Long Term Resource Monitoring Program

Program Report

99-P001

Mayflies (Ephemeroptera) and

Fingernail Clams (Sphaeriidae)

at Selected Sites

in the Upper Mississippi River System

 February 1999
The Upper Midwest Environmental Sciences Center issues LTRMP Program Reports

to provide Long Term Resource Monitoring Program partners

with programmatic documentation, procedures manuals, and annual status reports.

Upper Midwest Environmental

Sciences Center

PROGRAM MANAGER

Robert L. Delaney

ACTING MONITORING SCIENCES

AND COORDINATION MANAGER

Kenneth S. Lubinski

ACTING SUPPORT SERVICES

DIVISION MANAGER

Barbara A. Deml

REPORT EDITOR

Deborah K. Harris

Cover graphic by Mi Ae Lipe-Butterbrodt

Mention of trade names or commercial products does not constitute endorsement

or recommendation for use by the U.S. Department of the Interior, U.S. Geological Survey.
Mayflies (Ephemeroptera) and

Fingernail Clams (Sphaeriidae)

at Selected Sites

in the Upper Mississippi River System

by

Jennifer S. Sauer

February 1999

U.S. Geological Survey

Upper Midwest Environmental Sciences Center

2630 Fanta Reed Road

La Crosse, Wisconsin 54603
Suggested citation:

Sauer, J. 1999. Mayflies (Ephemeroptera) and fingernail clams (Sphaeriidae) at selected sites in the Upper Mississippi River

System. U.S. Geological Survey, Upper Midwest Environmental Sciences Center, La Crosse, Wisconsin, February 1999.

LTRMP 99-P001. 19 pp. + Appendix 

Additional copies of this report may be obtained from the National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161 (1-800-553-6847 or 703-487-4650). Also available to registered users from the Defense Technical

Information Center, Attn: Help Desk, 8725 Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or

703-767-9050).
ii

 Contents

Page

Preface ......................................................................... v

Abstract ......................................................................... 1

Introduction ...................................................................... 1

Methods ........................................................................ 1

Results ......................................................................... 3

Pool 4 ....................................................................... 3

Pool 8 ....................................................................... 3

Pool 13 ..................................................................... 10

Pool 26 ..................................................................... 10

Open River .................................................................. 10

La Grange Pool ............................................................... 10

Summary ....................................................................... 17

Acknowledgments ................................................................ 17

References ...................................................................... 17

Appendix. Sampling Sites ......................................................... A-1

Tables

Table 1. Macroinvertebrate sampling methods by various researchers at selected sites in the

Upper Mississippi River System ............................................. 4

Table 2. Number of macroinvertebrate sample sites by study area and year .................... 5

Table 3. Sampling dates for macroinvertebrate sampling .................................. 6

Figures

Figure 1. Long Term Resource Monitoring Program study areas for macroinvertebrate sampling ... 2

Figure 2. Abundance of mayflies (Ephemeroptera) at sites 501–504 in Pool 4 of the Upper Mississippi

River System .......................................................... 7

Figure 3. Abundance of fingernail clams (Sphaeriidae) at sites 501–504 in Pool 4 of the Upper

Mississippi River System ................................................. 7
iii

Figure 4. Abundance of mayflies (Ephemeroptera) at sites 501–508 in Pool 8 of the Upper Mississippi

River System .......................................................... 8

Figure 5. Abundance of mayflies (Ephemeroptera) at sites 509–516 in Pool 8 of the Upper Mississippi

River System .......................................................... 8

Figure 6. Abundance of fingernail clams (Sphaeriidae) at sites 501–508 in Pool 8 of the Upper

Mississippi River System ................................................. 9

Figure 7. Abundance of fingernail clams (Sphaeriidae) at sites 509–516 in Pool 8 of the Upper

Mississippi River System ................................................. 9

Figure 8. Abundance of mayflies (Ephemeroptera) at sites 501–507 in Pool 13 of the Upper

Mississippi River System ................................................ 11

Figure 9. Abundance of fingernail clams (Sphaeriidae) at sites 501–507 in Pool 13 of the Upper

Mississippi River System ................................................ 11

Figure 10. Abundance of mayflies (Ephemeroptera) at sites 501–507 in Pool 26 of the Upper

Mississippi River System ................................................ 12

Figure 11. Abundance of fingernail clams (Sphaeriidae) at sites 501–507 in Pool 26 of the Upper

Mississippi River System ................................................ 12

Figure 12. Abundance of mayflies (Ephemeroptera) at sites 501–509 in the Open River reach of

the Upper Mississippi River System ........................................ 13

Figure 13. Abundance of mayflies (Ephemeroptera) at sites 510–518 in the Open River reach of

the Upper Mississippi River System ........................................ 13

Figure 14. Abundance of fingernail clams (Sphaeriidae) at sites 501–509 in the Open River reach of the

Upper Mississippi River System ........................................... 14

Figure 15. Abundance of fingernail clams (Sphaeriidae) at sites 510–518 in the Open River reach of the

