Sangamon Samples: Aquatic Entomology and RiverWatch Report
Tristen Ting & Robert Tu
University Laboratory High School
Entomology (Fall 2024)
Mr. Millán
November 6, 2024
Introduction
​
Within aquatic environments, watersheds play important roles in irrigation and organism
habitats. Furthermore, they are an important aspect in understanding the impact of the water
source on the ecosystem around it. A watershed is the surface drainage area that contributes
water from runoff to a lake, stream, river, groundwater supply, coastal waterbody, or other body
of water. Watersheds are delimited because the bodies of water in a watershed must be
connected. “Riparian zones are lands that occur along the edges of rivers, streams, lakes, and
other water bodies. Examples include streambanks, riverbanks, and floodplains.”(National Park
Service, 2022). The health of a watershed plays a large part in the health of the riparian zone and
the subsequent environment surrounding it.
Riparian zones provide habitat for a diverse amount of organisms that live in the stream.
The water quality is maintained because vegetation on the riparian can remove excess sediment
and nutrients from the water. The riparian also stabilizes the stream banks and reduces flood
water velocity. ​
​
The Illinois RiverWatch program is a volunteer stream monitoring program administered
by the National Great Rivers Research and Education Center. This program focuses on
monitoring streams to study the health and ecology of large rivers and making discoveries related
to the nature of watersheds. The three primary goals of the Illinois RiverWatch program are to
provide consistent high quality data that scientists can use to measure how the conditions of our
state’s streams are changing over time, to educate and inform Illinois citizens about the ecology
and importance of Illinois water resources, and to provide an opportunity for citizens to become
involved in the stewardship of the state’s rivers and streams. (Illinois RiverWatch, 2021).
Through monitoring the richness (the number of species in the environment) and density (the
abundance of each species), the program can accurately observe and watch over the Sangamon
River and other bodies of water and environments that they take care of. The Illinois RiverWatch
program focuses on specific organisms to indicate if things are wrong. These are called indicator
organisms, and the indicator organisms used by Illinois RiverWatch are benthic
macroinvertebrates. These are animals that spend at least part of their life cycles in or on the
bottom of a body of water, are big enough to see with the naked eye, and do not have backbones.
(Illinois RiverWatch, 2021). Specifically, these organisms include mayflies, stoneflies,
caddisflies, midges, and beetles to be used as indicator organisms. RiverWatch also uses five
different health indices to assess the quality of a part of a river. These indices are the number of
organisms collected, organisms sampled (the total number of indicator organisms collected or
subsampled), the taxa richness (the total number of taxa identified in a sample), the EPT taxa
richness (the number of Ephemeroptera, Plecoptera, and Trichoptera taxa present in a sample),
and the MBI (calculated level of organic pollution by dividing the taxa index by the total number
of organisms sampled). A combination of these five indices gives RiverWatch a good idea of
how healthy their sample location is. Monitoring bodies of water for a long amount of time
provides data for scientists to identify problems or trends in biodiversity and water quality, and
analyzing this data frequently can ensure that the environment affected by the Sangamon River
and connecting water sources stays healthy and is maintained.
The Sangamon River is part of the Mississippi watershed. The location where we were
sampling was a 2nd order stream because of its connections to multiple order 1 streams. The
water in the Sangamon River drains into the Illinois River, and finally reaches the Mississippi
River. The portion of the Sangamon River that we collected samples in had a soft-bottom
substrate, and the water flowed West. From the United States Environmental Protection Agency,
the aesthetic quality and aquatic life of the Sangamon are rated ‘good’, the fish consumption rate
is unknown, the permitted discharges include biosolids, sewage and natural gas, and the
identified issues include bacteria, low oxygen, and degraded habitat. (U.S. Environmental
Protection Agency, 2024). The health of the Sangamon River can have a large impact on the
environment surrounding it. Because everything is connected, it’s important to keep clean and
maintain watersheds like the Sangamon to ensure the larger bodies of water like the Mississippi
watershed stay healthy. The health of the Sangamon River directly affects the health of the
Mississippi through a multitude of different aspects including pollution/water quality, erosion,
and biodiversity. Pollutants within these rivers like nitrogen or metals can damage downstream
environments and habitats.
