We studied how human land use effects fish population and diversity in nearby creeks. We collected data concerning the different species of fish and the total number of fish present in Collins Run and Harkers Run on two different occasions with Dr. Donna McCullum. We utilized the technique of “fish shocking" in order to catch fish in two areas on each creek so that we could count how many species of fish are present in each area and the total number of fish in each area. These numbers helped us decide whether or not each creek has a healthy amount of fish diversity. After taking all our data used the Shannon Index of General Diversity to decide which test sites have better biodiversity. There have been many other studies run in various parts of the world in which this same shocking technique, and the Shannon Index were used when studying fish diversity and how human development affects it.
For our semester research project we studied the effects that human urbanization has on fish populations. Our project was localized since we conducted tests in two creeks, Collins Run and Harkers Run, which wind through Miami's campus. The main question we tested was "how does the environment around the creek affect the fish populations?" We believe that the more human urbanization there is present near the creek, the smaller and less diverse the fish population will be. We decided to research this topic after going on the creek walk up to the Bluffs. We quickly realized that we all enjoyed walking through the creek and the serene setting the creek provided. We are also interested in the chance to learn how we affect the natural environment. We also hope to find correlations between our research results and results obtained in other international research. As we conduct our testing we will learn what characteristics define a healthy fish population and what elements are needed for a healthy stream ecosystem. We believe this knowledge will aid us in drawing conclusions which will help us solve our main problem. In the end we believe this project will help us achieve a greater appreciation for the environment we live in here at Miami, as well as at home, now and in our future.
Relevance of our Research Question
After conducting background research we found numerous equations which helped us evaluate the biodiversity of our test sites. We utilized the Spearman Rank Test in Statview, to illustrate the composition of the species abundance within the populations of the two creeks. We also used Statview to determine whether or not the species compositions of our test sites are similar or significantly different.
The second equation we utilized was the Index of Dominance, which illustrates the health of the two separate creek systems. The values range from 0 to 1, the lower values show that the dominance of species is more evenly dispersed throughout the population, whereas the values closer to 1 illustrate that the dominance is shared by a fewer number of species. A sign of an unhealthy creek system is dominance of a single, or few, species as opposed to a more evenly dispersed population concentration.
ni = number of individuals per species
N = total number of species gathered
C = the number of species common in both sites one and two
A = number of species found in site one
B = number of species found in site two
H = -∑(ni/N)log(ni/N)
Ni = Importance value (number of individuals)
N = Total of importance values
Calculating the biodiversity of our test sites is not the only factor that past studies have shown as important when studying how human urbanization effects fish population though. We had to also take into consideration many of the different elements of the stream’s ecosystem. Most of the characteristics we noted which affect the stream’s ecosystem were also sampled in a study in North American Journal of Fisheries Management. In this study they measured “bank width, stream width, depth, velocity, clay substrate, silt substrate, sand substrate, fine gravel substrate, coarse gravel substrate, rubble-cobble substrate, boulder substrate, cover for fish shading, minimum and maximum bank heights, and bank erosion." (Simonson, Lyons, Kanehl, 607). We also took data on all of these characteristics except “bank width." “cover for fish shading, minimum and maximum bank heights, and bank erosion." Another study noted in Landscape Ecology also touched on the importance of substrates, velocity, and depth variability, as well as, expressing an importance in the presence of pools, riffles, and bends in the stream (habitat variety). And the River Habitat Survey, which collects “information about the physical structure and habitat quality of streams and rivers in the UK" (Jeffers, 1998), states that it is important that researchers test sites which contain the full variation of physical characteristics (pools, riffles, etc.) present at the stream being studied so that a correct sampling of the full population is found. These articles were taken into consideration in our study as we made sure that each test site had a habitat which contained pools, and riffles.