Upper Mississippi River System ........................................... 14

Figure 16. Abundance of mayflies (Ephemeroptera) at sites in Lake Matanzas (LM) and Quiver Lake

(QL) in La Grange Pool of the Illinois River .................................. 15

Figure 17. Abundance of mayflies (Ephemeroptera) at sites 523–526 in La Grange Pool of the

Illinois River ......................................................... 15

Figure 18. Abundance of fingernail clams (Sphaeriidae) at sites in Lake Matanzas (LM) and

Quiver Lake (QL) in La Grange Pool of the Illinois River ........................ 16

Figure 19. Abundance of fingernail clams (Sphaeriidae) at sites 523–526 in La Grange Pool of the

Illinois River ......................................................... 16
v

Preface

The Long Term Resource Monitoring Program (LTRMP) was authorized under the Water

Resources Development Act of 1986 (Public Law 99-662) as an element of the U.S. Army

Corps of Engineers’ Environmental Management Program. The LTRMP is being implemented

by the Upper Midwest Environmental Sciences Center (formerly Environmental Management

Technical Center), a U.S. Geological Survey science center, in cooperation with the five

Upper Mississippi River System (UMRS) States of Illinois, Iowa, Minnesota, Missouri, and

Wisconsin. The U.S. Army Corps of Engineers provides guidance and has overall Program

responsibility. The mode of operation and respective roles of the agencies are outlined in a

1988 Memorandum of Agreement.

The UMRS encompasses the commercially navigable reaches of the Upper Mississippi

River, as well as the Illinois River and navigable portions of the Kaskaskia, Black, St. Croix,

and Minnesota Rivers. Congress has declared the UMRS to be both a nationally significant

ecosystem and a nationally significant commercial navigation system. The mission of the

LTRMP is to provide decision makers with information for maintaining the UMRS as a

sustainable large river ecosystem given its multiple-use character. The long-term goals of the

Program are to understand the system, determine resource trends and effects, develop

management alternatives, manage information, and develop useful products.

This report supports Task 2.2.7.4, Evaluate and Summarize Annual Results, as specified

in Goal 2 of the LTRMP Operating Plan (U.S. Fish and Wildlife Service 1993). This report

was developed with funding provided by the Long Term Resource Monitoring Program.
Mayflies (Ephemeroptera) and

Fingernail Clams (Sphaeriidae)

 at Selected Sites

in the Upper Mississippi River System

by

Jennifer S. Sauer

Abstract

As part of the Long Term Resource Monitoring Program (LTRMP) macroinvertebrate component, historical

sites (sites where benthic samples were previously collected by other researchers) were sampled in 1992

through 1998. Historical data on densities of the taxa were obtained from published literature and compared

to data collected by the LTRMP. Temporal trends and spatial distribution in the abundance of mayflies

(Ephemeroptera) and fingernail clams (Sphaeriidae) were examined in Navigation Pools 4, 8, 13, 26, and the

Open River reach of the Mississippi River and La Grange Pool of the Illinois River. 

Introduction

Macroinvertebrate sampling on the Upper Mississippi River System (UMRS) has a rich history. Records

of sampling date back to the 1800s (Hart 1895). Mayflies and fingernail clams are important components of

the aquatic food web—Thompson (1973) found that in fall, lesser scaup (Aythya affinis) gizzards contained

76% sphaeriids and about 13% mayflies. Thompson also found both organisms important to canvasbacks

(A. valisneria), ring-necked ducks (A. collaris), and American coots (Fulica americana) feeding in open water.

Many commercial and recreational fish utilize both organisms (Hoopes 1960; Jude 1968; Ranthum 1969).

Mayflies and fingernail clams have also traditionally been used as biological indicators of river water quality

(Fremling 1964, 1973, 1989; Rosenberg and Resh 1993; Steingraber and Weiner 1995). Macroinvertebrates

also perform an important ecological function by digesting organic material and recycling nutrients (Reice and

Wohlenberg 1992). 

The objective of this report is to document long-term patterns in mayfly and fingernail clam abundance from

selected sites within the UMRS. 

Methods

In 1992, macroinvertebrate sampling was initiated in six study areas on the UMRS. The six Long Term

Resource Monitoring Program (LTRMP) study areas represent the variety of aquatic areas within the UMRS.

They range in size (calculated from Geographic Information System coverages; Lowenberg 1993) from Pool 8

(19,000 ha) to the Open River (107,000 ha). Study areas of the LTRMP are referred to herein according to

the navigation pool designations of the U.S. Army Corps of Engineers lock and dam system: Pools 4

(Mississippi River mile 752 to 797), 8 (679 to 703), 13 (523 to 557), 26 (202 to 242), and the Open River

reach (29 to 80) of the Mississippi River; and La Grange Pool (Illinois River mile 80 to 158) of the Illinois

River (Figure 1). 
Pool 4

Pool 8

Pool 13

La Grange Pool

Pool 26

Open River

2

Figure 1. Long Term Resource Monitoring Program study areas for macroinvertebrate sampling.