Procedure
For our RiverWatch survey, we sampled a downstream portion of the Wildcat Slough
(Figure 17) using a snag technique with a bucket and D-frame nets. We selected the undercut and
snags to sample specifically because they had the most biodiversity. We followed RiverWatch
sampling protocols including collecting from submerged logs and only sampling relevant
organisms. (Illinois RiverWatch, 2021). Our group (table 4) collected a sample that had both
adult insects and larvae. Through the method of shaking insects from the snag into our collection
nets, we filled our bucket with organisms and later preserved them in insects to identify.
Results
​
At the location of the sampling, the river substrate was soft-bottomed. When surveying
the stream, we chose to survey snags and undercut stream banks specifically because these areas
consist of higher biodiversity compared to surveying sediments. Collecting samples in areas with
high biodiversity will give us accurate results of the health of the Sangamon. While sediment
areas can provide poor data and don’t suit well for insect habitat, snags and undercut stream
banks both provide typical habitats for lots of aquatic insects within the Sangamon River.
Ultimately choosing these sampling methods gave us accurate data and an abundance of insects
to identify.
​
Within the groups of samples (undercut banks: tables 1&3, and snags: tables 2&4), not all
of our data matched. Specifically, Table 3’s data with only 14 organisms sampled differed
significantly from the rest of the groups (31, 40, and 94 organisms sampled). To analyze our
results, we decided to exclude Table 3’s data entirely from the overall quality assessment. This
leaves two snag samples and one undercut bank sample that all have >30 organisms. The
RiverWatch Stream Manual states that about 50 organisms should be collected in a sample.
(Illinois RiverWatch, 2021). Although Table 4 also doesn’t meet this requirement, we decided to
include it anyway because it’s very close. Taking the average of the two snag data sets, our
samples resulted in 63 organisms collected, 14 taxa richness, 5 EPT taxa richness, and 5.31 MBI.
The tentative quality rating from these averages equate to excellent, excellent, and fair,
respective to taxa richness, EPT taxa richness, and MBI. The sole undercut bank that was
examined equated to 40 organisms sampled, 14 taxa richness, 3 EPT taxa richness, and 5.4 MBI.
The tentative quality rating from this data equates to excellent, fair, and fair, respective to the
taxa richness, EPT taxa richness, and MBI.
​
As represented by the data of both the snag samples and the undercut bank sample, the
quality of the water at the time we sampled and at the location along the Sangamon River was at
least fair, and at most excellent. With 3 excellent and 3 fair ratings, it’s feasible that the ratings
can be set as good as an ‘average’ rating. Specific tables resembling each table’s sample
individually can be found below in the Appendix: Figures 4, 8, 12, and 16.
Conclusion
​
With the changes we made in data analysis (elimination of data analysis from table 3),
our stream health indices align with each other and show that the report sample location was in
good health at the time. With an average of 63 organisms collected, 14 taxa richness, 5 EPT taxa
richness, and 5.31 MBI from the snag samples and a total of 40 organisms sampled, 14 taxa
richness, 3 EPT taxa richness, and 5.4 MBI from the analyzed undercut bank sample. Reading
the data, a tentative quality rating of excellent, good, and fair can be assessed from these
readings, which generally results in a ‘Good’ rating for the overall river quality. If we were to
include the outlier data set, the overall river quality rating might have fallen into the ‘Poor’ rating
set due to the low number of organisms collected. (Illinois RiverWatch, 2021).
​
Aquatic insects are insects that spend at least a part of their life cycle in the water.
Aquatic insects are the main factor in assessing our river samples due to their sensitivity to
changes in their environment. Many aquatic insects live in the water as larvae, but some insects
live in freshwater for other parts, or all of their life. Lots of species are also born underwater and
then live their adult lives on land such as dragonflies and mayflies. We can find aquatic insects
within both holometabola and hemimetabola groups. Coleoptera, Trichoptera, and Diptera all fall
under the category of holometabolous, while Ephemeroptera, Plecoptera, and Odonata are all
hemimetabolous. (Michigan Technological University and the International Association of
Bryologists, 2021). The partitioning of niche and resources between life stages of these insects
allows nymphs and larvae to make use of past generations’ habitats and resources effectively.
