Aquatic Insect Populations of the Middle Provo River: Mitigation as Compared to Natural and Channel
Abstract
The Provo River in the Heber Valley is composed of naturally meandering sections, human channelized sections and human meandering sections. Historically the river was channelized which has led to some biological losses. After the construction of Jordanelle Reservoir sections of the stream were restored to their meandering state in an attempt to help restore the diversity and aquatic habitat that had been damaged from channelization. I collected aquatic insects from a channel site, a natural site and a restored site to determine the effect that mitigation and channelization had on aquatic insect populations. I determined that diversity was greatest in the channel, followed by the mitigation site and then by the naturally meandering site.
Keywords: macroinvertebrates, First 100, biodiversity
Introduction
The Provo River is a valuable waterway for a variety of reasons, including a major water source for the Wasatch Front with storage in the form of two large dams on either side of the Heber Valley (Bio-West 2004). During the mid-20th century the river in the Heber Valley was channelized to decrease evaporation and increase the efficiency of water transfer across the valley floor (Belk, pers. comm.). With the construction of the Jordanelle Reservoir came concerns of biologists about the negative effects of regulation of streams for biodiversity, which can have a negative effect on biological systems downstream (Dietrich, 1996). Funding was appropriated to restore the natural meandering of the river system. The Provo River Restoration
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Project (PRRP) was designed to “enhance biological productivity and diversity of aquatic habitat, riparian areas, and other environmental resources” (Bio-West 2009).
Various biological surveys have been taken in response to mitigation efforts such as those of Belk (2000), Ellsworth (2003) and Shiozawa (2002). Belk’s study of fish populations concluded that the mitigation efforts had been effective in increasing fish diversity as compared with the channelized locations (Belk, personal contact). Shiozawa (2003) studied macrobenthos populations. Macrobenthos are relatively large organisms that live at the bottom of a water column. He found that in general the channelized site generally contained lower biodiversity than the mitigated or natural sites, although this varied from year to year (Shiozawa, 2003 and Table 1). Ellsworth, like Belk, surveyed fish populations. He found that the naturally meandering site had the greatest species diversity followed by a mitigated study site and finally followed by the channelized site from which he extracted his samples (Ellsworth, 2003).
With the knowledge that the PRRP was designed to better aquatic habitat and diversity, I was interested in assessing the effects of mitigation on macroinvertebrate population diversity in the Heber Valley (Bio-West 2009). In many ways my study shadowed the structure used by Ellsworth in his 2003 study of Provo River fish populations.
The Heber Valley is flat-bottomed and therefore the Provo River which runs through it naturally was structured with meanders, not straight channels like those typical of constrained canyon streams (Gillum, 2006). Bio-West’s 2009 Final Environmental Impact report of 2006 notes that the river was channelized during the mid-1900s; subsequently efforts have been taken to undo the channelization in various sections of the river. I selected one of these restored sites, a channel site and a site in a 1.3 mile section of the river that wasn’t ever straightened. This study
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compares the macroinvertebrate populations in these sites to assess the effectiveness of mitigation on restoring biodiversity in aquatic insect populations.
Materials and Methods
Site Selection
Three sites were chosen for aquatic insect population sampling from the Provo River in the Heber Valley between Jordanelle Reservoir and Deer Creek Reservoir (Table 2). The Provo River in the Heber Valley was historically channelized to increase efficiency in water transfer from an engineering perspective. A natural river meanders, when traveling across a flat valley, making large loops which from an engineering point of view is inefficient because it increases the time of water transfer and is prone to flooding (Gillum, 2006). When the Jordenalle Dam was constructed a compromise had to be reached between environmental interests and the dam advocates. The Utah Reclamation Mitigation and Conservation Commission received funding to restore the meanders and natural environment of the river in the Heber Valley (Bio-West, 2009).
Channeling rivers decreases time of water transfer and probability of flooding (Gillum, 2006); however, there are serious biological losses in the channelization of a river system such as the loss of habitat area, increased velocities resulting in elimination of species adapted to lower velocities, and general decrease in aquatic fish and macroinvertebrate populations (Brooker, 1985). Mitigation attempts to restore the biological health that is damaged in channelization (Bio-West, 2009). I was interested in comparing the aquatic insect populations in areas that were channelized and then mitigated, currently channelized, and naturally meandering.
