Western North American Naturalist

Volume 60 Number 1 Article 4

1-20-2000

Chironomidae (Diptera) species distribution related to environmental characteristics of the metal-polluted Arkasas River, Colorado

L. P. Ruse Environment Agency (Thames Region), Reading, England

S. J. Herrmann University of Southern Colorado, Pueblo, Colorado

J. E. Sublette Tucson, Arizona

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Recommended Citation Ruse, L. P.; Herrmann, S. J.; and Sublette, J. E. (2000) " (Diptera) species distribution related to environmental characteristics of the metal-polluted Arkasas River, Colorado," Western North American Naturalist: Vol. 60 : No. 1 , Article 4. Available at: https://scholarsarchive.byu.edu/wnan/vol60/iss1/4

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Western North American Naturalist 60(1), pp. 34–56

CHIRONOMIDAE (DIPTERA) SPECIES DISTRIBUTION RELATED TO ENVIRONMENTAL CHARACTERISTICS OF THE METAL-POLLUTED ARKANSAS RIVER, COLORADO

L.P. Ruse1, S.J. Herrmann2, and J.E. Sublette3

ABSTRACT.—Mining in the Upper Arkansas catchment has polluted the river with heavy metals for 140 yr. Pupal and adult chironomid species distribution and sedimentary metal concentrations are provided for 22 stations along 259 km of main river during 1984–85. Complete species identification was achieved only recently. This has produced an unprece- dented record of chironomid species distribution for a comparable length of river in the USA. Chemically or physically perturbed sites had poor species richness compared with the next site downstream, suggesting that larvae may drift through unfavorable habitats to benign ones. Using canonical correspondence analysis, we found species composition to be most strongly related to variables expressing the longitudinal axis of the river (distance/altitude, temperature, latitude), while toxicity to zinc was a significant secondary correlate. These river-related environmental variables accounted for a greater proportion of pupal species variation than for adults. This was considered to result from a proportion of adults emerging from habitats beyond the main river. Multivariate analysis identified metal-tolerant and -intolerant species. Generic data revealed the same major trends but indicator taxa were lost. The study provides a disturbed-state reference for monitoring effects of remedial actions begun in 1991, and for comparisons with other Colorado rivers.

Key words: Chironomidae, heavy metals, multivariate analysis, pupal exuviae, adults, spatial distribution, sediments, species richness.

The Arkansas River in Colorado has been can be made easier and more efficient by sam- polluted by heavy metals since mining began pling pupal exuviae, compared with larvae (Fer- in 1859. Remedial action on the most affected rington et al. 1991). Although exuviae will sites started in 1991. There have been many remain afloat for 2–3 d after adult emergence, descriptive and experimental studies of pollu- they do not drift far before entrapment at river tion effects on benthic macroinvertebrates margins or midstream obstacles (McGill 1980, inhabiting the first 30 km of the river by Ruse 1995a). Exuvial collections should there- researchers of the Bureau of Reclamation and fore be representative of local adult emergence, Colorado State University (e.g., Roline and integrated over a few days before sampling. Boehmke 1981, Roline 1988, Kiffney and In 1983 a major surge of metal sludge in the Clements 1993, Clements 1994, Clements and Upper Arkansas River affected sites 220 km Kiffney 1994). Typically, invertebrates were downstream (Kimball et al. 1995). Emerging sampled using mesh sizes of 500 µm or greater adult chironomids, and later pupal exuviae, and Chironomidae (non-biting ) were were collected from sites along this length of never identified beyond the subfamily level. the Arkansas River during 1984–85 to investi- Armitage and Blackburn (1985) demonstrated gate the effects of metal pollution on species that specific identification of Chironomidae spatial distribution. At that time many individ- distinguished varying degrees of metal pollu- uals could not be identified to species, particu- tion as efficiently as using all macroinverte- larly pupal exuviae. Associations between lar- brate data with chironomids identified only to vae, pupae, and adults from rivers in Colorado subfamily. Clements (1994) has accepted that and neighboring states have since enabled spe- research on metal tolerances of orthocladiine cific identification (Sublette et al. 1998). This species (a subfamily of Chironomidae) is nec- has led to a retrospective investigation of the essary for the Arkansas River. The collection relationship between species distribution and and specific identification of Chironomidae available environmental data using statistical

1Environment Agency (Thames Region), Fobney Mead, Rose Kiln Lane, Reading RG2 0SF, England. 2University of Southern Colorado, 2200 Bonforte Boulevard, Pueblo, CO 81001, USA. 33550 North Winslow Drive, Tucson, AZ 85750, USA.

34 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 35 packages that were not available during the Reservoir reveals that a substantial metal load survey period. This study also differed from is transported there from the Leadville area, other research on the Arkansas River by relat- particularly due to resuspension of river sedi- ing invertebrate distribution to sedimentary ments by snowmelt runoff (Kimball et al. 1995). concentrations of heavy metals rather than The U.S. Environmental Protection Agency water measurements. Kiffney and Clements (EPA) declared the California Gulch catch- (1993) found that suspended metal concentra- ment and the Arkansas River from above AR2 tions in the Arkansas River underestimated to below AR3 a Superfund site in 1983. New availability of metals to benthic macroinverte- water treatment plants on the Leadville Drain brates. Bioaccumulated metal concentrations and California Gulch were in operation by were better related to those measured in sedi- June 1992, and the last major mining opera- mentary minerals and periphyton. This survey tion in Leadville ceased in January 1999. provides the only reference for measuring the Biological Data effect of subsequent remedial actions on the chironomid assemblage of the Arkansas River We collected adult Chironomidae at each and relating their distribution to sedimentary site monthly from May 1984 until September metal concentrations during a period of severe 1985 using sweep net, beating sheet, water- pollution. skimming, hand-picking and ultraviolet light traps. Adults were dissected in absolute METHODS ethanol. Body parts, except for wings and 1 set of legs, were cleared in potassium hydroxide Study Sites and then all parts slide-mounted in Euparal. Twenty-two sites were chosen along 259 Adult Plecoptera and Trichoptera were also km of the East Fork (EF) and Arkansas River collected and are reported in the following (AR) between Climax and Pueblo, east of the paper (Ruse and Herrmann 2000). Continental Divide in central Colorado (Fig. We sampled chironomid pupal exuviae using 1). We adopted sites EF1 downstream to AR9 the “Thienemann net technique” (Thiene- from those surveyed by the Bureau of Recla- mann 1910): a 200-µm-mesh net attached to a mation and reported by Roline (1988). Other circular frame on a pole is used to collect float- biological surveys of the Upper Arkansas ing debris accumulating behind obstacles at catchment have adopted the same site codes, river margins. This method supplemented but since these may refer to different loca- adult collections during a 3-month visiting tions, care should be taken when cross-refer- scholarship by the senior author. Each site was encing with previous publications. sampled in July, August, and September 1985. Metal-rich water enters East Fork between The broad emergence period by many tem- EF1 and EF2 via Leadville Drain, but the perate, lotic species of Chironomidae should greatest source of metals to the catchment ensure that a large proportion of species pre- comes from California Gulch between AR2 sent over the whole year are represented by and AR3 (Kimball et al. 1995). This survey this frequency of sampling (Ruse and Wilson occurred between 2 major metal sludge surges 1984, Ruse 1995b). Samples were refloated, into California Gulch on 23 February 1983 and agitated, and randomly subsampled by sieve. 22 October 1985. Water diverted from the All chironomid pupal exuviae were removed western slopes of the Continental Divide sup- from a subsample and sufficient subsamples plements flows from Turquoise Lake and Twin were sorted to obtain about 200 exuviae, when Lakes, entering the Arkansas River above AR4 possible. Exuviae were mounted on glass micro- and AR9, respectively. Iowa Gulch, and dif- scope slides in Euparal or retained in vials of fuse sources of metals between AR4 and AR8, 70% ethanol. Initially identified to generic carried discharge from an active mine during level, the material remained in excellent con- the study period. Mining affects other tribu- dition until 12 yr later when it became possi- taries to the river downstream of AR8, but ble to determine species. Specific identifica- concentrations of metals are much lower than tion was achieved by comparing exuviae with those found upstream. The Arkansas River those obtained from adult rearings of larvae was impounded above AR19 by the Pueblo and pupae collected subsequently from the Dam in 1974. Sediment analysis of Pueblo Arkansas River and neighboring catchments in 36 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Fig. 1. Upper Arkansas River sampling points.