In addition to the stratified random sampling of the LTRMP macroinvertebrate component (Thiel and Sauer

1995), part of the sampling scheme included historical sites, that is, sites where benthic samples were

previously collected by other researchers (Paloumpis and Starrett 1960; North Star Research Institute 1973;
3

Emge et al. 1974; Colbert et al. 1975; Anderson 1977; Elstad 1977; Hubert et al. 1983; Brewer 1992;

Appendix). The present report describes data from samples taken at the historical sites.

Macroinvertebrate sampling procedures are described in detail in the LTRMP Procedures Manual

(Thiel and Sauer 1995). Benthic samples were collected with a winch-mounted 0.052-m standard Ponar grab 2

sampler (Ponar Grab Dredge, Wildlife Supply Company, Saginaw, Michigan). To increase sorting efficiency

in the field, the wash frame sieve size was changed from a U.S. Standard Sieve No. 30 (595 Fm), used in 1992,

to a U.S. Standard Sieve No. 16 (1.18 mm) in 1993. Thus, inferences in macroinvertebrate numbers made from

these data are restricted to the larger organisms of the population (Dukerschein et al. 1996). Mayflies

(Ephemeroptera), fingernail clams (Sphaeriidae), midges (Chironomidae), Asiatic clams (Corbicula sp.), and

zebra mussels (Dreissena polymorpha) were picked and counted in the field. The present report describes only

mayfly and fingernail clam data. Density was recorded for each target taxa from individual Ponar samples.

Whenever a taxon was not caught in a sample, the catch for that taxon in that sample was recorded as zero.

Researchers have used a variety of methods to sample macroinvertebrates (Table 1). For comparison,

abundance data were converted to individuals per square meter. Abundance data were not statistically analyzed

for differences between years because of the small sample size (Table 2). Table 3 lists the sampling period for

each year.

Results

Pool 4

The highest number of mayflies and fingernail clams reported by North Star Research Institute (1973) were

at sample sites 502 and 503 in Pool 4 (Figures 2 and 3), where he reported 105.8 m mayflies and 86.5 m 2 2

fingernail clams. Between 1992 and 1998, the highest densities of mayflies and fingernail clams were 576.9

m (site 504; backwater contiguous [BWC]) and 230.8 m (site 501; tributary delta lake [TDL]), respectively. -2 -2

Over the years, the general distribution of mayflies was highest at sample site 504—BWC aquatic area; mayfly

densities have been increasing at this site. Fingernail clam distribution was highest at the TDL aquatic area.

Pool 8

The highest number of mayflies and fingernail clams reported by Elstad (1977) at sample sites in Pool 8

(Figures 4–7), corresponding to LTRMP sites, was 1,353.5 m and 5,184.9 m , respectively. At most sample -2 -2

sites, the abundances of mayflies and fingernail clams have never rebounded to the numbers seen by Elstad in

the 1970s. Brewer (1992) noted significant declines in total macroinvertebrate abundance in open water

habitats and no significant changes in marsh, channel, and dredge areas. The highest density of mayflies found

by Brewer was 241.3 m , and the highest density of fingernail clams was 243.5 m . Between 1992 and 1998, -2 -2

the highest densities of mayflies and fingernail clams were 1,038.5 m and 365.4 m , respectively. Over the -2 -2

years, the general distribution of mayflies was highest at sample sites 502, 504–506, 510, and 514—BWC and

impounded area (IMP) aquatic areas. Fingernail clam distribution was highest at the IMP aquatic area. The

IMP aquatic areas seem to have more favorable habitat for fingernail clams; that is, areas that are less stagnant

and generally have more flow than the BWC aquatic areas. 
4

Table 1. Macroinvertebrate sampling methods by various researchers at selected sites in the Upper Mississippi River

System.

Pool 4 - North Star Research Institute 1973 Pool 26 - Colbert et al. 1975

C 2 Ponar grabs collected and contents pooled C 2 Peterson or Ponar grabs 

C No. 40 soil sieve size (425 Fm) C No. 30 sieve size (595 Fm)

C Purpose of the transects was to provide comparative C 4 habitat types sampled (main channel, side channel, main

sampling locations within and between pools channel border, main channel border influenced by dikes);

C Sampling period spring and summer 1973 transects run

C 4 sites resampled for the Long Term Resource Monitoring C Sampling period 2–12 July 1974

Program (LTRMP) C 6 sites resampled for the LTRMP

Pool 8 - Elstad 1977

C 1 dredge haul (0.023 m )

2

C No. 30 sieve size (595 Fm)

C 41 sampling areas chosen, 2 main channel areas and

39 adjacent waters; transects run east–west

C Sampling period 15 June to 15 July 1975

C 16 sites resampled for the LTRMP

Pool 8 - Brewer 1992

C 2 Petite Ponar dredge hauls combined (0.046 m )