The first site chosen was located in a mitigated area slightly downstream from Jordanelle Reservoir (Table 2 and Figure 1). This site was chosen as a representation for aquatic insect populations in mitigated areas of the Provo River.
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The second site was chosen in an area that was never channelized and had retained the natural meanders of the river (Table 2 and Figure 1). This site was chosen to examine the effects of channelization and mitigation as compared to the natural stream (Figure 2).
The third site was chosen from an area that was channelized (Table 2, Figure 1 and Figure 2).
Sampling
I used an aquatic insect net to collect samples from the stream. The net was approximately 30 cm x 15 cm and had solid fabric on the sides from the opening until the bottom. The bottom was constructed from extremely fine mesh so that water could go through but small insects like midges could be caught. My net motions included running the net through submerged vegetation, setting the net downstream while disturbing vegetation, setting the net downstream while I disturbed the bed of the stream (rocks, silt, sand) and finally simply sweeping through the stream flow. The insects collected were deposited in a white tray, partially filled with water, from which they were placed in test tubes filled with 70% ethanol using forceps. 110 invertebrates were collected from each site in this manner.
This type of sample is known as a “First 100 Sample.” It is important to emphasize the “first” because no special effort was taken to maximize the diversity of specimens collected while sampling. Rather I attempted to quantitatively match the proportions of insects collected from the stream. Ten extra insects were sampled to insure that at least 100 invertebrates were sampled from each site, with the knowledge that counting errors can and do occur, whether from undercounting, incorrect identification of what is an insect and what is plant mass, or losing the organism while attempting to transfer it from the tray to the vial.
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After samples from the three Heber Valley sites were collected macroinvertebrates were taken to the lab of Dr. Nelson of the Brigham Young University Biology Department. Specimens were identified to the family with aid from computer identification software (Nelson, 2006), a field guide book (Borror, 1970), and help from Dr. Nelson. Specimens were examined under a stereo dissecting microscope (Olympus SZX-ILLB100) and some were photographed on a microscope (Olympus SZX-ILLB100 with Olympus DP111 camera) as well.
The results were then organized graphically using Microsoft Excel for visual representation of data.
Results
After sampling and lab identification I reached these results. Of the three sites the channel site had the greatest biodiversity, as far as number of families collected. I collected specimens from 11 different families: Trichoptera brachycentridae, Chironomidae (midges), Elmidae Elmina Optioservus, Ephemeroptera Ephemerellidae, Perlodidae Isoperla, Trichoptera limnephilidae, Dytiscidae, Asellidae Asellus aquaticus, Coleoptera Elmidae Baetidae, Hydropsychidae hydropsyche, Ephemerellidae Drunella grandis (Table 3 and Figure 4). Chironomidae dominated the sample numerically, composing 28% of the specimens collected in the sample (Table 3).
The mitigation site sample contained 7 families: Chironomidae, Trichoptera hesperophylax, Trichoptera brachycentridae, Hydropsychidae hydropsyche, Ephemerellidae Drunella grandis, Perlodidae Isoperla, Ephemeroptera Ephemerellidae. The most common family numerically was the Trichoptera brachycentridae, which was 41% of the sample (Table 3 and Figure 4).
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The site with the fewest number of families collected was the site taken from the 1.3 miles that were never channelized and had retained their natural meanders. Six families were collected at this site: Asellidae Asellus aquaticus, Ephemeroptera Ephemerellidae, Chironomidae, Trichoptera brachycentridae, Physidae Physella, Perlodidae Isoperla. Ephemeroptera Ephemerellidae is the most common numerically, 39% of the sample (Table 3 and Figure 4).