Facts which show how the land use outside of the stream effects the fish in the stream are stated in articles included in volumes of Landscape Ecology and Fisheries. Landscape Ecology states that the absence of organic litter (i.e. leaves from nearby plants) reduces the heterogeneity of depth, substrate, and current velocity thus causing streams with little structural complexity. Adding this fact with the already stated fact that habitat variety is necessary in a healthy stream ecosystem shows that human urbanization which gets rid of plants near streams will cause the entire aquatic ecosystem to “lose" its variety and no longer be healthy. The threat of human urbanization is even further magnified with the fact stated in Fisheries that “93% of declining fish taxa are suffering from habitat loss/destruction" (Williams,7) and the causes of this destruction is often “physical and chemical degradation" such as urban and agricultural encroachment (Williams, 8). Human changes which alter the natural environment’s vegetation and landscape patterns thus have a huge affect on fish population health (Blois et al., 2001).
There are also many facts in past studies which we find interesting that relate to our study. A fact we found interesting in Fisheries is that the nine most diverse families of freshwater fish are minnows, perches, suckers, billifishes, livebearers, bullhead catfishes, salmon/trout, Mexican livebearers, and sunfishes"(Williams, 7). We thought it was interesting because even though we were testing in a small stream we found fish in two, minnows and sunfishes, of the nine categories. We found an interesting study very similar to our project in which a group of students in Maryland studied the “long term changes in stream due to land use" by building models of streams. A studied conducted in eastern North America noted that a large population of the creek chubs (semotilus atromaculatus) can help identify stream areas in which there are environmental stressors, such as human urbanization (Fitzgerald et al, 1998). We also found interesting projects that were similar to our project in previous years in natural systems, such as "The Effect of Landscape On Streams and Their Behavior as Corridors" and "Erosion On the Creek Banks (the mudslides)." And lastly, a fact stated in Biological Monitoring of Fish helps make a connection between our study of the fish population and the entire aquatic ecosystem. This fact is that “fish play a central role in bio-monitoring because they are the top of the food chain in most aquatic ecosystems, and their presence shows other organisms are in the ecosystem." This statement relates fish to the larger picture of the entire stream ecosystem. Our research relates to the larger question of how well do humans need to monitor their land use around the world? We hope to contribute the knowledge of how much our land use affects aquatic life, even in a small community such as Oxford. This information may then be combined with other studies to expand our knowledge of the interactions between humans and the environment on a large scale.
Materials and Methods
The first step in our experiment was to go out and find two places in each creek which are all very similar in water current, water depth, and creek width and which all contain riffles, pools, and similar substrata. With the creek areas acting as our constant variable we were able to focus more on the variable of human land use. We completed our field work with Dr. McCullum and her shocking technology. We used the shocking technique in each area and counted the number of fish and different species in each test area. This is the data we used in our statistical analysis in statview. In our testing we weren't able to take some factors such as pollution (due to lack of chemical testing ability), light and shade (since the lighting will change during the day this won't make a difference), or other animal influence (because it would be nearly impossible to track all nearby animal life) into consideration. Below is a link to the main data table that we are used during our collection of data.
We believe that our data is statistically sound because all of the numbers that were added and manipulated were in equal units (such as meters), and because all data was carefully collected. We made sure that most of the environmental factors, such as water depth, creek width, water current, and testing area length, were constant in an attempt to eliminate all biases. To make sure the class’ data was trustworthy we put the students in groups of more than one person for each task (so there was more than one person counting each thing, ensuring accurate results) and then compared the numbers each person found with their “partner’s" nubmers to make sure there was a clear correlation. We believe our collection methods were adequately shown through our documentation of our field testing in photos and videos which were shown to the class during our student lab presentation.
The "fish shocker" was our most important tool since it was necessary in order to count and classify the different types of fish living in each area. In our attempt to make sure that all testing areas were similar we used a measuring tape to measure the stream depth, stream width, and the test area’s length. We also used a ping pong ball, string, and stopwatch to test the water's velocity by timing how long it takes the ping pong ball to float down the stream from one point marked by string to another point marked by string. Donna McCullum’s knowledge of fish species was also imperative as we classified the different types of fish.
