Investigation of the distribution and abundance off reshwater invertebrates in the Tillingbourne River at Abinger Hammeron Thursday, 17th of October 2002
Investigation of the distribution and abundance of freshwater invertebrates in the Tillingbourne River at Abinger Hammer on Thursday, 17th of October 2002
Introduction
My research is about the distribution and abundance of freshwater invertebrates in the Tillingbourne River at Abinger Hammer at Surrey, England. Invertebrates are living organisms without backbones therefore there must be a number of factors, which affect the way they live and reproduce. The distribution of an invertebrate is partially affected by its environment. I chose to observe which species of invertebrates lived in the middle and at the edge of the riverbed- the river being their habitat.
I feel that the three most important abiotic factors that contribute to the distribution and abundance of such invertebrates are the flow rate i.e. the velocity of the water, the temperature and the oxygen levels. As well as measuring these three things I did a kick sampling to see which different species I would be able to find in the invertebrates' habitat- the river.
There were also various safety measures we took such as wearing gloves and waterproof clothing to protect us from any harmful diseases. We were instructed to handle all equipment gently and accurately to ensure that the results are as accurate as possible. The weather that day was quite sunny that day, which was useful for us because the sunlight enabled us to see well. We took our edge sample from the left side of the river as well as our flow rate, dissolved oxygen and temperature levels. Our middle sample was taken from, you guessed it....the middle.
Throughout the rest of this research you will find the results of my observations on the flow rate, oxygen levels and the different species of freshwater invertebrates that I found.
Predictions:
. The water velocity is going to be greater at the middle of the river.
2. The water temperature will be greater at the edge of the river.
3. Dissolved Oxygen (O() levels are going to be greater at the middle of the river because the warm water in the middle of the river will not hold onto as much oxygen as the supposedly cold water at the edge of the river.
4. More invertebrates will live at the edge of the river because they have the adaptations to live there. *
* There is less competition to live at the middle of the river because there are fewer invertebrates there and the invertebrates that live there adapt by having suckers, which are used to suck onto stones. There are more stones in the middle of the river than at the edge and they are often carried downstream depending on the river's water velocity. More sand and mud is found at the edge because little bits of rock break of the stones as they are carried downstream and they float in the water for a while then settle at the edge of the river.
Methods
Equipment we used during our research:
* Gloves- to ensure protection against harmful diseases such as Weil's disease
* Flow metres- 1 used per group (each group had approximately 4 or 5 people). They measure the velocity of the water.
* Oxygen metre- to measure the levels of oxygen in the middle and edge of the river
* Water & Disinfectant- (same purpose as gloves)
* Pond net- to catch invertebrates with
* A clipboard- to press on when writing
* Paper- to write down and record results
* Pencil- to write with. Do not use pen because the ink will 'run' if it gets wet with river water.
* 2 pots with lids- to keep the caught invertebrates in. 1 for the middle invertebrates and one for those caught at the edge of the river.
* 2 spoons- to pick up larger invertebrates with
* 2 pipettes- to pick up smaller invertebrates with
* 1 white tray- to put invertebrates caught from river with pond net in. Make sure water is in the tray so the invertebrates don't die.
* Wellington Boots- to ensure that feet do not get wet
* Waterproof clothing- to ensure our bodies don't get wet
There were four things we did at the middle and edge of the riverbed in the Tillingbourne River at Abinger Hammer. They are:
* A 30 second kick sampling at both the middle and edge of the river to catch the invertebrates in a pond net.
* Measuring the flow rate- the velocity of the water- of the water in the river at the edge and middle with a hydro prop flow meter
* Measuring the Temperature of the river at both the middle and edge in (C using a thermometer
* Measuring the Dissolved Oxygen (O() levels in parts per million (ppm) with an Oxygen Metre
Two people performed the kick sampling both times, at the middle and edge of the river. At the edge, one person held the pond net and kicked and the other person just kicked disturbing the invertebrates' habitat. The invertebrates were then caught in the pond net while they were moving about. At the middle, one person held the pond net and kicked and the other person just kicked. The invertebrates were disturbed and we even got a stone with quite a few invertebrates sucking onto it. Both kick samples were timed to be exactly 30 seconds each.
