide right 2 – 0.40

Low tide right 3 – 0.36 Mid tide right 3 – 0.25 High tide right 3 – 0.47


After carrying out the investigation in the planned way, I have found; that the climate and conditions organisms live in does affect species diversity, areas with the most constant conditions have the greatest diversity (in the investigation this was the front and the back of the beach). The mid section of the beach, which had the lowest diversity, was very open and had no shelter from weather or predators because of this. I believe this is the primary reason why it had the least species diversity, animals had nowhere to hide from predators and no shelter from various climates. The low tide area on the other hand had a high species diversity, and I believe that this was due to the amount of seaweed that was washed up on the shore of the beach.

The results from the low tide area of the beach show that the species stay at a constant diversity, this shows that they are living off each other in order to survive. The fact that there is no change in the diversity shows that the types of species stay the same right across the front of the beach. This has proved my prediction wrong. There is not a great diversity of species, although there may be the most organisms living there they generally stay the same, this could have been due to Darwin’s theory of natural selection, where only the strongest and most well adapted organisms have survived.

The results in the mid tide area of the beach, could tell us that the right side of the beach is easier to live in than the left side. From the results, we can see that the left side appears to have a larger variety of organisms living there so conditions must be easier to survive in. To a certain extent these results back-up my original prediction. There is an higher species diversity, but only in one sector of the mid tide sectors. However, the other side of that sector has a lower species diversity, so it challenges the original prediction. In total though, I believe that this sector is not as I predicted.

The high tide sector of the beach has two very different sets of results. The right hand side of the sector seems to have an unexpectedly high species diversity, this is not as I predicted. I have looked over the different sectors of the shore and have come to the conclusion that the odd set of results was due to errors carrying out the investigation. In consideration to this I have decided that there was still evidence to prove my prediction wrong although some of it was incorrect. There appeared to be a reasonable species diversity in this area, although I was expecting to see it much lower.


Looking back at the whole procedure I believe that we carried out the investigation in the way we planned to, though it was not as good as I could have been. We came up with some extremely odd results. This could have been due to errors in the obtaining of the results, which can only be blamed on the original plan. The evidence that we obtained was reasonably reliable although the high tide area of the beach did give us some very odd results. This was probably due to human error in the obtaining of results.

The accuracy of the equipment we used was suitable (although it could have been better) and we managed to collect a reasonable amount of results, and also a suitable accuracy within those results.

I believe that a better plan would have resulted in more accurate results being taken, as we would have spent more time trying to find out how to overcome the problems of inaccuracy. I also believe that given more time on the beach, we could have split the beach into even more sectors and therefore taken more results. This would have given us a better idea of how the species diversity was affected in the different areas of the beach (although on the day we would not have had time to obtain these results).

The results we came up with are not really of a high enough quality to provide a good conclusion into the species diversity of a rocky shore. Although with the results we obtained I would say that the diversity in each sector is dependant upon the different conditions that each sector is subject to.

The harsher the conditions are, the harder it will be for the creature to live in, and this will result in a lower species diversity, for example the low tide sector is subject to constant battering from the sea which is a problem for species to overcome. In the past we might have found that species living in the mid tide sector may have lived in the low tide sector, but because of natural selection, they have moved up the beach and found a habitat that they are more suited to. The conditions seem to get harder to survive in as you move down the beach, especially on the left-hand side. I believe that the left hand side may be the side of the beach which is subject to the wind more than the right hand side. To make a conclusion I would say that the species diversity is lower in areas where it is harder to live, and higher where creature find it easy to live.

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