Colorado and New Mexico. The associated tum types, among 5 size classes, were assessed material is held by author JES. Unassociated visually. Latitude, longitude, altitude, slope, and pupal species are designated by the suffix n-P. distance downstream from EF1 were obtained from maps. Environmental Data We determined metals from 2 samples of At each site water temperature was recorded submerged fine sand taken at each site during once during each monthly visit to collect adult 18–19 October following the 2nd metal sludge . The 3 dominant superficial substra- surge into California Gulch. These data still 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 37 served to characterize the relative contamina- number of individuals identified from a site. tion of sites by metals emanating from Lead- Species recorded at 1 site only were omitted ville mines. A 25-mm-diameter PVC pipe was from CCA in case of spurious association with inserted to a depth of 15 cm. Sediments were a coincidental extreme environmental mea- dried at 70°C for 48 h and ground with a mor- surement; their distributions are recorded in tar and pestle until they passed through a the Appendix. An ordinal value representing 250-µm-mesh sieve. Metals were extracted relative variation in substratum between sites from triplicate subsamples of approximately was obtained by assuming a mean particle size 500 ± 0.1 mg using a sequence of hot diges- for each of 3 categories: boulder/bedrock (215 tions and evaporations with nitric and hydro- mm), rubble/gravel (9.5 mm), and sand (0.25 chloric acids (Caravajal et al. 1983). A reagent mm). The dominant substratum was assumed blank was prepared before and after each set to cover 50% of the site, and the next 2 re- of 6 sediment digestions for a site and taken corded substrata were assumed to cover 30% through the same protocol prior to metals and 20% of the site, respectively. Mean parti- determination. Determination of lead (Pb), iron cle size at each site was calculated from the (Fe), manganese (Mn), zinc (Zn), and copper sum of products of size times proportional (Cu) by flame atomic absorption spectrometry coverage. To account for the ameliorating effect followed the methods of Mahan et al. (1987). of increased hardness on metal toxicity to Cadmium (Cd) was measured by electrother- biota, we calculated EPA hardness-based water mal atomization atomic absorption spectrome- quality criterion for Zn (Clements and Kiffney try (Sandoval et al. 1992). The mean concen- 1995). Water hardness was not measured dur- tration of 6 samples from each site was used in ing this survey, but data were available for subsequent data analysis. sites EF1 to AR9 (Roline and Boehmke 1981, Clements and Kiffney 1995) and for inlet and Data Analysis outlet flows of Pueblo Reservoir (Herrmann Species abundances for samples from the and Mahan 1977). The presence of carbonate same site were combined for both pupal and rocks between AR10 and AR12 and river- adult data sets so they could be related to exposed deposits of calcium and magnesium environmental characteristics recorded on only near AR16 (Kimball et al. 1995) was also taken a single occasion. Spatial variation in these into account when estimating water hardness. data sets was directly compared with environ- For each site, we divided the observed sedi- mental variation using canonical correspon- mentary Zn-loading by the criterion value for dence analysis (CCA; Ter Braak and Prentice assumed water hardness. Resultant ratios 1988). CCA selected the linear combination of were classified into an ordinal scale of toxicity environmental variables achieving the maxi- to Zn: <2.0 = 1, 2.0–9.9 = 2, 10.0–19.9 = 3, mum separation of species by multiple regres- 20.0–39.9 = 4, >39.9 = 5. These broad bands sion along the 1st axis. Subsequent axes were reduced the effect of imprecise hardness esti- extracted from the residual variation to maxi- mates. Environmental data were not trans- mize dispersion of species, provided they formed for CCA; measurements of tempera- were uncorrelated to previous axes. Signifi- ture, slope, Zn toxicity, total Mn, and total Fe cance of the regression between biological and were normally distributed. Latitude and longi- environmental data was tested against the pos- tude values were decimalized and only the sibility of a random association by comparing maximum water temperature recorded at each the F-ratio with 99 unrestricted Monte Carlo site was used. Environmental data were stan- permutations of these data (Ter Braak 1990). A dardized to have a mean of zero and unit vari- probability of ≤0.05 was considered signifi- ance to remove arbitrary variation in units of cant. Forward stepwise regression was used to measurement. CCA species scores were objectively select variables, one at a time, weighted mean sample scores (CANOCO ver- according to the amount of biological variation sion 3.1 scaling + 2). The analysis was there- each explained. Selection stopped when there fore sensitive to relative variation between was no significant increase in explained varia- sites, and it was not necessary to have precise tion, tested against Monte Carlo permutations. data on particle size or water hardness to Before analysis, we converted chironomid relate these characteristics to trends in species species abundances to percentages of the total distribution. 38 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Direct statistical comparisons of pupal and Lake confluence, and then declined until AR10. adult species proportions were made using a Species numbers were high at AR11–AR12 χ2 test of independence (Sokal and Rohlf 1981). and depleted below Pueblo Reservoir at The null hypothesis was that proportions of AR19. was the dominant sub- each species collected were independent of family throughout the survey. There were no sampling method, aquatic netting, or aerial obvious downstream trends in total or subfam- netting. Pupal species unassociated with reared ily species richness except for the absence of adults were excluded, as were species with ex- Diamesinae below AR12. Classifying pupal pected counts <5 in both data sets. exuviae according to presumed feeding modes of their associated larvae (Table 2) revealed a RESULTS dominance by algal grazers at all sites (Fig. 3). Predators increased from AR13 until Pueblo Environmental Data Reservoir. Detritivores were present in low The obtuse-angled line of the main river proportions except at AR10. Filterers appeared prevented latitude or longitude having the from AR16 to AR18. simple linear relationship with distance that ORDINATION.—Stepwise regression selected altitude had (Table 1). The river gradient was distance downstream, maximum temperature, reduced at the last 3 sites, but the trend was latitude, and Zn toxicity as significantly corre- variable along most of the watercourse. Mean lated with variation in species composition particle size at the first 11 sites was often among sites. Altitude was also significant but smaller than at downstream sites. Site AR10 highly correlated with distance and was ex- was characterized by a steep gradient and tor- cluded to prevent multicollinearity (variation rential flow over a substratum dominated by inflation factor = 189; Ter Braak 1990). The 4 bedrock, boulder, and rubble. Maximum re- selected variables explained 43.4% of biologi- corded temperatures increased downstream to cal variation in CCA. The species-environ- AR7 but were suppressed below the Twin Lakes ment relationship was significantly different confluence until AR13. Hypolimnion flows from random for the first 2 CCA axes (P = from Pueblo Reservoir lowered temperature 0.01), accounting for 32.9% of all biological at AR19. Sedimentary total Cu was the only variation and 75.7% of explained variation. metal to reach a peak at AR3, below California Species turnover among samples was Gulch, while the next most Cu-contaminated strongly related to change along the longitudi- sites were AR5 and AR7. Zn toxicity, total Zn, nal axis of the river. Dominance of the 1st Mn, and Cd peaked at AR5, AR7, or AR8, all CCA axis compared with the 2nd resulted in reduced-gradient sites compared with AR3, an archlike configuration of sites in Figure 4. AR4, and AR6. Concentrations of sedimentary Gradient lengths for the first 2 unconstrained Fe below California Gulch remained high (biological data alone) axes were 6.24 and 2.82 throughout the river, except at AR12 and s units, respectively. Detrending or reduction AR19, peaking at AR11. of environmental variables did not remove the arching trend, and separation into 2 data sets Pupal Exuviae was impractical for the small number of sam- A total of 10,120 chironomid pupal exuviae ples. The 1st CCA axis was most significantly were identified to 127 species from 22 sites. related to downstream distance (canonical co- Species abundances are presented in Table 2, efficient t-value 5.42, interset correlation 0.97). with authors’ names, for species collected from The 2nd axis was principally related to varia- 2 or more sites. Species and sites in Table 2 tions in maximum temperature (t-value 6.05, are arranged according to the 1st axis of a cor- correlation –0.46) and Zn toxicity (t-value 2.77, respondence analysis (Ter Braak and Prentice correlation –0.29), resulting in lateral spread- 1988) so that downstream turnover in species ing of samples upstream of AR9, at AR13, and composition can be assessed. Species richness below Pueblo Reservoir. Sites EF2 and AR3, was lowest at EF2, below Leadville Drain, then downstream of the most significant metal increased downstream to the richest site at inputs of Leadville Drain and California Gulch, AR2, above the confluence with California respectively, were closely associated. Sites Gulch (Fig. 2). Species richness was poor at AR5–AR8 had the highest Zn toxicity ratios AR3, recovered at the 3 sites below Turquoise and similar species composition, although AR5 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 39 size (mm) dry weight –1 g µ C) ° ( (Deg.) (Deg.) temp. (m) (%) (km) tox. Cu Zn Pb Mn Fe Cd particle 1. Environmental data; mean total metal concentrations are ABLE T Site LatitudeEF1 LongitudeEF2 Max.AR1 39.28AR2 39.27 AltitudeAR3 39.25AR4 106.22 Slope 39.23AR5 106.33 39.22AR6 106.32 13.0 39.20AR7 106.35 Dist. 13.6 39.17AR8 106.35 14.5 39.13AR9 106.35 3042 14.2 Zinc 39.12AR10 106.33 2969 14.4 39.08AR11 106.32 2944 16.1 39.07 Total 1.1AR12 106.30 2905 38.97 17.4 1.1AR13 106.28 2899 38.78 18.1AR14 1.6 106.28 2865 38.53 Total 18.6 106.20AR15 1.4 2835 38.43 0.00 17.8 106.08AR16 1.4 2795 38.40 6.35 16.0 106.02 TotalAR17 1.0 15.5 2771 38.47 7.87 105.82AR18 0.5 11.11 1 16.5 2748 38.43 105.58AR19 1.7 11.18 2 Total 17.5 2743 38.31 105.40 2573AR20 0.8 14.48 2 19.4 38.26 105.25 2 2338 0.7 20.49 13.9 19.2 38.19 Total 105.00 3 2143 0.4 22.86 10.5 19.9 38.19 1.1 104.92 3 2033 25.91 21.5 0.9 6.0 104.70 5 Total 1879 29.08 132 21.5 4.8 157.0 0.6 104.67 4 1746 30.35 935 21.7 0.5 45.85 5 39.7 Mean 1618 19.6 548 0.6 71.75 4 80.0 1535 19.0 2374 320 21.0 104.77 0.6 2 46.6 1497 88.9 129.28 2 0.7 917 72.6 1444 156.59 2 2836 69.8 779.0 0.4 374 47.6 1431 2 41.0 177.80 1679 0.3 824 16.5 2 267.0 195.45 3038 14.0 0.2 865.0 2 824 825 217.80 8981 2392 21.7 0.3 602 451.0 2 228.98 8014 6.8 508 763.0 730 2 15.5 253.74 30400 420 780 6376 0.40 582.0 1 17.6 1149 258.56 5773 401 0.84 1 19.0 1017 12570 176.0 135 31000 161.4 2.97 1 263 18.0 1474 0.90 15760 2.9 112.7 0.57 1 269 30100 9.8 1.37 4.6 368 309 11.0 39.0 3.50 18570 590 59.6 2.70 4.6 332 4.6 4.8 473 36.3 4.6 4.23 12360 129 6.3 4.6 11350 59.1 1.65 123 198 4.6 256 32170 39.5 4.6 448 0.83 28 4.6 12.9 0.73 24.0 438 6910 20740 68 7.8 0.58 399 27370 115.0 4.6 30070 229 1.0 0.52 0.82 10.2 23720 21.9 290 0.50 18690 0.73 21.9 21.9 84 12410 0.35 143 21.9 0.38 21.9 18820 0.78 6810 21.9 3.2 0.08 0.25 3.2 45.3 4.6 40 WESTERN NORTH AMERICAN NATURALIST [Volume 60