When we were measuring the flow rate we used a hydro prop flow metre. To read the flow rate in a hydro prop flow metre one must carefully place the equipment in the water then look at the meter watching the propeller to see how long it took for the propeller to go from one end to the other and then a conversion chart to calculate the measurement from seconds to metre per second.
When we measured the temperature we kept a thermometer in the water then took it out and read and recorded the temperature in (C.
We measured the Dissolved Oxygen (O() levels in parts per million (ppm) with an Oxygen Metre by taking the probe cover off the Oxygen Metre carefully and gently placing the Oxygen Metre in the water ensuring that everything is working in the right order and all the parts are where they should be.
Analysis
Abiotic factors
There are a number of Abiotic factors that affect the distribution and abundance of freshwater invertebrates in a small river. Listed below are many of the main and most important ones:
* Air temperature
* Water velocity
* Water depth
* Water temperature
* Dissolved gases
* Light density
* Daylength
Common Name
Middle Invertebrates
Edge Invertebrates
Freshwater Shrimp
2
70
Swimming Mayfly Nymph
4
0
Alderfly Larvae
2
0
Caseless Caddisfly Larva
0
Beetle Larva
5
0
Water Boatmen
0
Fly Larva
8
0
Types Of Invertebrates: 23
Total: 32
Total: 71
As you can see from the table to the left, we found over double the amount of invertebrates at the edge of the river rather than in the middle. This may be for a number of reasons, the most prominent being that more invertebrates are adapted and suited to live in the muddy, silt filled edges of the riverbed rather than the stony, high water velocity areas of the middle. We found a total of 7 species; this may be because of misidentification or the contamination of the area we took our results from.
There were quite a few freshwater shrimp. This was the most frequent invertebrate found by all 7 groups; there was a total of 402 freshwater shrimp found in the middle and edge of the river in total. We may not have been able to catch all of them because they are extremely fast swimmers and there were 152 more shrimps found at the edge than at the middle.
I would have expected more freshwater shrimp to be found at the middle of the river, the middle of the riverbed may have been disturbed when people walked through the riverbed forcing the invertebrates to swim to the edge of the river. Others such as the Caseless Caddisfly larvae have hooks and they weave webs onto stones in the middle enabling them to reside there are move when they feel necessary.
No burrowing mayfly nymphs were found; this may be because of their special adaptation in their tails that allows them to burrow deep in the ground ...
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I would have expected more freshwater shrimp to be found at the middle of the river, the middle of the riverbed may have been disturbed when people walked through the riverbed forcing the invertebrates to swim to the edge of the river. Others such as the Caseless Caddisfly larvae have hooks and they weave webs onto stones in the middle enabling them to reside there are move when they feel necessary.
No burrowing mayfly nymphs were found; this may be because of their special adaptation in their tails that allows them to burrow deep in the ground and there might not have been enough of a disturbance to cause the nymph to come out and hopefully be caught.
The table below indicates the flow rate in the middle and edge of the river as my group recorded it. As you can see the middle of the river has over 6 times the velocity of the edge of the river. The flow rate is a very important abiotic factor that contributes to the abundance and distribution of the freshwater invertebrates in a river. The reason for this is because the invertebrates have to be adapted and suited to the velocity of the water because if it is too strong then it will pull the invertebrates away and send them downstream with the water. The stones that are found in the middle of the water allow them to hold onto it. Many invertebrates that can be found in the middle of the river are adapted with suckers for holding onto the stones such as leeches or can burrow into the bottom of the riverbed such as the burrowing mayfly nymph.
Section of River -->
Middle of the river
Edge of the river
Flow Rate (m/s) -->
0.85
0.13
The table below shows the results of all 7 groups that also performed this research. As you can see, the results of my group differ highly from the others. As I did not perform this measurement, I cannot pinpoint exactly what went wrong. Group 5 also got results, which were different. However, theirs did not differ as much as ours did. The average result is incorrect because our result is incorrect.
