Methods
Light intensity – Used a light intensity detector,
Place it in the water and read the temperature for different sites in the pond.
Oxygen concentration – Used an oxygen concentration detector, bottle of pond water. First off all we got pond water in the bottle and shacked it for 1minute. Then we turned the meter on and opened the lid of the bottle. Place the meter in the bottle until it reached to 100. After that we put the meter in the pond and read readings at different sites in the pond.
Water temperature – water temperature meter
We placed the meter in the water and read the reading at different sites.
Substrate depth – Used a depth ruler.
First off all we took the depth of the river without the substrate at the bottom. After that we took the depth with the substrate. To achieve the substrate depth = normal depth – substrate.
We took 3 readings.
Acidity – Used universal indicator paper.
Place the small amount of paper in the water and saw what colour it turned into. Took different readings from different sites.
Invertebrate diversity – Used a sieve/net, tray for the insects and an identification key, magnifying glass, small pot and a pipette/spoon.
First off all we put the net in the water and took a figure of 8 for 1 minute. Then we put some pond water in the container and then placed the species in the container. After that we identified them using the species key. The species we identified we placed them in a separate bowl with pond water.
To ensure we made a fair test we did many things such as:
- Taking 3 readings for different variables at different sites from each pond.
- For the species diversity we did figure of 8 in a minute at different sites for each pond.
- Used equipment accurately.
- For the species diversity we used a key to give a more accurate variety.
- We used different sites in each pond for example open water, grassland, mud, and plant life.
- We done same number of times for the different variables at each pond.
- To make the diversity of species fair test we did it once from each site but then there were 5 groups (including mine) which took their results from the same site. After we took an average to make it more reliable.
Results and analysis
Summary of Aboitic results
Meadow pond - Simpson’s diversity index
Simpson’s Diversity index= N (N-1)
-------- = 2239 times 2238= 5010882
n (n-1) ----------- = 2.24
2241114
Simpson’s diversity index - 980 times 979 = 959420
----------= 2.00
479652
Conclusion
Both habitat diversity and pond type have affected species diversity. As I predicted that meadow pond will have the higher species diversity in which I was correct.
I predicted that if there is more sunlight reaching the plant there would be a large number of plants growing in which there will be more herbivores which feed on the autotrophs resulting in a greater number of diversity.
Looking at both results there was a big difference in specie abundance but a small difference in species diversity of only 24. Also looking from the meadow pond results the species assemblage patterns were influenced by the environment. The species diversity was positively correlated with the abiotic factors such as high levels of light meaning more plants to feed on, great amounts of oxygen and warmer water.
The things could affected our result was the seasonal differences in the population of aquatic species, movement of invertebrates into or out of the study area, small changes in pond characteristics or other things I did not measure.
Therefore the higher value of Simpson’s diversity, the higher the diversity of the community and the greater the intrinsic value.
Pyramid of number – Meadow pond
Looking at the graph for the pyramid of number of the meadow pond it shows is going in a pyramid shape. The hypothesis was correct because I predicted the meadow pond will have more herbivores compared to detrivores and carnivores because the meadow pond has more plants to feed from.
however it can also be expected for the m.p to have more carnivores as there are more herbivores to feed on this may not be evident due to human error. This maybe because I did not get readings from the middle of the pond as sampling was only done on the edge so there wasn’t an accurate data for the carnivores.
However there is a significant amount of decomposers which was not expected due to the conditions of the pond.
Pyramid of Biomass –meadow pond
From looking at pyramid it shows the hypotheses is wrong as there are more 2nd carnivores compared to 1st carnivores and herbivores. This is maybe because there’s more food from the carnivores and herbivores.
Also as you can see there are more decomposers due to the fact of bad weather and seasonal changes so they’re dying out.
Looking at these herbivores there is less then the 2nd carnivores. This maybe a human error as the herbivores are so small
Pyramid of number: woodland pond
Looking at this pyramid it shows the hypothesis was incorrect because there is less decomposers then herbivores which should be the other way round. This is because a lot of dead leaves from the surrounding trees fall into the pond. Also there should be less herbivore because there’s shading by the trees which gives less light for the producers so less food for herbivores.
Pyramid of biomass- woodland pond
Looking at this pyramid it shows the hypothesis is wrong. It can be seen that there are less decomposers, 1st carnivores and herbivores But more 2nd carnivores. This is a human error as larger carnivores are more seen than the smaller carnivores and herbivores. Another is, plants dying in the winter so life cycle of herbivores changes.
Conclusion of abiotic factors
Water temperature
From the summary table you can clearly see that the temperature is higher in the meadow pond with a reading of 10.66 then in the woodland pond with a reading of 9.68. This is because more light is reaching the water due to no shading of trees.
Light intensity
From the summary table it shows there’s more light reaching the meadow pond with a reading of 3186 then woodland pond with a reading of 666. This is because the pond receives more direct sunlight.
Oxygen concentration
From the table it shows there’s more oxygen in the meadow pond with a reading of 50.67 then the woodland pond with a reading of 36.25. In meadow pond there isn’t shading of trees so more photosynthesis is occurring so more oxygen produced.
pH
Our hypothesis on the pH was correct. The pH in the meadow was more acidic than the woodland. However it was not meant to be because there are decomposers in the wood land pond as they work best in acidic conditions. This is maybe because we measured the pH at the edge of both ponds. The centre of the woodland pond maybe more acidic.
Substrate data
From the data it can be seen then the woodland pond has a higher level of substrate with a reading of 13.7 than meadow pond with a reading of 4.6. This is a result from deciduous trees which loose their leaves and then fall into pond.
Evaluation
Limitations
- Some species are not accurately counted, for example water flea which are very small which disrupts biomass. Also some species may escape from the net as they are very tiny. Also decomposers such as micro organisms may escape from the net which disrupts the biomass.
- Less visibility in mud areas so not reliable in the number of species found.
- Different people have different techniques as so their sampling is not the same.
- Substrate depth not accurate due to the metre rule not placed correctly on the pond bed-obstacles and also no access to middle pond
- Temperature – might vary at different times as we only took the readings on 1 day. As the result might vary on another day.
- Ph inaccuracy – only did it on the edge of the pond