Macroinvertebrates are described as organisms who lack a backbone but can be seen with the naked eye. These taxa are able to inhabit a variety of habitats including running waters like streams (EPA 2012). Macroinvertebrates generally are affected by various different physical and chemical conditions. If there is a change in the quality of the stream water, such as a change in the flow due to a dam or a pollutant from disturbances in the area, then there could be a change in the macroinvertebrate community (Roy et al 2016, Heatherly II et al 2007). Or if there is a presence of an invasive species in the ecosystem, this could also greatly impact the community. Droughts and excessive drying can also greatly impact the macroinvertebrate community due to the flow of the water. This could impact the magnitude of the velocity present in the stream, shifting the macroinvertebrates present (Lynch et al 2018).
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Therefore, the leaf source in the surround area of the stream can greatly affect the richness of the composition in the macroinvertebrate community. Deciduous and Coniferous trees’ chemical composition can greatly affect the nutrient cycles involved in stream communities (Thieme et al 2019). The leaves allow for organic compounds to be filtered into the stream, but there is also the release of bacteria and invertebrates as well. Coniferous leaves have a composition that is dominated by ligin-like formulae, while deciduous trees have a balanced amount of both tannin and lignin molecules. Both tree species however do not have a high rate of lipids, amino acids, and carbohydrates in their molecular composition (Thieme et al 2019).This could also lead to the hypothesis that different varieties of leaves will impact the macroinvertebrates in a different manner. The aim of this study was to further investigate whether two different types of leaves would depict if there was a change in the colonization of the macroinvertebrates in the Parkville Nature Sanctuary stream. We predicted the deciduous would have a great diversity of macroinvertebrate taxa in comparison to the coniferous leaves.
Materials and Methods
The initial step in the procedure consisted of forming leaf packs to be put in the stream. The collection of leaves was from various neighborhoods in the metropolitan area in Kansas City, MO. The leaves were collected from two types of trees in the region: Deciduous and Coniferous. These trees are among some of the most common species in Kansas City. The removal of the leaves was done by hand and put into large gallon sized zip lock bags. The leaf packs were made by placing about thirty grams of each type of leaf in a mesh bag. The mesh bag included an identification tag and was then secured with a double know near the top of the mesh bag. There was a total of 12 bags, with 6 being deciduous leaves and 6 being coniferous leaves. The leaf packs were then put securely in the stream at the Parkville Nature Sanctuary. The Parkville Nature Sanctuary is located in Parkville, MO at a maximum elevation of 1008.33 feet. The sanctuary consists of 115 acres of area and 5 streams throughout the outdoor trails.
In various areas, the stream was ranging between the top, middle, and end of the 10 m section of the stream. The stream had a top width of 3 m 38 inches, middle width of 4 m 20 inches, and bottom width of 76 inches. The stream has a clear-brown tint to the water due to the mud in the stream. There was also a noticeable odor present with a fishy smell. The leaves were submerged in the stream from March 20, 2019 to April 17, 2019. After the duration of 4 weeks, the deciduous and coniferous leaf packs were removed from the stream to be analyzed in the lab. The sorting of the leaves were first separated into each treatment and labeled. The packs were then examined for various macroinvertebrates. The macroinvertebrates were then placed into petri dishes to be organized into orders and the number of each taxa was recorded. After the completion of the examining of the leaf packs, the diversity was calculated per pack of leaves, A statistical analysis was then completed to further conclude if there was a difference in the diversity that was significantly different in the macroinvertebrate community.
The Shannon-Weiner Index was used to calculate the diversity metrics in the leaf packs in regard to diversity, richness, as well as evenness. This index allows the ability to calculate how the distribution of a taxa is in an evenness perspective. The index also allows for the quantification of the structure of the community. This shows to be an advantage to traditional methods of counting because there is a great effect on the diversity of the sample when the sample size is larger. The equation for the Shannon-Weiner index calculation is:
With the S being the total number of taxa in the community, known as richness, and pi stands for the proportion of observations in the
represents the evenness of the taxa using the equation:
J’= H’/H ́max
Shannon’s index is therefore unitless and is mainly used to obtain an estimate of diversity (Boyce 2005).