TABLE 2. Proportions of pupal exuviae species at each site: 1 = 0.1–4.9%; 2 = 5.0–9.9%; 3 = 10.0–19.9%; 4 = 20.0–39.9%; 5 = 40.0+%. G = Grazer, D = Detritivore, P = Predator, F = Filterer. Trophic Code Species name group Site

EEAAAAAAAAAAAAAAAAAAAA 11111111112 1212345678901234567890 PROC_SUB Procladius subletti Roback P 1 – – 1 – – – 1 –––––––––––––– THIE_FUS Thienemannimyia fusciceps (Edwards) P 1 – – 1 – 1 –––––––––––––––– DIAM_HET Diamesa heteropus (Coquillet) G – – – 11211–––––––––––––– POTT_MON Potthastia montium (Edwards) D 1 – 1 ––––––––––––––––––– PAGA_PAR Pagastia partica (Roback) D 2111–11–1–1–11–––––––– HYDR_FUS Hydrobaenus fuscistylus (Goetghebuer) G 4 5 – 1211111––11–––––––– HYDR_PIL Hydrobaenus pilipes (Malloch) G – – – 1 – – – 1 –––––––––––––– DIPL_CUL Diplocladius cultriger Kieffer D – – – 1 1 1 – 1 –––––––––––––– EUKI_ILK Eukiefferiella ilkleyensis (Edwards) G – 1121111–1–111–1–––––– EUKI_2-P Eukiefferiella sp. 2-P G – 1112111–––1–1–––––––– EUKI_n9 Eukiefferiella n. sp. 9 G 1 1 – 3211–––––1––1–1–––– ORTH_DUB Orthocladius dubitatus Johannsen G – – – 1 – – 1 ––––––––––––––– ORTH_LUT Orthocladius luteipes Goetghebuer G – – 1111–1–1–––––––––––– ORTH_APP Orthocladius appersoni Soponis G – – – 1 – – 1 ––––––––––––––– ORTH_5-P Orthocladius sp. 5-P G – – – 1 ––––1––––––––––––– ORTH_NIG Orthocladius nigritus Malloch G – 3 – 1111–11––11–––––––– ORTH_OBU Orthocladius obumbratus Johannsen G – – – 1 1 1 – 1 1 ––––––––––––– PARA_n3 Paratrichocladius n. sp. 3 G – – 1 –––––––––1––––––––– PSEC_SPI Psectrocladius spinifer (Johannsen) G – – 1 1 – – – 1 –––––––––––––– RHEO_EMI Rheocricotopus eminelobus Sæther G – 311311111–11–––1––––– TVET_PAU Tvetenia paucunca (Sæther) G – – 444111111–11–––11––– CORY_LOB Corynoneura lobata Edwards G – – 1 1 – – – 1 –––––––––––––– CORY_5-P Corynoneura sp. 5-P G –––––1––––––1––––––––– KREN_CAM Krenosmittia camptophleps (Edwards) G – 11111––––––1––––––––– THIE_5-P Thienemanniella sp. 5-P G 1 – 1 1 – 1 –––––––––––––––– POLY_n1 n. sp. 1 D 1 – 11111–11–1–––––––––– TANY_8-P Tanytarsus sp. 8-P D 1 – 1 ––––––––––––––––––– TANY_n5 Tanytarsus n. sp. 5 D – – 1 1 ––––––––1––1–––––– BRUN_EUM Brundiniella eumorpha (Sublette) P ––––––1–1––––––––––––– CRIC_BIF Cricotopus bifurcatus Cranston & Oliver G –––––––11––––––––––––– CRIC_n18 Cricotopus n. sp. 18 G – – 1 1 – 112211–211–––1––– CRIC_19P Cricotopus sp. 19-P G ––––––11–––––––––––––– HETE_MAE Heterotrissocladius maeaeri Brundin D ––––––11––1–1––––––––– ORTH_FRI Orthocladius frigidus (Zetterstedt) G 4311154445411––1–––––– KREN_HAL Krenosmittia halvorseni (Cranston & Oliver) G ––––––112111–––––––––– SERG_ALB albescens (Townes) P 1––1–––2–––––––––––––– CRIC_TRE Cricotopus tremulus (Linnaeus) G – – 1111111–12111111–1–– CRIC_SLO Cricotopus slossonae Malloch G – – 2 1 1 – 1111212121111––– ORTH_RVA Orthocladius rivicola Kieffer G 11422443323414344442–1 ORTH_MAL Orthocladius mallochi Kieffer G 1 – – 11133322112231111–1 ORTH_10P Orthocladius sp. 10-P G – – – 1 – – 1 ––––––––––1–––– THIE_1-P Thienemanniella sp. 1-P G – – 2121–1–––––1–––111–– POLY_ALB Polypedilum albicorne (Meigen) D – – – 1 – – – 1 –––––1–––––––– MICR_n6 Micropsectra n. sp. 6 D – – – 1 1 1 – – – 1 1 – – 1 – 1 – – –––1

was closer to sites downstream of outflows were associated with high sedimentary metal- from Turquoise Lake and Twin Lakes (AR4, loadings. Krenosmittia camptophleps, which AR9, and AR10). lives among coarse gravel, was found above Species toward the top left of Figure 4 were and below California Gulch but was absent at most abundant at, or restricted to, upstream sites with the highest sedimentary Zn-load- sites. Diplocladius cultriger was present below ings. Other species with an upstream distribu- California Gulch but absent from the most tion and which may be sensitive to high sedi- contaminated sites. Several Orthocladius species mentary Zn concentrations were Eukiefferiella 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 41

TABLE 2. Continued Trophic Code Species name group Site

EEAAAAAAAAAAAAAAAAAAAA 11111111112 1212345678901234567890 BORE_LUR Boreoheptagyia lurida (Garrett) G –––––––––––2––––1––––– MONO_1-P Monodiamesa sp. 1-P D ––––––11–––––1–––––––– EUKI_CLA Eukiefferiella claripennis (Lundbeck) G – – 1111223334332111111– STEN_2-P sp. 2-P D –––––––1–––––––––––––1 PAGA_ORT Pagastia orthogonia Oliver D ––––––––––––11–––––––– BRIL_FLA Brillia flavifrons Johannsen G ––––––––––––1–1––––––– CRIC_BIC Cricotopus bicinctus (Meigen) G – – 1 – – – 1 – 1 –––––––––1111 CRIC_GLO Cricotopus globistylus Roback G ––––––––––––11–––––––– THIE_XEN Thienemanniella xena (Roback) G ––––––––––––1–1––––––– EUKI_1-P Eukiefferiella sp. 1-P G –––––––11–––1–11–11––– ORTH_RUB Orthocladius rubicundus (Meigen) G ––––1––1––1–311211–1–– ORTH_8-P Orthocladius sp. 8-P G ––––––––––––11–1–––––– DEMI_n1 (irmaki) n. sp. 1 P ––––––––––––11–1–––––– ODON_FER Odontomesa ferringtoni Sæther D 1 ––––––1––––11111––1–1 CARD_PLA Cardiocladius platypus (Coquillett) P – – 1 1 – 11111121244443311 CRIC_HER Cricotopus herrmanni Sublette G – – – 1 – 1 – 1 1 – – – 1 2 1 – 1 1 1141 CRIC_INF Cricotopus infuscatus (Malloch) G –––––––––11––––––11111 EUKI_5-P Eukiefferiella sp. 5-P G – – – 1 –––––––––––11––1–1 NANO_SPI Nanocladius spiniplenus Sæther G – – 1 – – 1 1 –––––––––111––1 PARA_LUN Parametriocnemus lundbeckii (Johannsen) G ––––––11––1144123311–1 PHAE_PRO profusa (Townes) D 1 –––––––––––11–1––1111 POLY_LAE Polypedilum laetum (Meigen) D –––––––11–1––1111111–1 PENT_INC Pentaneura inconspicua (Malloch) P ––––––––––––––––––1––1 CRIC_ANN Cricotopus annulator Goetghebuer G –––––––––11–1111323313 CRIC_TFA Cricotopus trifascia Edwards G –––––––––––––1––––1133 CRIC_BLI Cricotopus blinni Sublette G ––––––––––––––1–111154 EUKI_4-P Eukiefferiella sp. 4-P G ––––––––––––––––1–1––– EUKI_COE Eukiefferiella coerulescens (Kieffer) G – – – 1 – 1 –––––––121111111 RHEOCRn1 Rheocricotopus n. sp. 1 (nr. chalybeatus) G ––––––––––––––––––11–– TVET_VIT Tvetenia vitraces (Sæther) G ––––––––––1––1–11111–1 HELE_1-P Heleniella sp. 1-P G ––––––––––––––1––1–––– LOPE_HYP Lopescladius hyporheicus Coffman & Roback D ––––––––––––––––1311–1 THIE_3-P Thienemanniella sp. 3-P G –––––––––––––––––243–– CHIR_DEC decorus Johannsen D –––––––1–––––––11–11–1 CYPH_GIB gibbera Sæther D –––––––––––––1–––––1–1 DICR_FUM fumidus (Johannsen) D –––––––––––––1––––––11 MICR_PES sp. D –––––––––––––––––––1–1 POLY_PAR Polypedilum parascalaenum Beck D ––––––––––––––––––11–1 SAET_n1 n. sp. 1 D –––––––––––––––––––1–1 PSEU_PSE Pseudochironomus pseudoviridis (Malloch) D ––––––––––––––––––––11 CLAD_2-P Cladotanytarsus sp. 2-P D –––––––––––––––––––111 RHEO_n4 Rheotanytarsus n. sp. 4 F –––––––––––––––––112––