In the student generated lab the students measured all the environmental characteristics present around our testing areas (water depth, average creek width, current, creek bed composition). After dividing the students into groups of two or three we gave half of the class the tasks of checking the environmental characteristics at one testing site while the other half of the class tested another site. This was done simultaneously with half of the class at Harkers Run and the other half at Collins Run. After they collected all the data each half of the class compared all the measurements from their area to check accuracy. We did not ask the students to process any data because they did not test all four sites.
Our habitat analyses proved that the two sites on Harkers Run and the two sites on Collins Run are all similar to one another. The average depths and widths were comparable, Collins having an average depth of .35 meters and an average width of 4.76 meters, and Harker having an average depth of .49 meters and an average width of 7.49 meters. These numbers can be viewed in our habitat datasheets.
After testing all four sites we compiled data sheets that displayed the number of species and total number of fish found at each site. These sheets can be viewed at species datasheets.
The Index of Dominance for Harkers Run was .194, whereas, the value for Collins Run was .233. Since the value for Collins Run is higher than that of Harkers run, we can state that the population of Collins Run is shared by fewer species than in the case of Harkers Run.
The Index of Similarity for the comparison of Harkers Run, sites A and B, was .72, illustrating that the population of species is very similar between the two sites within the creek. The value for sites A and B on Collins Run was .56, also suggesting that the species population between the two sites on Collins Run were similar. We used the Index of Similarity to compare the two creeks, as well. The value calculated for this comparison was .706, therefore, the species population between Collins and Harkers are also similar.
We calculated the Shannon Index of General Diversity for both sites on each creek, as well as the value for both sites combined in Collins Run and Harkers Run. The value calculated for Collins Run, site A, was .569, and the value for site B was .973, illustrating that site B on Collins Run is more diverse than site A. The calculated value for Harkers run, site A, was .835, and the value for site B was .756, showing that site A is more diverse in the case of Harkers Run. Our comparison of the two creeks, using the Diversity Index resulted in a validation of our hypothesis. We calculated a value of .784 for Collins Run and a value of .888 for Harkers Run. Since Harkers Run was the creek with less human intervention, and its calculated value of diversity was higher than that of Collins Run, the creek with more human interaction, these numbers prove that human urbanization does have negative effects on fish population.
Interestingly, the most disturbed site (Collins Run "B") is the most diverse site.
Discussion and Conclusion
When we reviewed our graphs, we found it strange that Collins site B had a larger and more diverse fish population. This greatly differed from site A, which was fairly large but consisted of only a few species. Looking at the substrata, we found the cause of the skewed results. Present in site B of Collins Run were pipes, a very deep pool, and a large cement block. Since humans had disrupted this environment, it was more diverse and therefore had a larger variety of fish. However, this greater diversity doesn’t prove that the population was healthy at Collins site B, because we found a Hybrid Sunfish, which is a sign of stress in the habitat.
Another sign of stress in Collins Run overall is that its large fish population is shared by fewer species and is greatly dominated by Central Stonerollers (compostoma anomalum). A healthy creek environment has a large population of fish that is equally distributed amongst many species. The Index of Dominance we calculated proves this. Collins Run had a value of .233, and Harkers Run had a value of .194. The index goes from 0.0 to 1.0, 0.0 meaning the population is shared by very few species, and 1.0 meaning the population is shared by many species. Therefore, the population in Collins run is shared by fewer species than that of Harkers. Also Harkers Run had a smaller number of creek chubs than did Collins Run in both site A and B, which shows that environmental stressors are present in the areas (Fitzgerals et al., 1998)
The Index of Similarity helped to show that the sites we tested were similar to each other, which was important to use as a control. This index goes from 0.0 to 1.0 as well, 0.0 meaning not similar at all and 1.0 meaning very similar. For Collins A v. B the value was .56, while the value for Harkers A v. B was .72. Their combined value was .706, meaning we chose sites that were fairly similar to each other in terms of fish population.
Lastly, the most important equation was the Diversity Index. This helped us to prove our hypothesis mostly correct. The range was also from 0.0 to 1.0, with 0.0 meaning not diverse and 1.0 meaning very diverse. Collins A had a value of .569; Collins B had a value of .973. Site B, as mentioned previously, is very diverse as a result of human influences. Harkers A had a value of .835; Harkers B had a value of .736. When sites A and B were combined, Collins had a combined value of .756, and Harkers had a combined value of .835. This shows that Harkers Run is more diverse, which proves our hypothesis because Harkers Run was the creek with less human urbanization present.
Our study correlates with anyone researching the effects of humans on the environment, and the changes of species life and diversity as a result of urbanization. This doesn’t have to be directly related to fish or aquatic life; it can be compared to any living organism in the natural world.
A way that our lab packet can be utilized is as a guide to categorizing data. Our data sheets are good examples of the organization which we found was the best when completing our calculations. Also, our equations are basic and can be used by most people to analyze their data.
Additional questions we would like to possibly research:
1. If we had investigated the vegetation of the creeks more thoroughly in another time of year, such as the spring, would it change our data?
2. How would our understanding of, or results differ if we would have taken into account plant species and rock types?
3. Had we investigated the fish species, would we know where each species would be more prominent?
4. How does pollution or other chemical variants in the water or nearby environment effect the fish population?
For further investigation, we would test more sites on each creek and take more habitat data for each site. When researching, we would answer the questions above to help us gain more understanding on our topic.
We had a lot of fun testing in the creeks and learning about fish populations and stream environments. Our hypothesis that "the more human urbanization there is present near the creek, the smaller and less diverse the fish population will be" was proven as mostly correct except for our belief that human intervention would create “smaller" fish populations too. Had we simply stated that we believed human urbanization would cause fish populations to be unhealthy our hypothesis would have been completely correct. However, we believe that this experiment was an overall success which taught us a lot about streams and the fish that live in them.
October 6th - we will collect maps of the creek area and search for similar sections to test.
October 8th - we will meet with Dr. McCullum about the shocking technique and set up dates to use the equipment
October 13th, and 27th - we will meet and hopefully be able to test the 6 different areas we have chosen (weather and equipment permitting)
Environmental Toxicology and Ecotoxicology found at http://www.bio.hw.ac.uk/edintox/enviro.htm
Maryland Virtual High School Stream Modeling Project http://www.nehs.org/pages/streamproject.shtml#Project%20Description
Ourso, Bob. Species Diversityhttp://marisa.aquabio.swt.edu/ecology/notes/spdiversity/spdiversity.html
Hocutt, Charles H., and Jay R. Stauffer Jr. Biological Monitoring of Fish. Lexington, MA: D.C. Heath and Company, 1980.
Williams, Cindy Deacon Fisheries. “Substainable Fisheries Economics, Ecology, and Ethics"
Simonson, Timothy D., Lyons, John, and Kanehl, Paul D. North American Journal of Fisheries Management Vol. 14. “Quantifying Fish Habitat in Streams: Transect Spacing, Sample Size, and a Proposed Framework." 1994
Roth, N.E., J.D. Allan, and D.L. Erickson. Landscape Ecology. Vol. 11. “Landscape Influences on Stream Biotic Integrity Assessed at Multiple Spatial Scales."
Fitsgerald, Dean G., Lanno, Roman P., and Dixon, D. George. Ecotoxicology Vol. 8 “A Comparison of a Sentinel Species Evaluation Using Creek Chub (semotilus atromaculatus Mitchill) to a Fish Community Evaluation for the Initial Identification of Environmental Stressors in Small Streams" 1998
De Blois, Sylvie, Domon, Gerald, Bouchard, Andre. Landscape Ecology Col. 16. “Environmental, Historical, and Contextual Determinants of Vegetation Cover: A Landscape Perspective." 2001
Jeffers, J.N.R. Aquatic Conservation: Marine and Freshwater Ecosystems Vol. 8. “The Statistical Basis of Sampling Strategies for Rivers: an Example Using River Habitat Survey." 1998
Cummins, Hays. “Paleoecology Problem Set: Help Sheet" 2001
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