To further analyze the cumulative percent of the macroinvertebrates, the Kolmogorov-Smirov Test was used to calculate the
. This is a nonparametric test used to determine whether two samples, in this case the leaf pack treatments from the deciduous and coniferous trees, are from distributions that are the same. The
is then used to compare the differences in the maximums,
. This statistical calculation increases in the precision and accuracy of the D estimates when there is a great number of samples collected (Boyce 2005).
At the beginning of the conduction of the study, there were 12 leaf packs submerged into the stream at the Parkville Nature Sanctuary. However, upon retrieving the leaf packs, there was only 5 leaf packs remaining. This could be due to the excessive amount of rainfall over the previous weeks in Parkville, leading to a greater amount of velocity in the stream. When calculating the Shannon-Weiner Diversity Index, the deciduous treatment consisted of 6, which represents S, the total number of taxa in the community. H’, or evenness was 1.3559, while the natural log of maximum evenness, H’ max, was calculated to be 1.7918. The diversity, J’, was 0.7567. The taxons observed in this treatment consisted of penny beetles, crane flies, aquatic spiders, snails, clams, mussels, leeches, damselflies, and pillbugs. In treatment 2, the Coniferous leaf packs displayed a S factor of 5, with a H’ of 1.0374. The H’max calculated was 1.6094, while the J’ was 0.6446. The taxa observed in this treatment consisted of crane flies, pill bugs, snails, clams, mussels, and damselflies.
When calculating the Kolmogorov-Smirov test, the differences in the absolute values were taken of the cumulative pi , to then obtain the
. When obtaining the
, the number calculated was 0.1690, while the
at a 0.05 significance level was 0.4285. Since
was less than
, we would fail to reject the
, the null hypothesis. Although Deciduous trees are seen to have a richer taxa, as seen in Figure 2, the curve does not reach 100% until rank 6, while Coniferous trees reached 100% at rank 5 (Figure 2). This would entail that the two leaf treatments overall have the same diversity and do not have significant differences in the taxa observed.
Figure 1: Rank Abundance curve of the Macroinvertebrates: Shows the trend of macroinvertebrates observed in both deciduous and coniferous leaf packs. This depicts there is an increase in taxa in coniferous leaves, which then reaches a peak and levels out.
Figure 2: Shows the various macroorganisms observed in the Coniferous and Deciduous leaf packs. In Coniferous leaf packs, there was mainly crane flies in the Coniferous leaf packs. There was a large number of clams and mussels, as well as 5 other taxons represented in the Deciduous leaf packs.
The study of the leaf packs consisting of deciduous and coniferous leaves yielded a great number of results. The leaf pack with the greatest yield of macroinvertebrates was the deciduous leaf pack, followed by the coniferous leaf pack. There was not a statistically significant difference in the diversity of taxa between both leaf packs. However, Coniferous trees reached 100% in the abundance curve at rank 5, while Deciduous trees reached 100% at rank 6. This could be due to coniferous trees having a greater rate of dissolved organic carbon in their concentrations. The greater rate of organic carbon could be due to the increase in the number of macroinvertebrates inhabiting the Coniferous trees (Thieme et al 2019). This would suggest that macroinvertebrates are able to inhabit Coniferous leaves at a greater scale than Deciduous. Another addition to the organic carbon factor is the limit in the availability of nutrition in the leaves. This could highly affect the macroinvertebrate community because the concentrations of the organic matters can determine the number of taxa inhabiting the area. Also, the deciduous leaf packs that were collected from the streams were more densely packed and had a mud consistency in comparison to the coniferous leaf packs. This could suggest that deciduous trees are native to the Parkville Nature Sanctuary and could be the most beneficial in terms of biodiversity.
- Boyce, R. 2005. Teaching Issues and Experiments in Ecology. 3, 1-16.
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- Lynch, D. T., Leasure, D. R., and Magoulick, D. D. (2018) The influence of drought on flow-ecology relationships in Ozark Highland streams. Freshwater Biology63, 946–968.
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