n. sp. 9 and Tanytarsus n. sp. 5. Toward the spring (Tokeshi 1995) but was collected in bottom left of Figure 4 are species found at August at AR2 and AR6. Orthocladius frigidus sites with highest potential Zn toxicity such as was found at all sites upstream of AR12 and Krenosmittia halvorseni, in contrast to its con- was most abundant in East Fork and from AR4 gener. Brundiniella eumorpha may have to AR9. Orthocladius mallochi, O. rivicola, occurred at the most Zn-toxic sites due to the Cricotopus slossonae, C. tremulus, and Eukief- presence of numerous small springs. Hydro- feriella claripennis were the most widespread baenus pilipes is known to emerge in early and evenly distributed species throughout the 42 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Fig. 2. Pupal subfamily species richness at each site. main river, apparently unaffected by high Zn Species toward the far right of Figure 4 were toxicity. In the bottom right quarter, Cardio- more abundant downstream of AR11. The cladius platypus was also present at most sites orthoclads Cricotopus trifascia, C. blinni, Lopes- but particularly abundant below AR12 until cladius hyporheicus, and Thienemanniella sp. Pueblo Reservoir. Some species found at down- 3-P and several were restricted stream sites were also present upstream of to these downstream sites. Species located in AR5 and largely absent at the most toxic sites. the top right cluster were most associated with These included Eukiefferiella coerulescens, E. the 2 sites downstream of Pueblo Reservoir. sp. 5-P, Nanocladius spiniplenus, and Phaeno- Adults psectra profusa. In the lower half of Figure 4, the diamesine Pagastia orthogonia, the ortho- Seventeen surveys provided 3896 adult clads Brillia flavifrons, Cricotopus globistylus, Chironomidae comprising 198 species. In addi- Thienemanniella xena, and Orthocladius sp. 8- tion, adult Diamesa leona Roback and D. caena P, and the chironominine Demicryptochirono- Roback were collected nonrandomly from mus (irmaki) n. sp. 1 were restricted to 2 or 3 shelf ice and boulders during winter (Herr- sites at intermediate elevations from AR11 to mann et al. 1987) and excluded from this AR13. These sites, in the driest part of the analysis. Species abundances are presented in catchment, receive high inputs of dissolved Table 3, with naming authors, for those species major ions from soft sedimentary and carbon- found at 2 or more sites, and rearranged by ate rocks. Parametriocnemus lundbeckii was correspondence analysis. There was no obvi- more widely distributed than these species ous downstream trend in species richness (Fig. but was most abundant at AR11 and AR12. 5). Fluctuations resembled those exhibited by 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 43

Fig. 3. Proportions of pupae classified by trophic group at each site.

pupal data except at sites AR5, AR7, and which was dominated by Chironominae, and AR20. Species richness fell downstream of at AR18 where they were the rarest trophic Iowa Gulch at AR5 and increased at the next 2 group. Grazers and detritivores were co-domi- sites. Both Leadville Drain and California nant at AR12. Filterers were an important Gulch preceded falls in species richness while component of the chironomid assemblage at the poorest site was AR10. Species richness AR18 but, as with pupal data, were absent declined after Pueblo Reservoir, contrasting below Pueblo Reservoir. the recovery exhibited by pupae from AR20. ORDINATION.—Latitude, Zn toxicity, and Adult data confirmed the dominance by Ortho- particle size were the only significant vari- cladiinae among pupal exuviae although ables selected, explaining 22.3% of biological species of Chironominae were relatively more variability. Total Fe was interchangeable with abundant. Adult Diamesinae were found at all Zn toxicity, but the latter was used to maintain sites except AR18 (if D. leona is included), comparability with pupal data. Only the 1st while Tanypodinae and Podonominae were CCA axis was significant (P = 0.01), explaining also more widely collected compared with 9.8% of all biological variation and 43.8% of pupal data. the species-environment relationship. Length- The relative abundance of Chironominae is wise variation, best explained by latitude, was reflected in the increased importance of detri- again the dominant influence along the pri- tivores in Figure 6 compared with pupal data. mary axis (t-value 19.2, correlation –0.94). Zn Grazers were dominant at all sites except AR5, toxicity (t-value 2.3, correlation –0.44) and 44 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Fig. 4. CCA ordination of pupal data. Arrows indicate importance and direction of maximum change in species com- position among samples as the variable increases. Open circles used for sites, points for species. Species codes from Table 2. particle size (t-value 6.3, correlation 0.11) were tum particle sizes and site EF1 had the small- also significantly related to biological variation est. Site AR10 had the largest particle size, but along the first axis. its position reflects the greater importance of There was no arch effect in Figure 7 be- latitude and Zn toxicity. The association be- cause the first 2 axes were of similar impor- tween Krenosmittia halvorseni and the most tance (4.41 and 3.56 s units). A north–to–south Zn-toxic sites revealed by pupal data was sup- distribution of sites occurred along the 1st ported by adult collections. Also in the top left axis, with lateral spreading of closely situated of Figure 7, two cold-water adapted species, upstream sites. Sites with the highest Zn toxi- Paracladius alpicola and viridula, city were positioned together in the top left of as well as Orthocladius subletti and Polypedi- Figure 7, while the least toxic sites were lum trigonus were all present at AR7 (high Zn placed diagonally opposite. Sites AR12–AR16 toxicity) and AR11. Adult Micropsectra nigrip- and AR19 had relatively large mean substra- ila were collected from East Fork downstream 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 45

Fig. 5. Adult subfamily species richness at each site. to AR16, dominating collections from AR5, bicinctus and Parametriocnemus lundbeckii whereas pupal exuviae were found only at were both widely distributed except at Zn- AR11. Gymnometriocnemus brumalis is proba- toxic sites; however, their pupal exuviae were bly terrestrial; it was absent from pupal collec- found at toxic sites. Adult and pupal C. infus- tions but adults were collected from AR4, catus had a downstream distribution but toler- AR5, and AR12, between 2000 and 3000 m. ated metals at AR8. Smittia n. sp. 3, Polypedilum Adults of Cricotopus coronatus were found at digitifer, and Micropsectra logani (pupae at sites with high Zn toxicity or at intermediate AR6) were collected from the first 4 sites altitude. Both adult and pupal collections of above California Gulch and then disappeared Orthocladius frigidus and O. nigritus indicated until AR17, or further downstream. that these were montane species tolerant of Independence of Zn concentrations downstream of California Sampling Method Gulch. Among downstream-distributed species In a test for association between pupal and located toward the lower right of Figure 7 adult data, χ2 = 5908.5, significantly (P < 0.001) χ2 were a few species that also occurred upstream exceeding the critical .05[65] of 106.0 for of AR4. Procladius subletti and Limnophyes n. associated data. Species most affected by the sp. 3 were collected at EF1 and AR2, respec- method of sampling were Micropsectra nigrip- tively, were absent at the most Zn-toxic sites, ila (pupae fewer than expected, adults greater), and were present in the vicinity of Pueblo Rheotanytarsus n. sp. 1 (pupae greater, adults Reservoir. Pupal exuviae of P. subletti, how- fewer), Orthocladius rivicola (adults fewer), O. ever, were collected at AR6. Adult Cricotopus obumbratus (adults greater), Diamesa heteropus 46 WESTERN NORTH AMERICAN NATURALIST [Volume 60

TABLE 3. Proportions of adult species collected at each site (see Table 2 for explanation). Trophic Code Species name group Site