Furthermore, these benefits give the insects in lower life stages a higher probability of surviving
and reduce predatory rates because of the environmental stability maintained throughout
different lifetimes of insects.
One adaptation that helps dragonfly larvae survive in streams is their masks for catching
prey. The mask is a modification of the labium, which includes the postmentum, prementum, and
labial palps (Ando 1962 in Biological Atlas of Aquatic Insects, 2002). The prementum is
attached to the rod-shaped basal segment called the postmentum (Biological Atlas of Aquatic
Insects, 2002). The labial palps differentiate the structural viability of the two main types of
masks: the pincer mask and the spoon mask are supported by the prementum (Biological Atlas of
Aquatic Insects. 2002). The teeth and bristle patterns in the prementum are often diagnostic
characteristics in some masks (Corbet 1963 in Biological Atlas of Aquatic Insects, 2002). These
mask parts make it a millisecond-speed grasping tool (Biological Atlas of Aquatic Insects, 2002).
A dragonfly larva’s extensor, flexor, and auxiliary muscles help swing the mask out (Biological
Atlas of Aquatic Insects, 2002). Then, the abductor and adductor muscles help open and close
the mask (Munscheid in Biological Atlas of Aquatic Insects, 2002). The mask is an important
adaptation for catching prey that helps dragonfly larvae survive in streams.
​ Organisms that live in a stable ecosystem are predictably unable to tolerate drastic
changes in temperatures and other environmental changes. Although this is true, four riffle beetle
species were examined and tested on for temperature change tolerance. The researchers
examined performance and survival of the beetles in response to increasing temperatures. They
used dynamic and static assays to test. Changes in metabolic rate were also tested for response to
thermal stress of each insect. The results concluded that the H. Comalensis is most sensitive
while the M. Pusillus is the least sensitive to thermal stress. The differences in climatic and
hydrological conditions in the geographical regions where the different riffle beetle populations
were determined their thermal sensitivity. All this addressed, the riffle beetles still all took the
change of temperature relatively well compared to some other insects that may have outputted
way higher stress levels during testing. This may be correlated to the riffle beetle elytra which
protects the beetle hind wings, but also possibly protects the beetle from temperature change.
(Journal of Thermal Biology, 2023).
​
There are countless threats that globally impact insect life in the world, including
pollution, habitat destruction, invasive species, and climate change. With these threats on the
rise, the Sangamon river specifically is subject to being impacted by at least one, if not all of
these threats, and therefore, their insect population will also subsequently be impacted and
decline substantially if nothing is done.
​
Recently greenhouse gasses have been on the rise. “The net result of increased plant
consumption and slower growth by herbivorous insects in elevated CO2 is likely to result in
increased exposure to natural enemies. For example, consumption of additional foliage increases
the probability of ingestion of viruses or pathogenic bacteria.” (Stilling, 2009). Of course
temperature change will affect everywhere, but especially freshwater environments due to
increased water temperatures. The Sangamon River is no different. Many freshwater insects are
highly sensitive to temperature, and elevated temperature can lead to accelerated metabolic rates
and shortened life spans of some insect species. Greenhouse gasses will change the oxygen
availability, and oxygen levels will reduce in warmer waters. Global warming could also start the
spread of invasive species of both plants and animals into this freshwater ecosystem. Some
species will compete with the Sangamon River insects for habitats or resources. Finally, rising
temperatures will also alter or result in the loss of habitats around the Sangamon River. Increased
CO2 levels will change the aquatic plant and algae growth rates, and insects that rely on these
plant materials may lose availability to their main source of food. As seen in Figure 18, the
Sangamon River is highly affected by global climate change, and this will result in a drastic
change and decline of the insects within this ecosystem.
​
It’s hard to make a change alone to a global issue like climate change. Some things the
world is doing currently is switching to renewable energy. Instead of focusing on using fossil
fuels and other sources of energy that release CO2, there has been a drastic recent shift to
renewable energy with solar power, wind power, and nuclear energy. Cars are being shifted to
electric-powered instead of using gas. Public transit is being invested in to reduce
single-passenger cars and enhance the quality of public transportation methods. Alternative fuels
are also being developed such as hydrogen, biofuels, and other low-carbon alternatives.
Agricultural practices are also transitioning to regenerative methods. No-till farming and crop
rotation can reduce the emission of greenhouse gasses from agriculture and enhance soil quality.
As an individual, you can reduce your carbon footprint by switching to renewable energy usage,
recycling properly, and carpooling/using public transportation or investing in an electric vehicle.
Although this world issue has a large impact on the Sangamon River and insects around the
world, it’s very hard to change the world completely on your own. Doing your part and
contributing as much as you can will still make a difference, and as the world transitions to more
sustainable sources of energy and a more environmentally friendly society, the environment
around us, including the Sangamon River, will return to a healthy environment for insects.
References
Introduction
National Park Service. (2022, July 14). Riparian Zones - It’s all about the Water. U.S.
Department of Interior.
https://www.nps.gov/articles/000/nrca_glca_2021_riparian.htm
Illinois RiverWatch. (2021). Illinois RiverWatch Stream Monitoring Manual. National Great
Rivers Research and Education Center, East Alton, IL
U.S. Environmental Protection Agency (2024, April 25). How’s My Waterway. U.S.
Environmental Protection Agency.
https://www.epa.gov/waterdata/hows-my-waterway
Conclusion
Illinois RiverWatch. (2021). Illinois RiverWatch Stream Monitoring Manual. National Great
Rivers Research and Education Center, East Alton, IL
Michigan Technological University and the International Association of Bryologists. (2021,
April 11). Aquatic Insects: Holometabola - Diptera, Suborder Brachycera. Michigan
Technological University Digital Commons.
https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?params=/context/bryo-ecol-subchapters/arti
cle/1115/&path_info=11_14Holometabola___Diptera__Suborder_Brachycera.pdf
Wichard, W., Arens, W., & Eisenbeis, G. (2002). The Biological Atlas of Aquatic Insects. Brill.
Nair, P., Gibson, J.R., Schwartz, B.F., & Nowlin, W.H. (2023). Temperature responses vary
between riffle beetles from contrasting aquatic environments. Journal of Thermal Biology, 112,
013485.
https://doi.org/10.1016/j.jtherbio.2023.103485
Stilling, P. (2009). Greenhouse Gases, Global Warming, and Insects. Encyclopedia of Insects,
112. University of South Florida, Tampa.
https://www.sciencedirect.com/science/article/abs/pii/B9780123741448001211
Appendix:
Figure 1: RiverWatch Site Sketch - Table 1
Figure 2: RiverWatch Habitat Survey Sheets - Table 1
Figure 3: RiverWatch Biological Survey Sheets - Table 1
Figure 4: RiverWatch Survey Data - Table 1
Figure 5: RiverWatch Site Sketch - Table 2
Figure 6: RiverWatch Habitat Survey Sheets - Table 2
Figure 7: RiverWatch Biological Survey Sheet - Table 2
Figure 8: RiverWatch Survey Data - Table 2
Figure 9: RiverWatch Site Sketch - Table 3
Figure 10: RiverWatch Habitat Survey Sheets - Table 3
Figure 11: RiverWatch Biological Survey Sheet - Table 3
Figure 12: RiverWatch Survey Data - Table 3
Figure 13: RiverWatch Site Sketch - Table 4
Figure 14: RiverWatch Habitat Survey Sheets - Table 4
Figure 15: RiverWatch Biological Survey Sheet - Table 4
Figure 16: RiverWatch Survey Data - Table 4
Figure 17: Watershed Map of Upper Sangamon River
Figure 18: Climate Change Threats Across the USA Chart