2

C No. 30 sieve size (595 Fm)

C Resampled Elstad’s sites

C Sampling period 21 June to 13 July 1990

C 16 sites resampled for the LTRMP

Pool 13 - Hubert 1983

C 1 Peterson dredge (0.092 m ); 3 replicates at each site

2

pooled

C Sieve (0.5 mm)

C 6 habitat types chosen for sampling (main channel, main

channel border, tail water, side channel, lakes, and sloughs)

C Sampling period 26 February to 6 March 1983

C 7 sites resampled for the LTRMP

Pool 26 - Seagle and Zumwalt 1981

C 1 Ponar grab (0.052 m )

2

C No. 30 sieve size (595 Fm)

C Above wing dam

C Sampling period April 1981

C 1 site resampled for the LTRMP

Open River - Emge et al. 1974

C 2 Peterson dredge hauls collected and contents pooled

(0.16 m )

2

C No. 30 sieve size (595 Fm)

C Side channels and main channel border sampled

C Sampling period late June 1972 or July 1973

C 18 sites resampled for the LTRMP

La Grange Pool - Paloumpis and Starrett 1960

C Ekman dredge 6 × 6 inches

C No. 30 sieve size (595 Fm)

C Lake Matanzas and Quiver Lake; 1952–54

C 22 sites resampled for the LTRMP

La Grange Pool - Anderson 1977

C Ekman dredge 6 × 6 inches

C No. 30 sieve size (595 Fm)

C August through September 1975

C 4 sites resampled for the LTRMP
5

Table 2. Number of macroinvertebrate sample sites by study

area and year.

Study area Number of historical

and year sites sampled

Pool 4

1973 4

1992 4 

1993 4 

1994 4 

1995 4 

1996 4 

1997 4 

1998 4 

Pool 8

1975 16

1990 16 

1992 16 

1993 16 

1994 16 

1995 16 

1996 16 

1997 16 

1998 16 

Pool 13

1983 7

1992 7 

1993 7 

1994 7 

1995 7 

1996 7 

1997 7 

1998 7 

Pool 26

1974 7

1981 1

1992 7 

1993 3

1994 7 

1995 0

1996 7 

1997 0

1998 7 

Open River

1973 18

1992 4

1993 0

1994 15

1995 9

1996 18 

1997 0

1998 18 

La Grange Pool

1952–53 22

1975 4

1992 23 

1993 26 

1994 25 

1995 26 

1996 26 

1997 26 

1998 26 

a

a

a

a

a

b

b

b

a

b

b

b

b

b

a

a

Number of sites chosen from research project for Long Term a

 Resource Monitoring Program macroinvertebrate sampling.

Sample sites low because of flooding. b
6

Table 3. Sampling dates for macroinvertebrate sampling.

Study area and year Sampling period

Pool 4

1973 Spring and summer

1992 June 13–30

1993 May 3–14

1994 May 2–10

1995 May 3–11

1996 May 9–15

1997 May 8–13 

1998 May 4–13

Pool 8

1975 June 15–July 15

1991 June 21–July 13

1992 June 15–26

1993 May 24–June 10

1994 May 23–June 6

1995 May 22–June 2

1996 May 20–29

1997 May 27–June 2

1998 April 30–May 11

Pool 13

1983 February 26–March 6

1992 June 2–23

1993 April 12–June 1

1994 May 10–June 1

1995 May 11–19

1996 May 31–June 6

1997 May 19–23

1998 May 11–20

Pool 26

1974 July 2–12

1981 April

1992 June 2–26

1993 April 12–June 10

1994 May 10–31

1995 May 11–19

1996 May 9–15

1997 —

1998 May 18–27

Open River

1972–73 June 1972 or July 1973

1992 June 1–12

1993 —

1994 April 4–12

1995 April 3–17

1996 March 27–April 5

1997 —

1998 May 26–June 3

La Grange Pool

1952–53 Spring and summer

1975 August–September

1992 June 8–24

1993 April 28–May 12

1994 May 2–12

1995 May 1–10

1996 May 6–15

1997 April 29–May 8

1998 May 4–18

a

Not sampled because of flooding. a
501 502 503 504

Sample Site Number

0

100

200

300

400

500

600

700

Number per square meter

1973

1993

1994

1995

1996

1997

1998

1992

501 502 503 504

Sample Site Number

0

50

100

150

200

250

Number per square meter

1973

1993

1994

1995

1996

1997

1998

1992

7

Figure 2. Abundance of mayflies (Ephemeroptera) at sites 501–504 in Pool 4 of the Upper

Mississippi River System.

Figure 3. Abundance of fingernail clams (Sphaeriidae) at sites 501–504 in Pool 4 of the Upper

Mississippi River System.
501 502 503 504 505 506 507 508

Sample Site Number

0

200

400

600

800

1000

1200

1400

Number per square meter

1992

1990

1975

1993

1994

1995

1996

1997

1998

509 510 511 512 513 514 515 516

Sample Site Number

0

200

400

600

800

1000

1200

Number per square meter

1992

1990

1975

1993

1994

1995

1996

1997

1998

8

Figure 4. Abundance of mayflies (Ephemeroptera) at sites 501–508 in Pool 8 of the Upper

Mississippi River System.