If the results of my group and of Group 5's were excluded from the average, an average of 0.42 would be present. However, this is larger than the average including our groups. The average including our groups were smaller because there is a larger number to divide the total of the results. There is a big mathematical miscalculation present because of the anomalous results of two groups.
Our results for the flow rate in m/s at the edge of the river were quite similar to many other groups. But once again, Group 5 got a higher result for the edge as they did for the middle. This alters the mean, giving us a not so accurate result.
Group-->
2
3
4
5
6
7
Mean
Section of River
M
E
M
E
M
E
M
E
M
E
M
E
M
E
M
E
Flow Rate (m/s)
0.33
0.28
0.28
0.17
0.85
0.13
0.18
0.10
0.50
0.39
0.26
0.15
0.23
0.15
0.38
0.20
Section of River -->
Middle of the river
Edge of the river
Dissolved Oxygen (ppm) -->
1.0
0.8
This table shows my group's recordings of the oxygen levels.
The table below shows the whole class's results as well as the average:
Group-->
2
3
4
5
6
7
Mean
M
E
M
E
M
E
M
E
M
E
M
E
M
E
M
E
Dissolved Oxygen Levels (ppm)
0.8
0.8
1
0.8
1.0
0.8
0.8
0.6
1
1
1
1
1
1
0.9
0.9
All of the measurements of the Dissolved Oxygen levels are similar. They differ by very small numbers; this may be because the levels of oxygen were recorded at different sections of the river. But the average of the oxygen levels are exactly the same for both the middle and the edge of the river. Groups 5,6, and 7 got the exact same results for the middle and edge of the river alike. However, it is most unlikely that the three groups were working very near each other. The reason there may be a slight difference in the dissolved oxygen levels is because of the time each group might have had the oxygen metre in the water and how they handled it. It is very important for the outcome of one's results to ensure that fair testing is carried out on both the middle and edge of the river.
Group-->
2
3
4
5
6
7
Mean
M
E
M
E
M
E
M
E
M
E
M
E
M
E
M
E
Temperature (ºC)
0.5
1
0.5
1
0.5
0.5
0.5
1
0
0
0.5
0.5
0.5
0
0.4
0.6
From the table above we can see that there is a slight difference in temperature but 0.2ºC is not very significant because an organism would not find that much of a difference in temperature if it moved from the middle of the river to its edge or vice versa. My group, of five people, recorded a temperature of 10.5ºC for both the middle and edge of the river. Our results were similar to five other groups for the middle and one other group for the edge. The reason for this is that the temperature may not have been held as long in each section of the river equally as the other or that the reading on the temperature may have been misinterpreted.
Section of River-->
Middle of the river
Edge of the river
Temperature (ºC)
0.5
0.5
Analysing the results of the predictions previously made
I would now like to state which of the predictions listed above was correct and which were incorrect. Before I continue I would like to add that some of the results may be incorrect, not because they were measured incorrectly or because the methods weren't followed correctly but because people may have expected things like the water velocity should be greater at the middle so they will record a higher velocity rather than putting their actual results in fear that their results may be different from someone else's.
. The water velocity is going to be greater at the middle of the river.
This prediction was correct. The water velocity i.e. the flow rate of the water was at the middle of the water was almost double that of the edge. The average of the results of all of the groups (a total of seven groups with approximately four or five people in a group) for the flow rate in metres per second at the edge of the river is a mean of 0.375 m/s and for the middle it was 0.196 m/s.
The reason the flow rate is greater at the middle of the river is because there is surface friction with the wind in the middle. There is the slowest flow closest to the bed because there is friction with the channel bed. The turbulence increases with the velocity of the waves. The flow rate is also less at the edge of the river because there is vegetation, which obstructs the path of flowing water.
2. The water temperature is going to be greater at the edge of the river.
This prediction proved to be false. The average of all the results of the seven groups show that even though there was an increase of 0.2(C at the edge of the river as opposed to the middle, this increase is very insignificant. The middle of the river was 10.4(C and at the edge it was 10.6(C.
The reason the water temperature was not greater at the edge of the river is because the water is constantly moving and the circulation of water makes the temperature the same everywhere.
3. Dissolved Oxygen (O() levels are going to be greater at the middle of the river because the warm water in the middle of the river will not hold onto as much oxygen as the supposedly cold water at the edge of the river.
This prediction also proved to be false. The dissolved oxygen levels were equal at the middle of the river and at the edge. They were both exact even though many groups got slightly different measurements in parts per metre (ppm); the individual group results, however, did not differ greatly because four out of seven of the groups got the exact same measurements for the edge and middle of the river and the other three's results only differed by 0.2ppm for the difference between the edge and middle of the river, each group getting a higher dissolved oxygen level for the middle.
The Dissolved Oxygen (O() levels are dependant on the temperature and flow rate of a river. If the water is hotter then it will hold onto less oxygen. Usually, the flow rate are also important in determining the oxygen levels but it wasn't this time because the water was fully saturated with oxygen.
Oxygen is a product of photosynthesis, a process that takes place in plants. As there is much vegetation in the river, more at the edge, more oxygen is produced. This is another reason the water is fully saturated with oxygen.
4. More invertebrates will live at the edge of the river because they have the adaptations to live there.
This prediction proved to be true because there was a result of a total of ninety-six more invertebrates for all seven groups. However, there may be a questioning in this result because two of the groups found that they had more invertebrates in the middle of the river.
The reason for this is because more invertebrates are adapted to living at the edge of the river than at the middle because of the high flow rate of water in the middle. Animals such as freshwater shrimp and burrowing mayfly nymphs are well adapted to live in the middle because they are good swimmers and burrowers (they can burrow deep into the ground). Animals that are adapted to living at the edge of the river are Springtails, they mainly feed on vegetation and therefore the edge of the river is more ideal for them rather than the middle. A problem with this result is that the middle section of the river may have been disturbed when someone may have walked through it forcing the invertebrates to flee to the edges, temporarily populating that area further.
Detailed description of six different freshwater invertebrates
I am now going to describe, in detail, five different species with their different adaptations that enable them to survive in the part of the river they live in. Each of the following inhabitants belongs to the population of other invertebrates like themselves. They live an ecosystem- the living organisms and the area they inhabitat as a whole.
Water boatmen
Water boatmen are insects that can be found in small rivers and streams. They prefer to live in rivers/ streams with a low water velocity because they are not well adapted enough to survive high currents; they are usually found on the surface of the river however, as they are good swimmers and land and river residing insects they can be found at either the edge of middle of the river. The results show that one was found at the middle and two at the edge, our group found one at the middle of the river, it may have been at the edge and moved or may have been swimming in search for food. They can live on land or in water making them amphibious. These aquatic bugs have paddle-like adaptations on their hind legs -which have stiff hairs that help them push against the water- that help them to swim quicker in a river. The one my group found in the Tillingbourne River was an exceptionally swift swimmer and was able to survive out of water when it jumped out of our tray before being caught. Their hind legs can become flattened allowing them to swim on their back. Water boatmen have elongate, oval bodies. They are dark coloured, often with lines on the front wings. The front legs are short and scoop-like; the middle and hind legs are elongate and oar-like and their beak is short and broad. Their wings give them the ability to fly out of the water if, for example, they suspect a predator is coming. They spend most of their time in the water coming up to the surface every so often causing them to collect bubbles of air, which the bug will carry, between the rows of hair on its abdomen. Their main sources of food are algae and other minute organisms. More predaceous water boatmen feed on small insect larvae and other small aquatic animals.
Springtails
These insects are very small in size and unlike water boatmen they do not have wings. It is very difficult not to recognise their distinctive heads and humpback figure. They have a fork-like feature on the lower part of their abdomens, which acts like a spring flipping them in the air. This action makes them look like water fleas thus the reason they are called Springtails. Most species are land animals, however, a certain species of this harmless animal can be found in steady flowing streams or rivers. This is the type two of the groups found. However, one of the groups found an unusual amount of springtails, this may be because of misidentification or the adjustment of results. Springtails are so small that larger animals that prey on them may spend a considerable amount of time simply searching for them. They can be found in the middle; however, they prefer to live in the more calm edge of the river or stream they choose to inhabit.
Caddisfly Larvae
Caddisfly larvae have 6 legs near their head and small tail hooks. These exquisite and worm-like creatures have a number of different species, as do many other organisms. Two of the main aquatic species are the Cased Caddisfly Larvae and the Caseless Caddisfly Larvae. The Cased Caddisfly Larvae makes it case from an assortment of indigenous materials such as twigs, mud and small stones; they stick all these materials together with a silk like substance they secrete. Only the head and abdomen is able to come out of this special case, its abdomen is held inside with two little hooks. Both types of Caddisfly larvae breathe through fragile gills located on either side of their abdomen. Some species prey on animals, most feed on plants. They can mainly be found in the middle of a river as they have special silk secretions that help them to 'stick' to the stones found in the middle of the riverbed and not be washed away. These creatures range in colour from yellow and green to brown and curl up slightly when placed on a flat surface. Some Caseless Caddisfly Larvae can spin webs with their silk secretions and filter food particles from the water. There was only one Caddisfly found- a Caseless one, the reason for this result either comes down to misidentification or it is possible that a real invertebrate was found.
Leeches
Leeches have 34 segments in their bodies and are very much like worms. Leeches are very irritating creatures, however, some farmers appreciate them as they provide fine food for fish. Their adaptation is a sucker that is attached to both ends of its body (depending on which species); this body part assists them in sucking blood out of other organisms or to suck onto stones. Most species that are found in freshwater prefer the slow moving edges of the river even though most can be found at the middle as they are probably looking for food. This is why many of them are found in the middle of the stream, there were 4 found at the edge and 3 in the middle in the total of all 7 group's results. Their saliva contains an anaesthetic and an anticoagulant (a substance which prevents blood clotting) so the victim doesn't feel the mouthparts enter and so the blood doesn't clot. When the leech has decided it has had a sufficient amount of blood it will let go. One species of leech have sharp teeth attached to their jaws making their bite more powerful. The power of their suck is so strong that if one attempts to pull it their slippery skin will cause one's hand to slide off, when they are pulled they will most probably suck harder. Leeches are excellent swimmers; they swim in an unsteady pattern.
Burrowing mayfly nymphs
Burrowing nymphs burrow in the stream bottom sediments and are usually longer and lighter in colour than the other types of mayfly nymphs. This type of nymph has the characteristic of three tails, though tail length may vary from nymph to nymph. They are elongate, usually flattened insects with well-developed legs, medium to long antennae, gills along the abdomen, and two or three long, antenna-like filaments at the posterior end of their body. The gills of most species are leaf-like, with branching trachea visible within. The presence of gills along the abdomen distinguishes mayfly nymphs from immature damselflies and from stonefly nymphs. Most species need a well-oxygenated environment, as the water in the Tillingbourne River was saturated with oxygen this was a very good place for them to reside
Freshwater Shrimp
The adaptation of freshwater shrimp that distinguish them from many other freshwater invertebrates is that they are streamlined. They were the most commonly found invertebrate- a total of 402 were found at the edge and middle of the river by all 7 groups. The young freshwater shrimp molt quite a number of times during their youth, my group found 3 exoskeletons, 2 at the edge and 1 in the middle. The ones at the edge may have been washed away or recently shed, as the water was moving. The one in the middle may have washed from the side and since the water was not that powerful that day it may not have travelled far. Since freshwater shrimp have no real way of self-protection, apart from camouflaging, they hide in the vegetation. Many can be seen swimming about and most inhabit the middle of the river, as it is quite easy for them to swim with their streamlined shape. They have two pair of grasping legs near the head, five pair of legs for walking at mid-body, three pair of ciliated leg like appendages for swimming on what would be the abdomen, and one pair of hind legs to assist with eating in a curled position at the tail. They have eleven body segments (one for each set of appendages). The head has two longish antennas and the tail section has two short protrusions. The legs of the shrimp are constantly in motion to circulate water over their gills. They quite frequently stop for gasps of breath after swimming a few inches, when doing this they sink to the bottom of the river a bit then rise up giving them an odd wavering swimming movement.
Anomalous results-
The biggest anomalous result was the amount of freshwater shrimp. There was a total of 402 shrimp found at the middle and edge of the river by a total of the 7 groups. The amount of freshwater shrimp made up almost 62% of the total invertebrates in that freshwater stream. To conclude that 62% of the population of that particular ecosystem is of freshwater shrimp because as these streamlined species are extremely fast swimmers they can move swiftly and there were other invertebrates that successfully managed to avoid getting caught in the net. There were varied results in the amount of freshwater shrimp caught by the various group, therefore making it difficult to work out an approximate average of how many shrimp there were. One group caught 1 at the edge and another caught 100 making this a highly anomalous result for all groups
Another anomalous result was the number of swimming mayfly nymphs, although a certain concentration of these animals were expected there was an extraordinarily amount discovered by Group 2 i.e. 25 at the middle and 50 at the edge. There were a total of 13 found at the middle of the river by 3 other groups, this was an expected amount. There maybe a variation in the reasons why Group 2 came up with a different result as opposed to a 'reasonable' one but the main two are possibly misidentification and the adjustment of results.
Another unexpectedly high number of invertebrates in the same species is the damselfly nymph group 4 found a total of 14, which is 87.5% of the total number of damselfly nymphs found. I think this is mainly due to the misidentification of the creatures. Another particularly odd anomalous result I found was that one group found a hydra and as this type of animal is rare in freshwater I find the result incorrect.
Beetle larvae, which are hardly found showed an unexpected result of 21, found at the middle of the Tillingbourne River. From our supervisor we learnt that this was a highly incorrect figure as there were very few beetle larvae ever found at that particular river.
The number of nymphs found is also very much different to other families of invertebrates. There was a total of 150 burrowing mayfly, swimming mayfly, damselfly and stonefly nymphs found this is a relatively large number compared to the amount of larvae found.
My group - group 3- we recorded a 0.85 m/s result for our flow rate whereas the mean of the other groups excluding ours was 0.296 and the mean including ours was 0.375. The reason for this anomalous result may be because of an incorrect following of the method or a misrecording or simply that the area where the results were being recorded in a contaminated area meaning the water was walked or waded through and the flow disturbed.
There may be other anomalous results that I did not mention but as I am not a freshwater ecologist I do not know what type of invertebrates and which species are expected to be found.
Evaluation
Overall I feel that this experiment was successful in that we developed a certain standard of knowledge in freshwater ecology. However, these results were not as accurate as we would have hoped for them to be. I feel that the biggest mistake we all made was the misidentification of the invertebrates we found. The fact that we were pressed for time and inexperienced in such observations contributed greatly to our flaws.
Sources of Error
There were a few sources of error and poor judgement in our investigation. Below is a list stating the four main ones and describing why I feel it was an error.
The sampling from the tray- when we were taking the invertebrates from the pan and putting them into the jars with lids, we may not have brought all of them with us. This is not fair testing. Next time we should have a bigger jar, which will enable us to take everything from the pan. When we took the invertebrates from the pond net to the pan we might have also left some invertebrates in the net, this also is not fair testing.
Contaminated samples- the middle section of the riverbed may have been disturbed when people were walking through it. The invertebrates that inhabited this area would have fled from it in the interest of their own safety and went either further down the stream or to the edge. This might have increased the number of invertebrates at the edge. Organisms such as Freshwater Shrimp and Nymphs are good swimmers so once they have found that their habitat is being disturbed they would've fled to the edge of the river. However, one could argue that most invertebrates are better suited and adapted to live at the edge because of the difference in the velocity of the water and the stones, mud and silt in the different places of the river.
Pressure used in 30-second kick sampling- the same person or people should have kicked with the same pressure at the middle or edge of the river. The difficulty of doing this is that it is difficult to measure the pressure at which a person can kick. The same movement in kicking and the direction in which they go should also be the same or at least similar at the edge and middle of the river. In my group, there were two people who kicked at the edge and the middle, but I doubt that we kicked with the same pressure and at both sides. The consequences of this is that we may have disturbed more invertebrates at one section of the river more than at the other and this would have been a very bad source of error and once again not fair testing.
Misidentification- this was probably the biggest error even though it has nothing to do with fair testing. The misidentification of the freshwater invertebrates- and many other animals for that matter- is the most common problem. As we did not have as much time as we would have liked to identify the invertebrates, many people rushed and did not follow the key we were given properly. Some of the biggest mistakes were the unexpected number of damselflies, the inadequate number of other invertebrates and the number of invertebrates which had never been discovered before.
Incorrect recordings due to lack of attention- people may have not given their full attention when reading. An example of this is: Our group had an anomalous result for the flow rate, as did Group 5. The flow metre may not have been used properly because the propeller may have gotten stuck for a period of time and nobody noticed- because of lack of attention- then it continued or the time may have been recorded incorrectly or when the results were recorded they may have been misunderstood.
What I would redo if presented with the opportunity to do this experiment again
There are a few things I would redo if given the opportunity to redo the experiment. Below is the list, in order, of what I would like to do:
Make sure that everything is brought back that was caught in the net by pouring water through it and shaking it thoroughly
Make sure the middle sample is taken first
Make sure the area the sample is being taken from was not previously contaminated
Ensure the same person or people kick in the same pattern and as accurately and similarly to one another each time
If unable to identify an invertebrate ask a reliable person who is
Spend as much time as possible identifying the invertebrates
Follow all rules of fair testing e.g. time recordings equally and perform the same research for everything
When taking the oxygen levels ensure that the oxygen metre is placed gently in the water and the oxygen levels are measured accurately.
When measuring the flow rate make sure the hydro prop flow metre is positioned properly and handled similarly at both sections in the river.
I think that the methods used were quite accurate. However, nothing is perfect. There are still a few attributed to the methods that could have been perfected. One of these is the kick sampling. I think that instead of using our feet for the kick sampling we should have a fan-like machine that spins around the riverbed disturbing the invertebrates equally on both sides and making sure that none of them are killed. This will make the kick sampling method as accurate as possible. The machine should also have a timer so it can automatically stop after the 30-second period has terminated.
As I mentioned previously, another problem is the recording of the results. Some people may have felt that all the predictions/ hypotheses made were true and when they got their results they may have feared that they had the wrong results and so adjusted their results to their neighbours' or someone else's.
Time was also an issue. I feel that we should've been given a longer period of time in which to measure the oxygen levels, velocity, and temperature of water as well as do the kick sampling. Our groups were small so we had to work economically and efficiently. This may have affected our results to an extent.
The quality and accuracy of the observation is one of the things, which are not fully correct. As we are not professionals in river studies, many of our measurements and results are possibly incorrect. I am not entirely confident that the results achieved are highly reliable. The results depended on teamwork and a certain level of understanding in the subject matter. We all worked individually as well as in a team and if we were given the opportunity to do the research again I think that there would be a significant increase in the standard and quality of the work produced.
Many of the anomalous results are due to the fact that as inexperienced freshwater ecologists we were more prone to make mistakes and the suitability of our methods were accurate enough for the research we performed but I feel that if we used more developed methods and machines to record our research. For instance, an Impellor that had its own timer, which started in accordance to when the propeller starts moving. And a machine, which gently goes in the water gently without contaminating the sample. The best solution for the prevention of the contamination of the results is for everybody to have a very big gap between them and another group. Furthermore, I think that by recording some of the other, slightly more detailed, abiotic factors we would be able to get a clearer perspective on things that affect the distribution and abundance of freshwater invertebrates in that ecosystem.
Bibliography
I used the following two books as my secondary resources for this research:
- Biology by Mary Jones and Geoff Jones
- Biology for Life by MBV Roberts
I used the following websites in my research:
http://www.state.ky.us
http://www.biology.usgs.gov
http://www.biology-online.org
http://www.flyanglersonline.com
http://www.missouri.edu
http://www.enn.com
http://www.naparcd.org
http://www.wellfleetbay.org
http://www.agrifor.ac.uk
http://www.seven-creeks.com
http://www.seanet.com
http://www.biol.vt.edu