Discussion
Mitigation efforts were undertaken to attempt to revitalize diversity and ecosystem health. My results run contrary to the studies of the Provo River commissioned by the mitigation committee (Bio-West 2009 and 2004) and Ellsworth (2003). Dr. Belk is a fish specialist. In his survey of the Provo River in 2000 in the Heber Valley he discovered that areas that were mitigated contained greater fish diversity than channelized locations (Belk, pers. comm.). A similar study was conducted in 2003 by Ellsworth that shared similar results regarding greater fish biodiversity in mitigated and natural sites when compared to channel sites (Ellsworth, 2003). Fish subsist on insect populations; therefore it follows that insect populations should correlate with fish populations (Belk, Personal Contact). My study results run contrary to Belk’s judgment that insect population diversity should correlate with fish populations. My sampling also ran contrary to the study conducted by Shiozawa of Macrobenthos (Shiozawa, 2002). There are several reasons why this seeming discrepancy between other studies and my study may have occurred. One explanation would be human impacts, urbanization, agriculture, or land development to name a few (Bilby et al., 2003). For example both the mitigation site and the natural site are very close to fairly busy automobile highways. A study could be conducted to test the effect of a nearby highway on insect populations. One other explanation is that insect
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diversity is actually better in channelized sections and the reason that fish populations seem to counter this may be due to other factors like the gross number of insects present, biomass of insects in a stream section, or some other factor. I suspect that other factors like biomass and insect concentrations would provide a better insight into the effectiveness of mitigation efforts, because I noticed that sampling at the channel site took more sweeps and time in order to obtain first 100 samples. An interesting study to further understand the effects of mitigation and channelization on insect populations would be a study assessing the concentration of insects and/or the biomass of insect population samples in different stream locations


Literature Cited
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Belk, Mark C. Personal Contact. Brigham Young University Biology Department.
Bilby et al, 2003. Sources of Variability in Aquatic Ecosystems: Factors Controlling Biotic Production and Diversity. Strategies for restoring River Ecosystems: Sources of Variability and Uncertainty in Natural and Managed Systems. Editors: Bisson and Wissmer. 2003.
Bio-West Inc., 2004. Oborny E., Olsen D., Stamp M.; Addley C, Watershed Systems Group. Provo River Flow Study 2004. Submitted to Mark Holden, Utah Reclamation Mitigation and Conservation Commission 1063 West 1400 North
102 West 500 South, Suite 315, Salt Lake City, Utah 84101.
Bio-West Inc., 2009. Olsen D. Middle Provo Monitoring Report, 2006. Submitted to Mark Holden, Utah Reclamation Mitigation and Conservation Commission,
230 South 500 East Suite 230, Salt Lake City, Utah 84102
Borror and White, 1970. Peterson Field Guides: Insects. Houghton and Mifflin Publishing Company.
Brooker, M.P., 1985. The Ecological Effects of Channelization. The Geographical Journal Vol. 151, No. 1 pp. 63-66. Blackwell Publishing Co.
Dietrich et al 1996. Dams and Downstream Aquatic Biodiversity: Potential Food web consequences of hydrologic and geomorphic change. Environmental Management Volume 20, Number 6 (1996).
Ellsworth, C.M. 2003. Response of the fish Community and Age Class Structure to Channelization and Habitat Restoration in the Provo River Between Deer Creek and Jordanelle reservoirs. Thesis submitted to the faculty at Brigham Young University, Department of Integrative Biology.
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Gilluum and Stafford, 2006. Stream Channelization in the Saratoga Lake Watershed. Senior Capstone Project in Enviornmental Studies. Environmental Studies Program Skidmore College. Advisors: Kellog and McMillan.
Nelson, C. R. 2006. Freshwater Aquatic Invertebrate Identification Guide: electronic keys to explore the diversity of animals in the freshwaters of western North America. Center for Instructional Design, Brigham Young University (BYU), Provo Utah, USA. CD software, BYU Creative works. http://creativeworks.byu.edu/catalog/ViewItem.aspx?item=IB002
Shiozawa D.K., B.J. Weibell, and E. McLaughlin. 2002. The investigation of the macrobenthos of the Provo River between Jordanelle and Deer Creek Reservoirs: A report to the Utah Reclamation Mitigation and Conservation Commission. Brigham Young University, Provo, UT. 45 p.

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