Figure 5. Abundance of mayflies (Ephemeroptera) at sites 509–516 in Pool 8 of the Upper

Mississippi River System.
501 502 503 504 505 506 507 508

Sample Site Number

1

10

100

1000

10000

Log Scale

1992

1990

1975

1993

1994

1995

1996

1997

1998

509 510 511 512 513 514 515 516

Sample Site Number

1

10

100

1000

10000

Log Scale

1992

1990

1975

1993

1994

1995

1996

1997

1998

9

Figure 6. Abundance of fingernail clams (Sphaeriidae) at sites 501–508 in Pool 8 of the Upper

Mississippi River System.

Figure 7. Abundance of fingernail clams (Sphaeriidae) at sites 509–516 in Pool 8 of the Upper

Mississippi River System.
10

Pool 13

The highest number of mayflies and fingernail clams reported by Hubert et al. (1983) at sample sites in

Pool 13 (Figures 8 and 9) from the present study was 1,017.4 m (site 502; side channel area [SC]) and

-2

1,544.6 m (site 507; IMP), respectively. Between 1992 and 1998, the highest densities of mayflies and

-2

fingernail clams were 1,615.4 m and 1,211.5 m (site 503; SC), respectively. Over the years, the general

-2 -2

distribution of mayflies was highest at sample sites 502–504—SC aquatic areas. Fingernail clam distribution

was greatest in the IMP and SC aquatic areas. 

In 1983, Hubert et al. found that lake habitats (N = 18) supported a mean of 66 m Hexagenia and 295 m -2 -2

Sphaerium. In three of the lake sites resampled by the LTRMP, mean densities of mayflies ranged from 121.8

to 528.5 m and mean densities of fingernail clams ranged from 102.6 to 1,051.3 m .

-2 -2

Pool 26

The highest number of mayflies and fingernail clams reported by Colbert et al. (1975) at sample sites in

Pool 26 (Figures 10 and 11) from the present study was 172.0 m (site 503; SC) and 25.0 m (site 501; main -2 -2

channel border [MCB]), respectively. Between 1992 and 1998, the highest densities of mayflies and fingernail

clams were 1,038.5 m (site 503; SC) and 57.7 m (site 507; SC), respectively. The general distribution of -2 -2

mayflies was highest at sample site 504, an SC aquatic area. Seagle et al. (1982) reported a Hexagenia density

as high as 454 m (N = 9; 5 replicates at each site). Of 37 samples taken over the years (1992–98), only 1

-2

contained fingernail clams. 

Open River

The highest number of mayflies reported by Emge et al. (1974) at sample sites in the Open River reach

(Figures 12–15) from the present study was 675.0 m (site 518; MCB). Between 1992 and 1998, the highest -2

densities of mayflies was 384.6 m (site 515; SC). Over the years, the general distribution of mayflies was

-2

highest at sample sites 515 and 518—SC and MCB aquatic areas, respectively. No sites contained fingernail

clams.

La Grange Pool

The highest number of mayflies and fingernail clams reported by Anderson (1977) at sample sites 523–526

in La Grange Pool (Figures 16–19) was 34.4 m (site 523; SC) and 34.4 m (site 524; SC), respectively.

-2 -2

Between 1992 and 1997, the highest densities of mayflies and fingernail clams were 173.0 m (site 512; Quiver -2

Lake) and 192.3 m (site 523; SC), respectively. Over the years, the general distribution of mayflies was

-2

highest at sample sites in Quiver Lake. Fingernail clam distribution was also highest at the Quiver Lake area

with a mean maximum of 17,201.9 m in 1952, as reported by Paloumpis and Starrett (1960). -2

Richardson (1921) took benthic samples at Lake Matanzas in 1915 and found no Hexagenia mayfly

nymphs and 225.7 m fingernail clams in samples with depths between 6.5 and 8.5 feet and no vegetation, and -2

5.5 m Hexagenia and 52.9 m fingernail clams in samples with depths of 2 to 6 feet and some vegetation at -2 -2

all sites. Richardson also took samples in middle Quiver Lake and found Hexagenia densities less than 0.5 m-2

in 1914 and 1915 and fingernail clam densities of 42.0 m in 1914 and 0.8 m in 1915. -2 -2
501 502 503 504 505 506 507

Sample Site Number

0

200

400

600

800

1000

1200

1400

1600

Number per square meter

1992

1983

1993

1994

1995

1996

1997

1998

501 502 503 504 505 506 507

Sample Site Number

0

200

400

600

800

1000

1200

1400

1600

Number per square meter

1992

1983

1993

1994

1995

1996

1997

1998

11

Figure 8. Abundance of mayflies (Ephemeroptera) at sites 501–507 in Pool 13 of the Upper

Mississippi River System.

