Once all the animals have been counted, carefully replace them into the dyke.
Safety: Be sure to have a secure footing when doing anything near and around the dyke, to prevent falling in.
Before doing any activity near the dyke, cover any cuts and abrasions with micropore tape, as there are some water-carrying diseases that could enter these cuts and could become infected.
Wash hands thoroughly before eating and do not put your hands in your mouth.
Fair Test: The same size net and preferably the same net should be used, so that the same capacity of animals can be caught in each dip.
The same motion of sweeping with the net should be used. I.e. sweep across one metre, turn, sweep back one metre and remove the net. This ensures a fair test, because that way all dips have the same opportunity to catch the animals.
Sweep the net at the same depth in the water, as some species dwell in the mud on the floor of the dyke, while some live nearer the top and sweeping at different depths would give a different impression as to the diversity of the dyke. For similar reasons, you should choose whether you sweep in the middle or toward the edge of the dke and stick to your choice every time you sweep.
Measurments & Repeats: I plan to sweep near the bottom of the dyke, towards the middle of the dyke away from the reeds. I will sweep across one metre, turn, sweep back one metre and return the net. The dip will be carried out around Midday, when the sun is out, and I will have a depth in the wash tub equivalent to three volumes of the milk container.
Prediction: I predict that in the polluted dyke, there will be fewer different types of creatures in the polluted dyke than in the non-polluted dyke, however, those species that can survive in the polluted duke will flourish and be of a much greater abundance than those in the fresh dyke.
There will be fewer types of species in the polluted dyke than in the non-polluted dyke because in the polluted dyke, there will be a high level of Nitrates and Phosphates, which alone will kill some species that cannot tolerate such circumstances. The Nitrates and Phosphates cause lots of plants to grow on the floor of the dyke and algae to grow on the surface. The algae blocks out sunlight which kills some species of aquatic animals aswell as all the plants along the bottom of the dyke. The plants on the bottom play an important role in the delicate balance of the dyke's ecosystem, as many habitats and breeding sites, which will exterminate certain species. All of these circumstances make surviving in this polluted dyke very difficult, and this is why I think there will be a lower amount of different animals living in this dyke.
In the non-polluted dyke, there are many more species that have to live on a similar amount of food. They have to compete for food - but not just food. There is less space to make a habitat, more competition for a mate, and general living space, again has to be fought for. This means that every species has a limited amount that can be sustained at any time.
In coming to this deduction, I consulted many sources. I read many textbooks on the subject. I searched the internet for some information, although I found not many items of worth.The staff at the Carlton Marshes nature reserves were very attentive and helped us with any queries we had, and some of my teachers have provided much help.
Conclusion: The results I have collected clearly demonstrate the trends that I predicted would appear. The unpolluted dyke had a wider range of species but each of fewer number, and the polluted dyke had a slimmer range of species but these species were of a greater numeracy. This trend can be attributed to the incresed level of Phosphates and Nitrates that can be found in the polluted dyke. The effects of this are as catalogued in my prediction.
Many animals in these polluted ponds have or are forced to develop adaptations, which allow them to endure the difficulties in sustaining life. One superb example is the Bloodworm. As is demonstrated in the results, there were no Bloodworms in the unpolluted pond (which may have been an anomolous result, as I was expecting a few) but there were 10 in the polluted one. A Bloodworms body is packed with Haemoglobin, which is found in the human's red blood cells. This substance bonds with Oxygen to form OxyHaemoglobin, and this allows the Bloodworm to extract more than enough Oxygen from it's surroundings, even when there is very little, like in the polluted dyke. This allows it to thrive in the polluted dyke, as there is less competition for other life - sustaining necessities like food and habitat.
Evaluation: There were a few results which seemed slightly suspect in their reliability, which if given the opportunity to rectify, I surely would. I was expecting at least a couple of Bloodworms to be found in the unpolluted dyke, because their absence gives the impression that they cannot survive in clean conditions, which is not so. I also was not expecting there to be any Mayfly Nymphs to be found in the polluted dyke, as they are very sensitive to pollution, and usually only inhabit the cleanest water. Other than these anomolies, I was quite satisfied with the results I recovered, because they eminate the prediction I have made.
There were very strict time restrictions on the dip, and our time was intercepted bu the lunch-hour. This only allowed us time for two samples to be taken from each dyke, and if given more time in the future, I would like to reenact the experiment with more repeats, because I feel this would more strongly highlight the patterns displayed this time around. These time restraints also forced us to approximate the number of cyclops in the polluted dyke. Had there been a great deal more time, I would have liked to have more carefully counted them in order to receive an exact figure.
Following some inquiry from staff and internet searches, I have come to understand that the reason for the Mayfly Nymph's appearance in the polluted dyke was due to the time of year, and that had we undergone this experiment a few weeks later, there would have been none. This caused me to consider how the time of year affects the appearance of other species in both dykes. If the time was available to me, I would like to carry out the experiment once at the beginning of every other month and record how the number of different species and the number of these species changes throughout the year. I imagine that the polluted dyke would have an even lower number of different species in the summer months, because at this time, the algae would become almost like a sheet across the top of the water, and this would block out the sunlight, leading to the death of the plants along the bed of the dyke, and consequentially, the loss of much habitat and reproduction grounds. This would cause those species that could survive to thrive even more than the figure we have recovered today. I believe the adverse effect would occur in the clean dyke, in that there will be more different types of species residing, but a fewer number of them would be able to be sustained by the dyke.