AAAAAAAAAAAAAAAEEAAAAA 12111111 11 1 9078345656789121212340 LARS_PLA Larsia planensis (Johannsen) P ––––––––1–––––1––––––– PARO_KIE Parochlus kiefferi (Garrett) P –––––––––––––––11–1––– DIAM_DAV Diamesa davisi Edwards G –––––––––1––2–––––––34 DIAM_SPI Diamesa spinacies Sæther G ––––––––––––2––––––23– PAGA_ORT Pagastia orthogonia Oliver D ––––––––1–––––1––––––– PAGA_PAR Pagastia partica (Roback) D ––––––––––––111–––––1– ODON_FER Odontomesa ferringtoni Sæther D ––––––––––1–––1–––––1– HYDR_FUS Hydrobaenus fuscistylus (Goetghebuer) G –––––––––––––111––––1– ACRI_NIT Acricotopus nitidellus (Malloch) D –––––––––2––12–––––––– BRIL_FLA Brillia flavifrons Johannsen G –––––––––––––––2–31–1– CRIC_BIF Cricotopus bifurcatus Cranston & Oliv. G ––––––––11–––––––2–1–– CRIC_TIB Cricotopus tibialis (Meigen) G –––––––––––12––––––––– CRIC_GLO Cricotopus globistylus Roback G ––––––––––––1–1––––––– EUKI_n4 Eukiefferiella n. sp. 4 G –––––––––––––1–––1–––– ORTH_FRI Orthocladius frigidus (Zetterstedt) G ––––––1–121421–341––3– ORTH_SUB Orthocladius subletti Soponis G ––––––––––11–1–––––––– ORTH_WIE Orthocladius wiensi Sæther G ––––––––1–––––––––2––– PARA_ALP Paracladius alpicola (Zetterstedt) G ––––––––––1––1–––––––– PARA_n3 Paracladius n. sp. 3 G ––––––––––––––1––1–––– PSEC_SPI Psectrocladius spinifer (Johannsen) G ––––––––––1––––1––––1– RHEOCRn1 Rheocricotopus n. sp. 1 (nr. chalybeatus) G –––––––––1–111–1––1––– RHEO_EMI Rheocricotopus eminelobus Sæther G ––––––––1––––1–12111–– TOKU_ROW Tokunagaia rowensis (Sæther) D ––––––––––––––11–3–––– TVET_PAU Tvetenia paucunca (Sæther) G –––––––––––––––1211––– LIMN_ELT Limnophyes eltoni (Edwards) G –––––––––––––––12–2––– LIMN_NAT Limnophyes natalensis (Kieffer) G ––––––––––––––––––111– GYMN_BRU Gymnometriocnemus brumalis (Edwards) G ––––––––2–––––1–––––1– KREN_n1 Krenosmittia n. sp. 1 G ––––––––––––––––1––1–– KREN_HAL Krenosmittia halvorseni (Cranston & Oliver) G –––––––––111–––––––––– LIMN_n1 Limnophyes n. sp. 1 G –––––––––1––1–––4131–– LIMN_n2 Limnophyes n. sp. 2 G –––––––––––––––1––2–1– METR_BRU Metriocnemus brusti Sæther G –––––––––––1–––––1–1–– LIMN_n4 Limnophyes n. sp. 4 G ––––––––––––––––111––– PARAPSEU Paraphaenocladius pseudirritus nearticus Saether & Wang D –––––––––––1––––––13–– PARAPNAS Paraphaenocladius nasthecus Sæther D ––––––––––1––––––––11– SMIT_ATE Smittia aterrima (Meigen) G ––––––––––––1–1––––––– SMIT_n1 Smittia n. sp. 1 G –––––––––––––1–––––––2 THIE_ELA Thienemaniella spp. G ––––––––––––––1––11––– CHIR_RIP Meigen D –––––––––––11––––––12– CLAD_VIA Cladopelma viridula (Linnaeus) D ––––––––––1––1–––––––– DICR_NER Dicrotendipes nervosus (Staeger) D ––––––––––1–––––––––1– PARA_NIX nixe (Townes) P ––––––––––––11–––––––– POLY_ALB Polypedilum albicorne (Meigen) D ––––––––1–11–––2111––– POLY_TRI Polypedilum trigonus Townes D ––––––––––1––1–––––––– TANY Tn2 Tanytarsus n. sp. 2 D ––––––––––1––––2––1––– CRIC_COR Cricotopus coronatus Hirvenoja G – – 1 – 1 – – – 1333221––––––– CRIC_SLO Cricotopus slossonae Malloch G – – 1 – – 1 – – 1 – – 1111–111–1– CRIC_SYL Cricotopus sylvestris (Fabricius) G ––––1–––––1–111––––––– EUKI_n9 Eukiefferiella n. sp. 9 G 1 ––––––––––111–––11––– ORTH_NIG Orthocladius nigritus Malloch G –––––1––1––1––––––––2– LIMN_ASQ Limnophyes asquamatus Andersen G –––––1–––––11––1––1–1– PSEU_FOR Pseudosmittia forcipata (Goetghebuer) G –––––1–––––1–2–––––11– 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 47

TABLE 3. Continued. Trophic Code Species name group Site

AAAAAAAAAAAAAAAEEAAAAA 12111111 11 1 9078345656789121212340 SERG_ALB Sergentia albescens (Townes) P –––––1––111–––1–––1––– MICR_POL Micropsectra polita (Malloch) D –––––––2––41––2––––––– PARA_SMI Paramerina smithae (Sublette) P – – – 1 –––––1––––––––1––– DIAM_HET Diamesa heteropus (Coquillet) G 4 1 – – 1 – – – 2 4 – – 2 –––––1–1– PSEU_PER Pseudodiamesa pertinax (Garrett) D ––––1––––––––11––––––– EUKI_CLA Eukiefferiella claripennis (Lundbeck) G 1 1 1 – 1 1 – 11112212–221–12 ORTH_MAL Orthocladius mallochi Kieffer G 4 1 – – 4 2 – – 12313111–21–1– CHAE_n1 Chaetocladius n. sp. 1 G ––––1–––1–––––––––––1– SMIT_n3 Smittia n. sp. 3 G – – 1 ––––––––––––11––––– MICR_NIG Micropsectra nigripila (Johannsen) D 1 – – – 1 – 1342–––2–2––111– MICR_LOG Micropsectra logani (Johannsen) D – 1 –––––––––––––1–1–––– CRIC_TRE Cricotopus tremulus (Linnaeus) G – – – 1 1 1 ––––––111–11–––2 CHIR_MAT Chironomus maturus Johannsen D – – – 1 1 ––––––––11––3–––– BORE_LUR Boreoheptygia lurida (Garrett) G ––––––14–––121–––11–14 POLY_n1 Polypedilum n. sp. 1 D – – 1 – 1 1 – 1 – – 1 1 – – – 1 – 1 1–1– ORTH_RVA Orthocladius rivicola Kieffer G 111131311111111111111– PSIL_n1 Psilometriocnemus n. sp. 1 G –––––1––––––––––––––1– PHAE_PRO Phaenopsectra profusa (Townes) D – 1 1 – – 1 – 1 – – 1 1 1 ––––1–––– PROC_CUL Procladius culiciformis (Linnaeus) P 1 – – 1 –––––––––1–––––––– PROC_FRE Procladius freemani Sublette P –––1–––––1–––––––––––– PROC_SUB Procladius subletti Roback P – – – 2 –––––––––1–1–––––– DIAM_ANC Diamesa ancysta (Roback) G ––––––41–111––––––1––– HYDR_PIL Hydrobaenus pilipes (Malloch) G 1 1 ––––––––2––––––––––– CARD_PLA Cardiocladius platypus (Coquillet) P – – 111311–2–1–1–1–––2–– CRIC_BIC Cricotopus bicinctus (Meigen) G 1 – 1 1 – – – 1 –––––1–11––––– CRIC_HER Cricotopus herrmanni Sublette G – – 413333–––1–221–––––– CRIC_INF Cricotopus infuscatus (Malloch) G 1131–––––––11––––––––– PARA_CNV Paracladius conversus (Walker) G 1 – 1121––––1––11––––––– PSEC_BMS Psectrocladius barbimanus (Edwards) D –––––1–––––––1–––––––– TVET_VIT Tvetenia vitraces (Sæther) G – – – 1 – 1 – 1 ––––1––––1–––– LIMN_n3 Limnophyes n. sp. 3 D – – 1 –––––––––––––––1––– PARA_LUN Parametriocnemus lundbeckii (Johannsen) G 1 – 1 1 – 1 1 –––––11–11––––– CHIR_DEC Chironomus decorus Johannsen D – – 1211–––11––111–––––– CHIR_ATR (Townes) D –––––1–––––––1–––––––– CYPH_COR Cyphomella cornea Sæther D – 1 – – 1 ––––––––1–––––––– DICR_FUM Dicrotendipes fumidus (Johannsen) D 1 2 – – 1 –––––––––4––––––– POLY_DIG Polypedilum digitifer Townes D 1 – – 1 –––––––––––1–––––– PSEU_RIC Pseudochironomus richardsoni (Malloch) D – – – 1 – – – 1 –––––1–––––––– PROC_BEL Procladius bellus (Loew) P 1 – – 1 – – – 1 –––––––––––––– ABLA_MAL Ablabesmyia mallochi (Walley) P 1 – – 1 –––––––––––––––––– CRIC_ANN Cricotopus annulator Goetghebuer G – – 323443––––11–––––––– CRIC_TFA Cricotopus trifascia Edwards G 2121–––––––––––––––––– CRIC_BLI Cricotopus blinni Sublette G 3431–––––1–––––2–––––– EUKI_COE Eukiefferiella coerulescens (Keiffer) G 1 2 –––––1–––––––––––––– ORTH_TRI Orthocladius trigonolabis Edwards G 1 1 1 – – – 1 1 ––––––––– –––– ORTH_OBU Orthocladius obumbratus Johannsen G 4 1 –––––1–––––––––––––– PARA.RUV Paratrichocladius rufiventris (Meigen) G ––––11–––––––––––––––– POLY_LAE Polypedilum laetum (Meigen) D – – 1111–1––––––1––––––– POLY_SUL Polypedilum sulaceps Townes D – – 1 1 1 ––––––1–––––––––– POLY_SCA (Schrank) D – – 1311–1–––––––1––––1– STIC_MAR marmoreus (Townes) D – – 1 1 –––––––––––––––––– CLAD_n1 Cladotanytarsus n. sp. 1 D – 1 – 1 –––––––––––––––––– RHEOTAn1 Rheotanytarsus n. sp. 1 F – – 1 4 – – – 2 ––––––––––––1– 48 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Fig. 6. Proportions of adults classified by trophic group at each site.

(adults greater), and Polypedilum scalaenum the 2 variables were independent (Pearson (adults greater). Species sampled equally well correlation –0.18, r.05[20] = 0.42) and all vari- as pupae and adults (combined χ2 < 1.6) were ance inflation factors were below 1.1. Sites Pagastia partica, Cricotopus herrmanni, Tvetenia were approximately ordered from warmest to vitraces, Cricotopus blinni, and Phaenopsectra coolest along the diagonal of the temperature profusa. vector in Figure 8. Almost at right angles was Effect of Classification Level a gradient of metal contamination; AR3 had almost twice the Cu concentration of the next Generic adult data were ordinated to inves- most contaminated samples from AR5 (Table tigate the influence of taxonomic level because 1). Except for AR3, sites were closer to the of the large number of species in this data set. origin of Figure 8 than they were in a species Stepwise regression selected maximum water temperature, total Cu, and mean particle size, CCA. No genera were solely associated with explaining 25.1% of generic adult chironomid AR3; the closest genera were Paraphaenocla- variability. The first 2 axes were significant dius (2 species used for adult CCA), Metrioc- (both P = 0.04), together explaining 18.3% of nemus (1 sp.), and Krenosmittia (2 sp.). These biological variation. The primary axis was sig- genera were found at several upstream sites nificantly explained by temperature (t-value but particularly the most metal-contaminated 6.93), while all 3 variables significantly ex- (AR3–AR8). In the lower half of Figure 8, plained the 2nd axis, particle size being the Parametriocnemus (1 sp.) exhibited metal intol- least important. Despite the overlap of tem- erance revealed by species CCA, as did Tvete- perature and particle size vectors in Figure 8, nia (2 sp.). Responses of other adult species, 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 49

Fig. 7. CCA ordination of specific adult data. Explanation as for Figure 4, species codes from Table 3.

previously highlighted as metal-intolerant, DISCUSSION have been lost among the conflicting trends of Comparisons of Pupal their congeners within species-rich genera and Adult Data such as Procladius (4 sp.), Cricotopus (13 sp.), and Polypedilum (7 sp.). Orthocladius (8 sp.), An unprecedented description of chirono- Chironomus (4 sp.), Eukiefferiella (4 sp.), and mid species distribution has been provided for Diamesa (4 sp.) were also central to the ordi- 259 km of a major U.S. river. Proportional nation because of counterbalancing species species abundances across the 22 Arkansas distributions. Limnophyes (7 sp.) was associated River sites were not equally represented by with low-temperature sites, as only 2 species samples of pupal exuviae and adults. Greater appeared downstream of AR9, and in small proportions of adult detritivores indicated that proportions. Micropsectra was associated with sources of associated larvae may have metal-impacted sites due to the distribution of included lentic, semi-terrestrial, and terres- M. nigripila and M. polita and despite occur- trial habitats beyond the Arkansas River. The rences of M. logani. absence of small-bodied Corynoneura and 50 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Fig. 8. CCA ordination of generic adult data. Explanation as for Figure 4.

Thienemanniella adults indicated that aerial Site AR18 was observed to have faster current nets were ineffective at catching these midges. than sites below the reservoir. Species sam- The large proportion of predators among pled equally well as adults and pupae may pupal data from sites AR13–AR18 was due to have had broad emergence patterns, being rheophilic Cardiocladius platypus, which may multivoltine or asynchronous. Cool-adapted have been underrepresented in adult collec- Diamesa heteropus, as well as Orthocladius tions. Assuming adult data included individu- obumbratus, were underrepresented as pupae als from external sources, this would explain because their main emergence period had why river-related environmental variables passed before pupal exuviae were collected. accounted for less biological variation than Adults of O. obumbratus were collected from that achieved with pupal data. Despite dis- AR16–AR20 while pupal exuviae were obtained crepancies in expected numbers of species, from cooler stations at AR2–AR7. Micropsec- there were similarities in species distribution tra nigripila, the most abundant adult species, between the 2 life stages. Examples cited were and Polypedilum scalaenum were also better Krenosmittia halvorseni, Orthocladius nigritus, represented in adult collections. Both species O. frigidus, and Cricotopus infuscatus. Both prefer lentic habitats and may have originated pupal and adult collections revealed the pres- from extraneous sources. Rheophilic Rheotany- ence of filterers upstream of Pueblo Reservoir tarsus n. sp. 1 and Orthocladius rivicola were and their absence downstream. Herrmann and the most abundant pupal species and were Mahan (1977) found that turbidity at the outlet underrepresented in adult collections, proba- was typically lower than in the reservoir, or at bly because they were “diluted” by species the inlet, during the first 2 yr of its existence. from other sources. 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 51

Species Richness sampled with 50-µm-mesh nets, has suggested Collections of pupal exuviae typically reveal that Chironomidae actively redistribute them- greater species richness than direct sampling selves and colonize preferred habitats through of stream habitats for larvae (Ferrington et al. drifting, particularly as 1st or 2nd instars. This 1991, Ruse 1995a). The present study obtained behavior would explain the contrast in species greater species richness from adult collections. richness between sites EF2 and AR1, AR3 and This could be explained partly by adults origi- AR4/6, and AR10 and AR11. nating from extrinsic habitats. Additionally, 17 Species Distribution and months of adult sampling would increase the the Effect of Metals number of species obtained compared with 3 months of pupal sampling. The pupal total of Environmental measurements most corre- 127 species compares favorably with species lated with a successive downstream turnover totals for other montane or subalpine streams in species composition (distance/altitude, lati- presented in a review by Lindegaard and tude, and temperature) were aligned with the Brodersen (1995), which gave an average mon- primary CCA axis of both data sets. Pupal data tane species total of 71 (range 26–144). The best reflected a smooth downstream gradient total of 200 adult species was not comparable in species turnover. In a neighboring river, with surveys of larvae or pupal exuviae because Ward (1986) classified 4 zones of species assem- of their uncertain origin. Both pupal and adult blage related to altitudes between 3414 m and data exhibited a decline in species richness at 1544 m, although chironomid taxa showed the 1st site below Leadville Drain and again much greater overlap than did Plecoptera and below California Gulch, the major sources of Trichoptera. A longitudinal zonation among metal pollution. Sites with the highest sedi- Chironomidae was suggested by Ward and mentary concentrations of Zn, Pb, Mn, and Cd Williams (1986) when replaced (AR5, AR7, AR8) had about average species Orthocladiinae in a 36-km-long Canadian river. richness. Other research on the effects of In the Arkansas River pupal Chironominae in- metal-polluted mine drainage on chironomids creased from AR17 downstream, except below has demonstrated a reduction in species rich- the reservoir outlet, but there was no evidence ness (Winner et al. 1980, Armitage and Black- for altitudinal zonation rather than succession. burn 1985, Yasuno et al. 1985, Wilson 1988). The most abrupt changes were anthropogenic: Conversely, Cranston et al. (1997) demonstrated mining, regulation, and impoundment. In the an increase in chironomid species richness pupal CCA, localized effects of metal pollution below a mine adit, which they attributed to a within a 20-km reach were overwhelmed by greater pool of tolerant species in Australia effects of downstream succession along 259 compared with northern, temperate regions. km of the river. The importance of altitude Neither pupal nor adult data conformed to the and latitude to macroinvertebrate species downstream trend of increasing species rich- structure, mediated through their effect on ness found by Ward (1986) in a neighboring temperature, has been demonstrated locally catchment. Pupal and adult data sets revealed by Ward (1986) and globally by Jacobsen et al. a low number of species from site AR10, which (1997). Latitude was strongly related to dis- had the coarsest substratum and a strong cur- tance but, because it changed most between rent. Clements and Kiffney (1994) reported a sites EF1 and AR12, it also had a correlation reduced macroinvertebrate species richness at with chironomid species variability among a site approximately 10 km downstream of our metal-polluted sites. Longitude varied most site AR10. The next site downstream, AR11, between sites AR13 and AR20, where there had the highest number of adult species and was relatively less species variability; conse- the 3rd highest number of pupal species. Lar- quently, it was never selected by forward vae of species avoiding sites with metal inputs regression after latitude had been chosen. In a (EF2, AR3) or with high physical stress (AR10) study of 6 Colorado streams, including the may have drifted through to the next site, Arkansas River, Clements and Kiffney (1995) increasing its species richness. The effect is found that altitudinal variation confounded less dramatic below California Gulch because the effects of metal on benthic macroinverte- of high sedimentary metal concentrations fur- brates. Using CCA, we noted that metal pollu- ther downstream. Williams (1989), who pump- tion still had a significant explanatory value in 52 WESTERN NORTH AMERICAN NATURALIST [Volume 60 our study, even when generic-level adult data was a minor component of the Arkansas River were considered. Herrmann and Mahan (1977) chironomid assemblage, even at the most metal- found that metal-enriched water was reaching polluted sites. C. bicinctus did appear below Pueblo Reservoir, and subsequent research by Leadville Drain at EF2 (adults) and below Kimball et al. (1995) confirmed that metal California Gulch at AR5 and AR7 (pupae), inputs, and their transportation, extend through- while C. infuscatus did not appear until AR8 out 250 km of river. Sites AR3 and AR5–AR8 with a predominantly downstream distribution were extreme examples of metal pollution, (pupae and adults). C. slossonae was absent whereas concentrations of sedimentary Zn at from the 2 most metal-polluted sites on Elam’s remaining sites were still high downstream to run, but was present at all the most polluted Pueblo Reservoir. The work of Kiffney and Arkansas River sites. Eukiefferiella claripennis Clements (1993) revealed that macroinverte- was not found in Elam’s Run, but its presence brates bioaccumulated more Zn and Cd at site at Zn-polluted sites was recorded by the 2 AR5 than at AR3 while the reverse was usually English studies mentioned (Armitage and true for Cu. These results are in accord with Blackburn 1985, Wilson 1988) and was tolerant distributions of chironomid species reported of severely Cu-contaminated (>50 µg L–1) here. streams in southwest England (Gower et al. Metal-tolerant assemblages of chironomid 1994). E. claripennis, distributed extensively species below California Gulch are evident along the Arkansas River, was subdominant to from Tables 2 and 3. Individual species were Orthocladius species within pupal collections highlighted for their tolerance or intolerance, at the most metal-polluted sites. some of which have been connected previ- Species indicated as intolerant of severe ously with metal impacts by other researchers. heavy-metal pollution included some new In the English Pennines, Wilson (1988) found species: Eukiefferiella n. sp. 9, E. sp. 5-P, Limno- a high proportion of Krenosmittia camptopleps phyes n. sp. 3, and Tanytarsus n. sp. 5. E. co- below a Zn-polluted mine adit although the erulescens avoided the most toxic sites and was species was absent from a neighboring river of also reported by Wilson (1988) to be absent at the same catchment which was also Zn pol- Zn-polluted sites. Specific comparison of metal luted. Wilson suspected that metal pollution tolerance, especially across widely separated alone was not determining species distribu- tion. In the Arkansas River this species was river systems, has its limitations. Postma et al. replaced by its congener K. halvorseni at sites (1995) have demonstrated that chironomid pop- with the highest sedimentary Zn-loadings. In ulations from metal-polluted rivers can exhibit the same catchment studied by Wilson, Ortho- less sensitivity to some metals compared with cladius frigidus was found by Armitage and conspecifics derived from unpolluted sites. Blackburn (1985) in moderately Zn-polluted They suggest this has a genetic basis. sites (0.77–1.68 mg L–1) but was absent at Future Study higher concentrations (2.08–7.6 mg L–1). O. frigidus reached its highest proportions at This study of the Arkansas River during sites AR4 and AR8; these sites have recorded 1984–85 provides a reference for assessing suspended Zn concentrations within the mod- changes that have occurred since remediation erate range (Roline and Boehmke 1981, Kim- work began in 1991. Now that Leadville mines ball et al. 1995) but could be exposed to higher have ceased operating, subsequent monitoring concentrations in spring (Clements 1994). The of chironomid species distribution would record study of Elam’s Run in Ohio by Winner et al. how the Arkansas River responds. Biomonitor- (1980) provided evidence of metal tolerance for ing using generic-level data would save time, several Arkansas River species that inhabited provided there was no significant loss of infor- sites AR3–AR8: Orthocladius dubitatus, O. mation. Generic data reduced the amount of obumbratus, Cricotopus bicinctus, C. infuscatus, unexplained species variation that probably Diplocladius cultriger, and Larsia planensis arose from the uncertain origin of the rarer (adult). Waterhouse and Farrell (1985) drew adult species. There was more homogeneity of attention to C. bicinctus being succeeded by generic assemblages between sites, although C. infuscatus along a gradient of declining sensitivity to Cu pollution, or perhaps sus- metal pollution in Elam’s Run. C. bicinctus pended metals, was greater than with specific 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 53 data. Generic data revealed the same 2 major communities? Canadian Journal of Fisheries and gradients, of longitudinal variation and metal Aquatic Sciences 54:1802–1807. CARAVAJAL, G.S., K.I. MAHAN, D. GOFORTH, AND D.E. contamination, identified by specific adult and LEYDEN. 1983. Evaluation of methods based on acid pupal data. Multivariate analysis of 10 benthic extraction and atomic absorption spectrometry for macroinvertebrate data sets by Bowman and multi-element determinations in river sediments. Bailey (1997) led them to suggest that if trade- Analytica Chimica Acta 147:133–150. CLEMENTS, W.H. 1994. Benthic invertebrate community offs were necessary to investigate community responses to heavy metals in the Upper Arkansas variation, it would be better to sacrifice taxo- River Basin, Colorado. Journal of the North Ameri- nomic resolution than quantitative data. An can Benthological Society 13:30–44. analysis of specific- and generic-level chirono- CLEMENTS, W.H., AND P. M . K IFFNEY. 1994. Integrated mid data along a metal-pollution gradient by laboratory and field approach for assessing impacts of heavy metals at the Arkansas River, Colorado. Waterhouse and Farrell (1985) revealed good Environmental Toxicology and Chemistry 13:397–404. agreement when using nonspecific diversity ______. 1995. The influence of elevation on benthic com- indices, but important information was lost if munity responses to heavy metals in Rocky Mountain indicators within species-rich genera were streams. Canadian Journal of Fisheries and Aquatic Sciences 52:1966–1977. relied upon. The importance of specific identi- CRANSTON, P. S . , P. D . C OOPER, R.A. HARDWICK, C.L. fication of chironomid indicators of metal pol- HUMPHREY, AND P.L. DOSTINE. 1997. Tropical acid lution was stressed by Gower et al. (1994) streams—the chironomid (Diptera) response in using CCA, although this was addressed to northern Australia. Freshwater Biology 37:473–483. researchers relying on subfamily chironomid FERRINGTON, L.C., M.A. BLACKWOOD, C.A. WRIGHT, N.H. CRISP, J.L. KAVANAUGH, AND F. T. S CHMIDT. 1991. A data. The metal-related distribution of several protocol for using surface-floating pupal exuviae of species belonging to the genera Cricotopus, Chironomidae for rapid bioassessment of changing Orthocladius, and Eukiefferiella would have water quality. Pages 181–190 in Sediment and stream been lost if identification of Arkansas River water quality in a changing environment: trends and explanation. IAHS Publication 203. pupae and adults had been generic only. Even GOWER, A.M., G. MYERS, M. KENT, AND M.E. FOULKES. among 2 species of Krenosmittia, pupal data 1994. Relationships between macroinvertebrate revealed a distinct difference in metal-related communities and environmental variables in metal- distribution. Generic data would be adequate contaminated streams in south-west England. Fresh- for a large-scale description of environmental water Biology 32:199–221. HERRMANN, S.J., AND K.I. MAHAN. 1977. Effects of im- influences but would have diminished value poundment on water and sediment in the Arkansas when monitoring recovery of individual sites. River at Pueblo Reservoir. Bureau of Reclamation Report REC-ERC-76-19. HERRMANN, S.J., J.E. SUBLETTE, AND M. SUBLETTE. 1987. CKNOWLEDGMENTS A Midwinter emergence of Diamesa leona Roback in the Upper Arkansas River, Colorado, with notes on LPR was in receipt of a Winston Churchill other diamesines (Diptera: Chironomidae). Entomo- Travelling Fellowship in 1985, and his subse- logica Scandinavica Supplement 29:309–322. quent work was supported by the U.K. Envi- JACOBSEN, D., R. SCHULTZ, AND A. ENCALADA. 1997. Struc- ture and diversity of stream invertebrate assem- ronment Agency. SJH and JES received fund- blages: the influence of temperature with altitude ing from the U.S. Environmental Protection and latitude. Freshwater Biology 38:247–261. Agency through the Colorado Department of KIFFNEY, P.M., AND W.H. CLEMENTS. 1993. Bioaccumula- Health (Contract C379551). We are indebted tion of heavy metals by benthic invertebrates at the to Mary Sublette for management of type spec- Arkansas River, Colorado. Environmental Toxicology and Chemistry 12:1507–1517. imens and data tabulation, and to Kent Mahan KIMBALL, B.A., E. CALLENDER, AND E.V. AXTMANN. 1995. for sediment chemistries. The views expressed Effects of colloids on metal transport in a river are the authors’ and do not necessarily repre- receiving acid mine drainage, Upper Arkansas River, sent those of their respective agencies. Colorado, USA. Applied Geochemistry 10:285–306. LINDEGAARD, C., AND K.P. BRODERSEN. 1995. Distribution of Chironomidae (Diptera) in the river continuum. LITERATURE CITED Pages 257–271 in P. Cranston, editor, Chironomids: from genes to ecosystems. CSIRO, Melbourne, Aus- ARMITAGE, P.D., AND J.H. BLACKBURN. 1985. Chironomi- tralia. dae in a Pennine stream system receiving mine MAHAN, K.I., T.A. FODERARO, T.L. GARZA, R.M. MARTINEZ, drainage and organic enrichment. Hydrobiologia G.A. MARONEY, M.R. TRIVISONNO, AND E.M. WILL- 121:165–172. GING. 1987. Microwave digestion techniques in the BOWMAN, M.F., AND R.C. BAILEY. 1997. Does taxonomic sequential extraction of calcium, iron, chromium, resolution affect the multivariate description of the maganese, lead and zinc in sediments. Analytical structure of freshwater benthic macroinvertebrate Chemistry 59:938–945. 54 WESTERN NORTH AMERICAN NATURALIST [Volume 60

MCGILL, J.D. 1980. The distribution of Chironomidae TER BRAAK, C.J.F. 1990. Update notes: CANOCO version throughout the River Chew drainage system, Avon, 3.1. Agricultural Mathematics Group, Wageningen, England. Doctoral thesis, University of Bristol, Eng- The Netherlands. land. TER BRAAK, C.J.F., AND I.C. PRENTICE. 1988. A theory of POSTMA, J.F., M. KYED, AND W. A DMIRAAL. 1995. Site spe- gradient analysis. Advances in Ecological Research cific differentiation in metal tolerance in the 18:271–317. Chironomus riparius (Diptera, Chironomidae). Hydro- TOKESHI, M. 1995. Life cycles and population dynamics. biologia 315:159–165. Pages 225–268 in P. Armitage, P.S. Cranston, and ROLINE, R.A. 1988. The effects of heavy metals pollution L.C.V. Pinder, editors, The Chironomidae: biology of the Upper Arkansas River on the distribution of and ecology of non-biting midges. Chapman and Hall, aquatic macroinvertebrates. Hydrobiologia 160:3–8. London. ROLINE, R.A., AND J.R. BOEHMKE. 1981. Heavy metals WARD, A.F., AND D.D. WILLIAMS. 1986. Longitudinal zona- pollution of the Upper Arkansas River, Colorado, tion and food of larval chironomids (Insecta: Diptera) and its effects on the distribution of the aquatic along the course of a river in temperate Canada. macrofauna. Bureau of Reclamation Report REC- Holarctic Ecology 9:48–57. ERC-81-15. WARD, J.V. 1986. Altitudinal zonation in a Rocky Mountain RUSE, L.P. 1995a. Chironomid community structure stream. Archiv für Hydrobiologie Supplement 74: deduced from larvae and pupal exuviae of a chalk 133–199. stream. Hydrobiologia 315:135–142. WATERHOUSE, J.C., AND M.P. FARRELL. 1985. Identifying ______. 1995b. Chironomid emergence from an English pollution related changes in chironomid communi- chalk stream during a three year study. Archiv für ties as a function of taxonomic rank. Canadian Jour- Hydrobiologie 133:223–244. nal of Fisheries and Aquatic Sciences 42:406–413. RUSE, L.P., AND S.J. HERRMANN. 2000. Plecoptera and Tri- WILLIAMS, C.J. 1989. Downstream drift of the larvae of choptera species distribution related to environmen- Chironomidae (Diptera) in the River Chew, S.W. tal characteristics of the metal-polluted Arkansas England. Hydrobiologia 183:59–72. River, Colorado. Western North American Naturalist WILSON, R.S. 1988. A survey of the zinc-polluted River 60:57–65. Nent (Cumbria) and the East and West Allen (North- RUSE, L.P., AND R.S. WILSON. 1984. The monitoring of umberland), England, using chironomid pupal exu- river water quality within the Great Ouse basin using viae. Spixiana Supplement 14:167–174. the chironomid exuvial analysis technique. Water WINNER, R.W., M.W. BOESEL, AND M.P. FARRELL. 1980. Pollution Control 83:116–135. community structure as an index of heavy- SANDOVAL, L., J.C. HERRAEZ, G. STEADMAN, AND K.I. metal pollution in lotic ecosystems. Canadian Jour- MAHAN. 1992. Determination of lead and cadmium nal of Fisheries and Aquatic Sciences 37:647–655. in sediment slurries by ETA-AAS: a comparison of YASUNO, M., S. HATAKEYAMA, AND Y. S UGAYA. 1985. Char- methods for the preparation and analysis of sedi- acteristic distribution of chironomids in the rivers ment slurries. Mikrochimica Acta 108:19–27. polluted with heavy metals. Verhandlung der Inter- SOKAL, R.R., AND F. J . R OHLF. 1981. Biometry. Freeman, nationalen Vereinigung für Limnologie 22:2371–2377. New York. SUBLETTE, J.E., L.E. STEVENS, AND J.P. SHANNON. 1998. Received 28 September 1998 Chironomidae (Diptera) of the Colorado River, Grand Accepted 8 February 1999 Canyon, Arizona, USA, Ι: systematics and ecology. Great Basin Naturalist 58:97–146. THIENEMANN, A. 1910. Das Sammeln von Puppenhäuten der Chironomiden. Archiv für Hydrobiolgie 6: 213–214. 2000] CHIRONOMID DISTRIBUTION IN THE ARKANSAS RIVER 55

APPENDIX. Species found at only 1 site, either as pupal exuviae or adults. Listed in alphabetical order within tribes. Species name Pupa/Adult Site Derotanypus alaskensis (Malloch) A AR3 Psectrotanypus dyari (Coquillet) A AR7 Radotanypus submarginella (Sublette) A AR11 Ablabesmyia basalis (Walley) A AR7 Ablabesmyia monilis (Linneaus) A AR11 Ablabesmyia sp. A AR2 Conchapelopia pallens (Coquillet) P AR18 Pentaneura inconspicua (Malloch) A AR18 Telopelopia okoboji (Walley) A AR18 Thienemannimyia barberi (Coquillet) A AR18 Thienemannimyia senata (Walley) A AR18 Zavrelimyia sp. 1-P P AR4 Procladius prolongatus Roback A AR11 Procladius ruris Roback A AR7 Tanypus neopunctipennis Sublette A AR18 Tanypus nubifer Coquillet A AR18 Tanypus stellatus Coquillet A AR18 Diamesa garretti Sublette & Sublette A AR12 Prodiamesa olivacea (Meigen) A AR2 Cardiocladius n. sp. 2 A AR14 Cricotopus intersectus (Staeger) A AR19 Cricotopus lestralis (Edwards) A AR6 Cricotopus sylvestris (Fabricius) P AR12 Cricotopus tricinctus (Meigen) A AR5 Cricotopus trifasciatus (Panzer) A AR5 Cricotopus vierriensis Goetghebuer P AR12 Cricotopus n. sp. 18 A AR8 Cricotopus sp. 14-P P AR4 Cricotopus sp. 15-P P AR2 Cricotopus sp. 18-P P AR12 Cricotopus sp. 20-P P AR11 Cricotopus sp. 21-P P AR20 Eukiefferiella brevineris (Malloch) A AR4 Eukiefferiella n. sp. 4 P AR11 Eukiefferiella n. sp. 8 A AR9 Eukiefferiella sp. 10-P P AR17 Heterotrissocladius sp. A AR7 Nanocladius anderseni Saether A AR17 Nanocladius distinctus (Malloch) A AR17 Nanocladius rectinervis (Kieffer) A AR15 Orthocladius anteilis (Roback) A AR15 Orthocladius appersoni Soponis A AR15 Orthocladius carlatus (Roback) A AR11 Orthocladius dorenus (Roback) A AR1 Orthocladius holsatus Goet A AR2 Orthocladius nanseni Kieffer P AR11 Orthocladius trigonolabis Edwards P AR5 Orthocladius sp. 13-P P AR19 Paracladius conversus (Walker) P EF1 Paratrichocladius skirwithensis (Edwards) A EF1 Psectrocladius vernalis (Malloch) A AR16 Rheocricotopus chapmani (Edwards) A AR11 Metriocnemus n. sp. 2 A AR6 Metriocnemus n. sp. 5 A AR11 Limnophyes hastulatus Saether A AR2 Corynoneura sp. 2-P P AR1 Lopescladius hyporheicus Coffman & Roback A AR16 Parakiefferiella subaterrima (Malloch) P/A EF1/AR20 Paraphaenocladius exagitans (Johannsen) A AR11 Paraphaenocladius tonsuratus Saether & Wang A AR5 Smittia polaris (Kieffer) A AR8 Smittia n. sp. 2 A EF1 Rheosmittia sp. 1-P P AR1 56 WESTERN NORTH AMERICAN NATURALIST [Volume 60

Thienemanniella similis (Malloch) P AR1 Thienemanniella xena (Roback) A AR18 Thienemanniella n. sp. 2 P/A AR16/AR17 Thienemanniella sp. 6-P P AR11 Chironomus stigmaterus Say A AR20 Chironomus n. sp. 5 A AR20 Chironomus n. sp. 8 A AR12 Cladopelma sp. 4-P P AR6 fulvus (Johannsen) A AR18 Cryptochironomus sp. P AR17 casuaria (Townes) A AR11 Cryptotendipes sp. 2-P P EF1 Cyphomella gibbera Saether A AR18 Demicryptochironomus (irmaki) n. sp. 1 A AR18 Dicrotendipes crypticus Epler A AR18 Dicrotendipes lobiger (Kieffer) A AR2 Dicrotendipes modestus (Say) A AR18 sp. A AR19 Microtendipes caelum Townes A AR11 babiyi (Rempel) A AR14 abortivus (Malloch) A AR18 Parachironomus arcuatus (Goetghebuer) A AR18 Parachironomus directus (Dendy & Sublette) A AR19 Parachironomus tenuicaudatus (Malloch) A AR19 Paracladopelma undine (Townes) A AR11 Paracladopelma n. sp. 2 P AR17 Paracladopelma sp. 4-P P AR6 fuscitibia Sublette A AR7 Paratendipes subequalis (Malloch) A AR6 Paratendipes thermophilus Townes P AR17 Polypedilum artifer (Curran) A EF1 Polypedilum fuscipenne (Meigen) A AR12 Polypedilum illinoense (Malloch) P/A AR18/AR18 Polypedilum pedatum Townes A AR12 Polypedilum scalaenum (Schrank) P AR16 Polypedilum sp. 2-P P AR18 Polypedilum sp. 8-P P AR18 Polypedilum sp. 9-P P AR17 Stictochironomus varius (Townes) A AR19 Pseudochironomus rex Hauber A AR12 claviger (Townes) P/A AR17/AR18 Stictochironomus annulicrus (Townes) A AR2 Stictochironomus n. sp. 1 P/A AR18/AR18 Pseudochironomus pseudoviridis (Malloch) A AR18 Cladotanytarsus n. sp. 2 A AR6 Cladotanytarsus n. sp. 3 A AR2 Cladotanytarsus sp. 3-P P AR2 Micropsectra logani (Johannsen) P AR6 Micropsectra nigripila (Johannsen) P AR11 Micropsectra n. sp. 3 A AR4 Micropsectra n. sp. 5 A AR2 Micropsectra n. sp. 6 A EF1 Paratanytarsus dubius (Malloch) A AR12 Paratanytarsus similatus (Malloch) A AR11 Paratanytarsus tenuis (Meigen) A AR11 Paratanytarsus n. sp. 1 A AR7 Stempellinella sp. 1-P P AR12 Sublettea coffmani (Roback) A AR1 Tanytarsus bathophilus Kieffer A AR11 Tanytarsus fimbriatus Reiss & Fittkau A AR11 Tanytarsus pallidicornis (Walker) A AR12 Tanytarsus n. sp. 1 A AR20 Tanytarsus n. sp. 6 P AR12 Tanytarsus n. sp. 13 A AR7 Tanytarsus sp. 2-P P AR6