Figure 9. Abundance of fingernail clams (Sphaeriidae) at sites 501–507 in Pool 13 of the Upper

Mississippi River System.
501 502 503 504 505 506 507

Sample Site Number

0

200

400

600

800

1000

1200

Number per square meter

1992

1974

1993

1994

1995

1996

1997

1998

501 502 503 504 505 506 507

Sample Site Number

0

10

20

30

40

50

60

Number per square meter

1992

1974

1993

1994

1995

1996

1997

1998

12

Figure 10. Abundance of mayflies (Ephemeroptera) at sites 501–507 in Pool 26 of the Upper

Mississippi River System.

Figure 11. Abundance of fingernail clams (Sphaeriidae) at sites 501–507 in Pool 26 of the

Upper Mississippi River System.
501 502 503 504 505 506 507 508 509

Sample Site Number

0

20

40

60

80

100

120

140

Number per square meter

1992

1973

1993

1994

1995

1996

1997

1998

510 511 512 513 514 515 516 517 518

Sample Site Number

0

100

200

300

400

500

600

700

Number per square meter

1992

1973

1993

1994

1995

1996

1997

1998

13

Figure 12. Abundance of mayflies (Ephemeroptera) at sites 501–509 in the Open River reach of

the Upper Mississippi River System. Sites were not sampled in 1993 or 1997 because of flooding.

Figure 13. Abundance of mayflies (Ephemeroptera) at sites 510–518 in the Open River reach of

the Upper Mississippi River System. Sites were not sampled in 1993 or 1997 because of flooding.
501 502 503 504 505 506 507 508 509

Sample Site Number

0

2

4

6

8

10

Number per square meter

1992

1973

1993

1994

1995

1996

1997

1998

510 511 512 513 514 515 516 517 518

Sample Site Number

0

2

4

6

8

10

Number per square meter

1992

1973

1993

1994

1995

1996

1997

1998

14

Figure 14. Abundance of fingernail clams (Sphaeriidae) at sites 501–509 in the Open River

reach of the Upper Mississippi River System. Sites were not sampled in 1993 or 1997 because of

flooding.

Figure 15. Abundance of fingernail clams (Sphaeriidae) at sites 510–518 in the Open River

reach of the Upper Mississippi River System. Sites were not sampled in 1993 or 1997 because of

flooding.
LM QL

Sample Site Number

0

10

20

30

40

50

Number per square meter

1952

1992

1953

1993

1994

1995

1996

1997

1998

523 524 525 526

Sample Site Number

0

10

20

30

40

50

Number per square meter

1992

1975

1993

1994

1995

1996

1997

1998

15

Figure 16. Abundance of mayflies (Ephemeroptera) at sites in Lake Matanzas (LM) and

Quiver Lake (QL) in La Grange Pool of the Illinois River.

Figure 17. Abundance of mayflies (Ephemeroptera) at sites 523–526 in La Grange Pool of the

Illinois River.
LM QL

Sample Site Number

1

10

100

1000

10000

100000

Log Scale

1952

1992

1953

1993

1994

1995

1996

1997

1998

523 524 525 526

Sample Site Number

0

50

100

150

200

Number per square meter

1992

1975

1993

1994

1995

1996

1997

1998

16

Figure 18. Abundance of fingernail clams (Sphaeriidae) at sites in Lake Matanzas (LM) and

Quiver Lake (QL) in La Grange Pool of the Illinois River.

Figure 19. Abundance of fingernail clams (Sphaeriidae) at sites 523–526 in La Grange Pool of the

Illinois River.
17

Summary

Even though we have limited historical data, these data combined with the LTRMP data can help us get

an idea of the variation of mayfly and fingernail clam densities over the long term. Not surprisingly, yearly

changes in organism abundance were noted at all sites in the study areas. Historically, Pools 8 and 13 had the

highest density of mayflies at the sites sampled. The same pattern holds true under the LTRMP sampling. The

mean density of mayflies increased in Pools 4, 13, and 26, while decreasing in the other study areas. Densities

of fingernail clams declined in all study areas. Major declines in the densities of fingernail clams were seen in

Pool 8 and La Grange Pool. Sandusky and Sparks (1979) found that elevated concentrations of ammonia may

have been a partial cause of the decline of fingernail clams in Pool 19 in 1976–77. Ammonia concentrations

may also have influenced the decline of fingernail clams in Pool 8 and La Grange Pool of the Illinois River.

Declines were not as dramatic in Pools 4 and 13. 

Before the decline of fingernail clams in the mid-1950s in the Illinois River, La Grange Pool contained the

highest mean densities of fingernail clams at the sample sites, followed distantly by Pools 8 and 13. The Open

River had no fingernail clams at the sample sites—past or present—probably because of a lack of suitable

habitat in the Open River study area. Since LTRMP sampling began in 1992, Pool 13 fingernail clam densities

far exceed those found in any of the other study areas.

Data from all study reaches combined showed that mayfly population trends were variable in the different

aquatic areas sampled—densities increased in contiguous backwater, side channel, and tributary delta lake

(Lake Pepin) aquatic areas and decreased in impounded areas and main channel borders. Fingernail clam

densities declined in all aquatic areas sampled, except for side channel aquatic areas where they increased in

mean densities from past to present.

Acknowledgments

The Long Term Resource Monitoring Program is a cooperative effort by the Biological Resources Division

of the U.S. Geological Survey, the U.S. Army Corps of Engineers, the Minnesota Department of Natural

Resources, the Illinois Department of Conservation, the Illinois Natural History Survey, the Iowa Department

of Natural Resources, the Missouri Department of Conservation, and the Wisconsin Department of Natural

Resources. Monitoring is conducted by the participating State resource management and research agencies.

Thanks go to these agencies and field station staff, especially Tim Mihuc, Illinois Department of Natural

Resources, for his comments on this report.

References

Anderson, K. B. 1977. Musculium transversum in the Illinois River and an acute potassium bioassay method

for the species. M.S. thesis, Western Illinois University, Macomb. 79 pp.

Brewer, S. K. 1992. Community structure of benthic macroinvertebrates in Navigation Pool No. 8,

Upper Mississippi River: Comparisons between 1975 and 1990. M.S. thesis, University of

Wisconsin–La Crosse. 47 pp.

Colbert, B. K., J. E. Scott, J. H. Johnson, and R. C. Solomon. 1975. Environmental inventory and assessment

of Navigation Pools 24, 25, and 26, Upper Mississippi and Lower Illinois Rivers: An aquatic analysis.

Technical Report Y-75-2, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg,

Mississippi. 137 pp. + Appendixes
18

Dukerschein, J. T., R. Gent, and J. Sauer. 1996. Recovery of macroinvertebrates by screening in the field: A

comparison between coarse (1.18 mm)- and fine (0.66 mm)-mesh sieves. Journal of Freshwater Ecology

11:61–65.

Elstad, C. A. 1977. Macrobenthic survey of Navigation Pool No. 8 of the Upper Mississippi River, with

special reference to ecological relationships. M.S. thesis, University of Wisconsin–La Crosse. 231 pp.

Emge, W. P., R. C. Solomon, J. H. Johnson, C. R. Bingham, B. K. Colbert, and R. W. Hall. 1974. Physical,

biological, and chemical inventory of twenty-three side channels and four river border areas, middle

Mississippi River. Technical Report Y-74-5, U.S. Army Corps of Engineers, Waterways Experiment

Station, Vicksburg, Mississippi. 163 pp. + Appendixes

Fremling, C. R. 1964. Mayfly distribution indicates water quality on the Upper Mississippi River.

Science 146:1164–1166.

Fremling, C. R. 1973. Factors influencing the distribution of burrowing mayflies along the Mississippi River.

Pages 12–15 in W. L. Peters and J. G. Peters, editors. Proceedings of the First International Conference on

Ephemeroptera. E. J. Brill Publishers, Leiden, Netherlands.

Fremling, C. R. 1989. Hexagenia mayflies: Biological monitors of water quality in the Upper Mississippi

River. Journal of the Minnesota Academy of Science 55:139–143.

Hart, C. A. 1895. On the entomology of the Illinois River and adjacent waters. Bulletin of the Illinois State

Laboratory of Natural History 4(6):149–273.

Hoopes, D. T. 1960. Utilization of mayflies and caddisflies by some Mississippi River fishes. Transactions of

the American Fisheries Society 89:32–34.

Hubert, W. A., G. E. Darnell, and D. E. Dalk. 1983. Evaluation of wintering benthic macroinvertebrates of

Pool 13 of the Upper Mississippi River. U.S. Army Corps of Engineers, Rock Island District, Illinois. Letter

Order NCR-LO-83-C12. 30 pp.

Jude, D. J. 1968. Bottom fauna utilization and distribution of ten species of fish in Pool 19, Mississippi River.

M.S. thesis, Iowa State University, Ames. 238 pp.

Lowenberg, C. 1993. 1989 Systemic land cover/land use data in EPPL7 format. National Biological Survey,

Environmental Management Technical Center, Onalaska, Wisconsin, December 1993. EMTC 93-P008.

6 pp. + 2 diskettes

North Star Research Institute, Environmental Systems Division. 1973. Environmental impact assessment study

of the northern section of the Upper Mississippi River. Contract no. DACW37-73-C-0059 for the St. Paul

District Corps of Engineers, Minneapolis, Minnesota. 295 pp.

Paloumpis, A. A., and W. C. Starrett. 1960. An ecological study of benthic organisms in three Illinois River

flood plain lakes. American Midland Naturalist 64:406–435.

Ranthum, R. G. 1969. Distribution and food habits of several species of fish in Pool 19, Mississippi River.

M.S. thesis, Iowa State University, Ames. 207 pp.
19

Reice, S. R., and M. Wohlenberg. 1992. Monitoring freshwater benthic macroinvertebrates and benthic

processes: Measures for assessment of ecosystem health. Pages 287–305 in Freshwater biomonitoring and

benthic macroinvertebrates, D. M. Rosenberg and V. H. Resh, editors. Chapman and Hall, New York. 

Richardson, R. E. 1921. The small bottom and shore fauna of the middle and lower Illinois River and its

connecting lakes, Chillicothe to Grafton: Its valuation; its sources of food supply; and its relation to the

fishery. Bulletin of the Illinois Natural History Survey 13(15):363–522.

Rosenberg, D. M., and V. H. Resh. 1993. Freshwater biomonitoring and benthic macroinvertebrates. Chapman

and Hall, New York. 488 pp.

Sandusky, M. J., and R. E. Sparks. 1979. Investigations of declines in fingernail clam (Musculium

transversum) populations in the Illinois River and Pool 19 of the Mississippi River. The Bulletin of the

American Malacological Union, Inc.:11–15.

Seagle, H. H., J. C. Hutton, and K. S. Lubinski. 1982. A comparison of benthic invertebrate community

composition in the Mississippi and Illinois Rivers, Pool 26. Journal of Freshwater Ecology 1:637–649.

Seagle, H. H., and F. H. Zumwalt. 1981. Evaluation of the effects of tow passage on aquatic macroinvertebrate

drift in Pool 26, Mississippi River. Upper Mississippi River Basin Association Contract Number 881-305.

Minneapolis, Minnesota. 91 pp.

Steingraber, M. T., and J. G. Wiener. 1995. Bioassessment of contaminant transport and distribution in aquatic

ecosystems by chemical analysis of burrowing mayflies (Hexagenia). Regulated Rivers: Research &

Management 11:201–209.

Thiel, P. A., and J. S. Sauer. 1995. Long Term Resource Monitoring Program procedures: Macroinvertebrate

monitoring. National Biological Service, Environmental Management Technical Center, Onalaska,

Wisconsin, August 1995. LTRMP 95-P002-2. 9 pp. + Appendixes A–G

Thompson, D. 1973. Feeding ecology of diving ducks on Keokuk Pool, Mississippi River. Journal of Wildlife

Management 37:367–381.

Trapp, K. E. 1979. A survey of the benthic community of Lake Pepin and a study of the influence of various

physical factors on the distribution of selected taxa. M.S. thesis, University of Wisconsin–La Crosse. 99 pp.

U.S. Fish and Wildlife Service. 1993. Operating Plan for the Upper Mississippi River System Long Term

Resource Monitoring Program. Environmental Management Technical Center, Onalaska, Wisconsin,

Revised September 1993. EMTC 91-P002R. 179 pp. (NTIS # PB94-160199)
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REPORT DOCUMENTATION PAGE

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February 1999

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4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Mayflies (Ephemeroptera) and fingernail clams (Sphaeriidae) at selected sites in the Upper Mississippi River System

6. AUTHOR(S)

Jennifer S. Sauer

7. PERFORMING ORGANIZATION NAME AND ADDRESS 8. PERFORMING ORGANIZATION

U.S. Geological Survey 

Upper Midwest Environmental Sciences Center

2630 Fanta Reed Road

La Crosse, Wisconsin 54603

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9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

U.S. Geological Survey 

Upper Midwest Environmental Sciences Center 99-P001

2630 Fanta Reed Road

La Crosse, Wisconsin 54603

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Release unlimited. Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161

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Help Desk, 8725 Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or 703-767-9050).

13. ABSTRACT (Maximum 200 words)

As part of the Long Term Resource Monitoring Program (LTRMP) macroinvertebrate component, historical sites (sites where benthic samples were previously

collected by other researchers) were sampled in 1992 through 1998. Historical data on densities of the taxa were obtained from published literature and compared to

data collected by the LTRMP. Temporal trends and spatial distribution in the abundance of mayflies (Ephemeroptera) and fingernail clams (Sphaeriidae) were

examined in Navigation Pools 4, 8, 13, 26, and the Open River reach of the Mississippi River and La Grange Pool of the Illinois River. 

14. SUBJECT TERMS 15. NUMBER OF PAGES

Fingernail clams (Sphaeriidae), Long Term Resource Monitoring Program, mayflies (Ephemeroptera), spatial distribution, 19 pp. + Appendix 

temporal trends

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 OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclassified Unclassified
The Long Term Resource Monitoring Program (LTRMP) for the Upper Mississippi

River System was authorized under the Water Resources Development Act of 1986 as 

an element of the Environmental Management Program. The mission of the LTRMP

is to provide river managers with information for maintaining the Upper Mississippi 

River System as a sustainable large river ecosystem given its multiple-use character.

The LTRMP is a cooperative effort by the U.S. Geological Survey, the U.S. Army Corps

of Engineers, and the States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin.