Aquatic Hemiptera of the Prairie Grasslands and Parkland€¦ · Aquatic Hemiptera of the Prairie...

Scudder, G. G. E., M. A. Alperyn, and R. E. Roughley. 2010. Aquatic Hemiptera of the Prairie Grasslands and Parkland. In Arthropods of Canadian Grasslands (Volume 1): Ecology and Interactions in Grassland Habitats. Edited by J. D. Shorthouse and K. D. Floate. Biological Survey of Canada. pp. 303-323. © 2010 Biological Survey of Canada. ISBN 978-0-9689321-4-8 doi:10.3752/9780968932148.ch14

Chapter 14Aquatic Hemiptera of the

Prairie Grasslands and Parkland

Geoffrey G. E. ScudderDepartment of Zoology, University of British Columbia

Vancouver, British Columbia, Canada V6T 1Z4

Michael A. Alperyn and Robert E. Roughley1

Department of Entomology, University of Manitoba Winnipeg, Manitoba, Canada R3T 2N2

Abstract. Of the 56 species of aquatic Hemiptera in the prairie provinces, 51 occur in the grassland and parkland areas. The majority are represented by lentic species that are ecological generalists, able to adapt to the loss of wetland habitats by utilizing man-made dugouts. Most lentic species are not confined to the Prairies Ecozone, but occur also in forested regions to the north. A few species of aquatic Hemiptera are restricted to lotic or saline habitats. These species seem to have narrower ecological niches and could be affected by loss of these habitat types in the prairies.

Résumé. Cinquante et une des 56 espèces d’hémiptères aquatiques des provinces des Prairies se trouvent dans la prairie et dans la forêts-parc. Il s’agit en majorité d’espèces lentiques, généralistes au plan écologique, et capables de s’adapter à la disparition des habitats humides en utilisant des mares artificielles. La plupart des espèces lentiques ne se limitent pas à l’écozone des prairies, mais se trouvent également dans les régions boisées du nord. Quelques espèces d’hémiptères aquatiques sont limitées aux habitats lotiques ou salés. Ces espèces semblent dépendre de niches écologiques plus restreintes et pourraient souffrir de la disparition de ces types d’habitats dans les prairies.

Introduction

Two distinct vegetation zones are recognized in the Prairies Ecozone (Fig. 1A), namely, an aspen parkland zone with fescue grasses to the north, and a tall, mixed, and shortgrass prairie grasslands zone to the south (Scudder 1979; Ecological Stratification Working Group 1996). These two vegetation zones coincide with distinct limnological regions or wetland subregions (Northcote and Larkin 1963; National Wetlands Working Group (NWWG) 1988). The Grassland Continental Prairie Wetland Subregion (Fig. 1C), as defined by the NWWG (1988), coincides with the prairie limnological region (Fig. 1B) of Northcote and Larkin (1963) and the grassland ecoregions of the Prairies Ecozone (Fig. 1A) (see also Chapters 2 and 3). The Aspen Parkland Continental Prairie Wetland Subregion (Fig. 1C), as depicted by the NWWG (1988), is the same as the saline lakes limnological region (Fig. 1B) of Northcote and Larkin (1963) and the Aspen Parkland, Lake Manitoba Plain, and Southwest Manitoba Uplands ecoregions of the Prairies Ecozone (Fig. 1A).

A third limnological region on the prairies, namely, the forest zone of freshwater lakes (Fig. 1B), extends east and north of the Grassland Continental Prairie Wetland

1 Deceased.

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304 G. G. E. Scudder, M. A. Alperyn, and R. E. Roughley

and the Aspen Parkland Continental Prairie Wetland subregions. This forested region coincides with the Boreal Plains Ecozone (Fig. 1A). To the extreme north is a fourth limnological region, the Northern Lakes zone (Fig. 1B), which coincides with the Boreal Shield Ecozone (Fig. 1A).

The grassland zone, or the Grassland Continental Prairie Wetland Subregion (NWWG 1988), is the true prairie zone, with few large natural lake basins, many small sloughs and reservoirs, and often severe winter stagnation because of autumn drawdown (Northcote and Larkin 1963). Major endorheic drainage systems are present in both the parkland and grassland zones (Hammer 1986a, 1986c), with the saline water bodies in the grassland zone often having over 13,500 ppm of sodium (drinking water usually has 250 ppm or less) (Rawson and Moore 1944). However, the aspen parkland, termed the Aspen Parkland Continental Prairie Wetland Subregion by the NWWG (1988), is the zone of saline lakes with the highest salinity (Rawson and Moore 1944) and high-productivity waters that have a mineral content between 500 and 120,000 ppm (Northcote and Larkin 1963). Hypersaline lakes in this zone can have a salinity as high as 370,000 ppm (Hammer 1978).

The distribution of saline lakes is usually associated with dry climates (see Chapter 2), where evaporation exceeds precipitation (Hammer 1986b). Saline lakes tend to be closed lakes fed principally by surface inflow via general runoff and small streams and through direct precipitation (Hammer 1986b). Few saline lakes occur in the open prairie grassland because this area has relatively few large basins capable of accommodating large lakes, and most of the lakes originally in this vegetation region have dried up (Rawson and Moore 1944). The numerous shallow sloughs can be quite saline, but many of them have been drained.

Fig. 1. Ecological regions in the prairie provinces. A, Terrestrial ecozones and ecoregions. Redrawn after Ecological Stratification Working Group (1996). B, Limnological regions. Redrawn after Northcote and Larkin (1963). C, Wetland subregions. Redrawn after National Wetlands Working Group (1988).

1A

Aquatic Hemiptera of the Prairie Grasslands and Parkland 305

1B

1C


To date, 56 species of aquatic Hemiptera have been reported from the prairie provinces (Maw et al. 2000).1 Seven of these species (Belostoma flumineum Say, Buenoa margaritacea Torre-Bueno, Lethocerus griseus (Say), Nepa apiculata Uhler, Neoplea striola (Fieber), Notonecta insulata Kirby, and Ranatra fusca Palisot) are confined to the Boreal Plains and Boreal Shield ecozones in the southeast corner of Manitoba. Two further species (Arctocorisa chanceae Hungerford, Callicorixa producta noorvikensis Hung.) occur only in the Northern Lakes zone in this province. Thus, 47 species occur in the prairie grassland and parkland ecoregions, although 51 species occur in grassland and parkland areas. Rawson and Moore (1944) noted that the aquatic Hemiptera as a group are very tolerant of salinity, which has been confirmed by subsequent studies (Scudder 1976; Hammer 1986b). In the British Columbia interior, increased salinity is accompanied by a significant decrease in richness of corixids and a trend for increased densities (Lancaster and Scudder 1987), and the same trends are evident on the prairies (Tones 1976). However, the studies in the Prairies Ecozone (Rawson and Moore 1944; Tones 1976) have concentrated on the aquatic Hemiptera in saline water bodies in the aspen parkland zone, comparing species richness with lakes in the forest zone, where water bodies are predominantly eutrophic or mesotrophic, with mineral content in the 200–500 ppm range (Northcote and Larkin 1963). Little comparative study has been done of the aquatic fauna of water bodies in the prairie grasslands zone. The account herein attempts to correct this void.

Water Bodies Sampled

Water bodies were sampled by Alperyn and Roughley in 2003 across the southern parts of Alberta, Saskatchewan, and Manitoba (Fig. 2). Most of these localities were in the prairie grasslands zone, but a few were sampled in the Boreal Plains and Boreal Shield ecozones in the southeast corner of Manitoba, as well as in the parkland zone of this province. The geographical coordinates of sample sites were recorded by means of a global positioning system (Garmin Model 12XL). A Hanna Instruments Model 9812 portable pH meter was used to measure pH, and conductivity was measured with a Bach-Simpson Model Conductivity Meter.

The localities sampled (Tables 1 and 2) were assigned to a wetland region or subregion by reference to the geographical position of the particular site, with forested regions identified by reference to A National Ecological Framework for Canada (Ecological Stratification Working Group 1996) and cross-checked via images of each habitat. These images were taken with a digital camera (Nikon Coolpix model 995), with images of most localities subsequently stored on the website of the University of Manitoba J.B. Wallis Museum of Entomology.

Samples of aquatic Hemiptera were obtained by use of a standard D frame aquatic net with a triangular frame and maximum width of 12 inches (= 30.5 cm) (BioQuip Products model 741D). We obtained the samples by sweeping vigorously while walking parallel to the shoreline within the littoral zone of the water bodies for a set period of time, typically 10–20 minutes. All specimens were preserved in 70% ethanol and later processed at the University of British Columbia.

1 Sigara signata (Fieber), recorded from Manitoba by Polhemus et al. (1988) and Maw et al. (2000), is omitted because no authentic record can be traced. However, Notonecta spinosa Hung. is added following its collection in Waterton Lakes National Park (Scudder 2008).


For most samples, all adult specimens were mounted and labelled. For samples with very large numbers of Trichocorixa, all specimens were examined in alcohol, the numbers estimated, and a representative sample of the Trichocorixa species mounted and labelled. All other waterbugs in such samples were mounted and labelled.

Scudder identified specimens by using a Bausch & Lomb (×30) dissecting microscope. Adults were identified from keys in Brooks and Kelton (1967). Species of Cenocorixa were named by means of the key in Jansson (1972). Hungerford (1948), Stonedahl and Lattin (1986), Tinerella and Gundersen (2005), and named reference material in the Canadian National Collection, as well as in the Scudder Collection, aided in the identification of the Corixidae. Voucher material is deposited in the J.B. Wallis Museum of Entomology at the University of Manitoba; the Canadian National Collection of Insects, Arachnids, and Nematodes at Agriculture and Agri-Food Canada in Ottawa; and Scudder’s own collection. Voucher material for many species collected in Alberta was also deposited in the E.H. Strickland Entomological Museum at the University of Alberta, Edmonton. Voucher material for many species collected in Saskatchewan was deposited in the Royal Saskatchewan Museum, Regina. Vouchers of a few species were also deposited in the Spencer Entomological Collection in the Beaty Biodiversity Museum at the University of British Columbia, Vancouver.

Sampling in 2003 did not cover the full range of salinities present in the saline lakes in the prairie grasslands; thus, data from other studies (Rawson and Moore 1944; Brooks and Kelton 1967; Tones 1976) were obtained to fill in such gaps.

Twenty-six (60.5%) of the 43 main water bodies sampled were in the Grassland Continental Prairie Wetland Subregion, eight (18.6%) in the Aspen Parkland Continental Prairie Wetland Subregion, and nine (21%) in forested regions (Table 1). The water bodies in the latter zones had the lowest conductivities, namely, 243–545 μS/cm, with pH between 7.7 and 8.5. The Aspen Parkland Continental Prairie Wetland Subregion water bodies

Fig. 2. Location of water bodies sampled. • = Main water bodies, included in Tables 1 and 3; o = additional water bodies, included in Tables 2 and 4. Note: Two other water bodies sampled and mentioned in Table 5 footnotes are not included.

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Table 1. Main water bodies sampled in 2003, arranged in order of decreasing conductivity.

Lake No.

Locality Site Description Wetland Region or Subregion1

Latitude Longitude pH2 Conductivity (µS/cm)2

Time Date Sampled

Collector3

1 SK, Hwy. 1, 2 km E. Swift Current

31 Saline pond G 50°20′15.0″ 107°41′17.6″ 8.4 29,000 <10 min.

1 Sept. 2003 MA

2 SK, Channel Lake, Hwy. 3

6 Saline pond G 49°32′28.7″ 105°13′50.6″ 8.9 20,000 24 min. 26 Aug. 2003

MA

3 SK, 5 km W., Swift Current, Hwy. 2


MA

4 SK, Morse, Reed L. 32 Saline lake margin

G 50°25′16.5″ 107°06′02.7″ 8.9 16,000 15 min. 1 Sept. 2003 MA

5 SK, Snake Cr. At Hwy. 4, N. Val. Marie, nr. Grassland Nat. Pk.

10 Embayment of stream, functioning as lentic pond

G 49°14′ 107°44″ 8 13,600 11 min. 26 Aug. 2003

MA

6 SK, Webb, Hwy. 1 at Rd. 171

30 Saline pond G 50°11′36.3″ 108°12′42.4″ 8 13,600 <20 min.

1 Sept. 2003 MA

7 SK, 3 km E. Parkbeg 33 Typha pond G 50°27′20.8″ 106°12′09.6″ 7.9 11,200 <5 min. 1 Sept. 2003 MA

8 MB, 5 km N. Baldur, Hwy. 245, Cobbe’s L., E. side of Hwy. 245

12We Saline lake margin

P 49°25′30.7″ 99°14′51.3″ 9.1† 9,500† ca 15 min.

16 May 2003

MA & RER

MB, 5 km N. Baldur, Hwy. 245, Cobbe’s L., E. side of Hwy. 245

12We Saline lake P 49°25′30.7″ 99°14′51.3″ 24 min. 25 Sept. 2003

MA

9 SK, Gull L., W. side Hwy. 37

14 Dugout G 50°06′51.7″ 108°29′05.0″ 6.8 6,600 10 min. 28 Aug. 2003

MA

10 SK, Cypress Hills Inter Pr. Pk., Centre Block, Loch Lomand

17 Forested lake P* 49°39′37.8″ 109°30′04.4″ 7.2 6,600 <20 min.

29 Aug. 2003

MA

A

quatic Hem

iptera of the Prairie G

rasslands and Parkland

309

11 SK, 1.5 km E. Coronach, Hwy. 18

7 Dugout, with Typha margin

G 49°06′52.2″ 105°30′0.00″ 6.8 6,500 26 min. 27 Aug. 2003

MA

12 MB, 5 km N. Baldur, Hwy. 245, Cobbe’s L., W side of Hwy. 245

12Ww Saline lake margin

P 49°25′44.7″ 99°15′18.6″ 8.7† 6,075† <20 min.

15 May 2003

MA & RER

MB, 5 km N. Baldur, Hwy. 245, Cobbe’s L., W side of Hwy. 245


P 49°25′44.7″ 99°15′18.6″ 14 min. 25 Sept. 2003

MA

13 MB, 6 km N. Baldur, Hwy. 245, Taylor’s L., W side on Hwy. 245


P 49°26′24.3" 99°14′49.5″ 8.7 3,250 ca 20 min.

30 June 2003

MA & RER

MB, 6 km N. Baldur, Hwy. 245, Taylor’s L., W side on Hwy. 245


P 49°26′24.3″ 99°14′49.5″ 18 min. 25 Sept. 2003

MA

14 MB, 6 km N. Baldur, Hwy. 245, Taylor’s L.

13We Saline lake margin

P 49°26′24.1″ 99°14′48.8″ 8.8 1,990 ca 20 min.

30 June 2003

MA & RER

15 SK, Thomson L. Reg. Pk., Hwy. 58 betw. Gravelbourg & LaFlech


MA

16 AB, Lundbreck 27 Dugout G 49°35′05.3″ 114°07′36.5″ 9.8 1,750 <20 min.

31 Aug. 2003

MA

17 SK, Outside Cypress Hills, Inter. Pr. Pk., Centre Block, Gap Rd.

15 Temporary prairie pond

G 49°36′58.3″ 109°43′42.1″ 9.3 1,450 <20 min.

29 Aug. 2003

MA

18 SK, Stoughton, Hwy. 13

3 Prairie pond G 49°40′05.7″ 103°13′05.6″ 7.1 1,400 14 min. 26 Aug. 2003

MA

19 AB, Hwy. 501, 5 km W SK-AB border

18 Dugout G 49°12′40.2″ 110°08′18.0″ 9.8 1,400 <20 min.

29 Aug. 2003

MA

20 SK, 1 km E Pangman, Hwy. 13

5 Prairie pond G 49°38′20.9″ 104°38′45.6″ 7 1,260 16 min. 26 Aug. 2003

MA

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Lake No.


Latitude Longitude pH2 Conductivity (µS/cm)2

Time Date Sampled

Collector3

21 MB, 8 km N. Baldur, Hwy. 245

14w Large pond P 49°27′45.8″ 99°14′43.9″ 8.9 1,218 20 min. 25 Sept. 2003

MA

22 MB, Linklater 103 Prairie pond with Typha margin

P 49°36′38.5″ 101°12′49.4″ 9.1 1,114 16 min. 26 Aug. 2003

MA

23 AB, Hwy. 61, 2 km W Judson

22 Ditch G 49°31′25.6″ 112°20′42.5″ 8.6 920 6 min. 29 Aug. 2003

MA

24 AB, Chokio 24 Water retention pond

G 49°33′16.5″ 113°43′56.9″ 9.3 900 6 min. 30 Aug. 2003

MA

25 SK, 2 km W. Assiniboia, Hwy. 13

8 Temporary pond with Salicornia

G 49°38′24.9″ 106°03′26.5″ 7.7 880 15 min. 27 Aug. 2003

MA

26 SK, 2.5 km E Belle Plain

34 Typha pond G 50°23′47.8″ 105°11′48.2″ 8.7 840 <10 min.

1 Sept. 2003 MA

27 AB, Pincher Creek at Hwy. 3

25 Dugout G 49°33′16.5″ 113°43′56.9″ 9.1 700 5 min. 30 Aug. 2003

MA

28 SK, 21 km E. Climax, Hwy. 18

11 Pond G 49°11′36.8″ 108°8′58.2″ 6.5 580 11 min. 26 Aug. 2003

MA

29 AB, Foremost, 10 km W. on Hwy. 61

20 Temporary prairie pond

G 49°29′24.4″ 111°39′12.1″ 7.1 580 11 min. 29 Aug. 2003

MA

30 SK, Cypress Hills Inter. Pr. Pk. Centre Block

16 Boreal pond P* 49°39′27.4″ 109°29′29.1″ 6.9 570 <20 min.

29 Aug. 2003

MA

31 AB, Hwy. 6 nr. Twin Butte, 7 km S. of Hwy. 505

28 Dugout G 49°16′09.5″ 113°51′33.6″ 8.9 550 <10 min.

31 Aug. 2003

MA

32 MB, Prawda, Hwy. 1 8E Dugout with Typha margin

F (BS)

49°38′48.5″ 95°45′51.4″ 7.8 545 >20 min.

8 May 2003 MA

33 SK, Weyburn, Hwy. 13

4 Prairie pond G 49°40′05.5″ 104°04′27.5″ 7 470 <15 min.

26 Aug. 2003

MA

Table 1 (continued)

A

quatic Hem



311

34 AB, Lethbridge, 17 km W. on Hwy. 3

23 Typha pond G 49°47′14.3″ 113°02′44.5″ 7.9 430 7 min. 30 Aug. 2003

MA


F (BS)

49°38′48.1″ 95°44′48.8″ 8 343 >20 min.

8 May 2003 MA


F (BS)

49°38′50.9″ 95°45′32.7″ 8.1 338 >20 min.

8 May 2003 MA

MB, Prawda, Hwy. 1 12E Dugout with Typha margin

F (BS)

49°38′50.9″ 95°45′32.7″ 15 min. 22 July 2003

MA & RER

37 MB, Falcon L., alongside Hwy. 1

16E Dugout with Typha margin

F (BS)

49°38′05.8″ 95°31′17.7″ 8.4 331 >20 min.

8 May 2003 MA

MB, Falcon L., alongside Hwy. 1


F (BS)

49°38′05.8″ 95°31′17.7″ ca 10 min.

22 June 2003

MA & RER


F (BS)

49°38′50.8″ 95°45′33.4″ 8.3 324 ca 16 min.

22 June 2003

MA & RER

39 AB, Hwy. 61, 1 km E. Skift

21 Dugout G 49°24′38.5″ 111°45′24.1 6.6 320 <20 min.

29 Aug. 2003

MA

40 MB, Reynold’s Pond, Hwy. 1


F (BP)

49°43′43.7″ 96°16′02.4″ 8† 318† >20 min.

8 May 2003 MA

41 MB, Richer, pond nr. Reynold’s Pond


F (BP)

49°43′28.4″ 95°15′35.9″ 8.3† 286† >20 min.

8 May 2003 MA

MB, Richer, pond nr. Reynold’s Pond


F (BP)

49°43′28.4″ 95°15′35.9″ ca 12 min.

22 June 2003

MA & RER

42 MB, Richer, pond nr. Reynold’s Pond


F (BP)

49°43′01.9″ 96°14′25.9″ 7.7† 255† >20 min.

8 May 2003 MA

MB, Richer, pond nr. Reynold’s Pond


F (BP)

49°43′01.9″ 96°14′25.9″ ca 8 min.

22 June 2003

MA & RER

43 MB, Falcon L., Hwy. 1


F (BS)

49°38′12.6″ 95°27′33.3 8.5 243 >20 min.

8 May 2003 MA

1 G = Grassland Continental Prairie Wetland Subregion; P = Aspen Parkland Continental Prairie Wetland Subregion; P* = forested vegetation in Aspen Parkland Continental Prairie Wetland Subregion; F(BS) = Northern Lakes forest in Boreal Shield Ecozone; F(BP) = forest region in Boreal Plains Ecozone.

2 † = Data as an average of monthly readings May–Sept. 2001.3 MA = M. Alperyn; RER = R.E. Roughley.

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Table 2. Seven additional water bodies studied in 2003.

Lake No.


Latitude Longitude Time Date Sampled

Collector2

44 AB, Crowsnest R., Lundbreck Falls Prov. Recr. Area

26 Lotic G 49º35′03.8″ 114º12′18.0″ <20 min. 30 Aug. 2003 MA

45 AB, Dungaroon Cr. at Hwy. 6 between Twinn Butte & Park Union

29 Lotic G 49º33′16.5″ 113º43′56.9″ <10 min. 31 Aug. 2003 MA

46 AB, Manyberries, 4 km W

19 Dugout G 49º23′57.8″ 110º47′04.9″ <20 min. 29 Aug. 2003 MA

47 SK, Channel Lakes - Saline lake G 49º32′29″ 103º13′47″ 16 July 2003 RER

48 SK, Little Kenosee L., Moose Mt. Prov. Park

2 Shallow lake (with Scirpus and dense aquatic vegetation around perimeter)

P 49º52′05.3″ 102º16′39.4″ 20 min. 26 Aug. 2003 MA

49 SK, Moose Mt. Prov. Park

1 Boreal pond P 49º52′05.3 102º16′39.4″ 19 min. 26 Aug. 2003 MA

50 SK, S. end Willow Bunch Lake, nr. Harptree

- Drying isolated stream bed

G 49º09′36″ 105º20′05″ 20 min. 16 July 2003 RER

1 G = Grassland Continental Prairie Wetland Subregion; P = Aspen Parkland Continental Prairie Wetland Subregion.2 MA = M. Alperyn; RER = R.E. Roughley.


were more saline, with conductivities between 1,114 and 9,500 μS/cm, and pH 8.8–9.1. Conductivities of water bodies sampled in the Grassland Continental Prairie Wetland Subregion varied, from 320 to 29,000 μS/cm, with pH from 6.6 to 9.3.

Seven additional prairie water bodies were sampled in 2003 (Table 2), for which pH and conductivity data are not available: most were in the Grassland Continental Prairie Wetland Subregion. Two other water bodies in forested regions were also sampled in 2003 (Table 5 footnotes).

A wide variety of water body types were sampled in this research, including boreal marsh, boreal pond, ditch, drying isolated stream bed, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, forested lake, large pond, pond, prairie pond, prairie pond with Typha margins, saline lake, saline pond, shallow lake (with Scirpus and dense aquatic vegetation around perimeter), temporary pond with Salicornia, temporary prairie pond, Typha pond, or water retention pond. We sampled only two lotic habitats (Table 2).

Species Found at the Sampling Sites

Thirty-six aquatic Hemiptera species were collected in the main series of samples in 2003 (Table 3). Two further species (Callicorixa alaskensis Hungerford and Sigara washingtonensis Hungerford) were collected in the additional water bodies sampled (Tables 4 and 5). These 38 species constitute 67.9% of the 56 species of aquatic Hemiptera reported from the prairie provinces, and 74.5% of the 51 species reported from the Continental Prairie Wetland subregions.

Twenty-five species were collected in water bodies sampled in 2003 in the Grassland Continental Prairie Wetland Subregion and 19 species in the Aspen Parkland Continental Prairie Wetland Subregion (Table 6). Three of the species recorded in 2003 (Belostoma flumineum, Ranatra fusca, and Neoplea striola (Fieber)) were found only in forested zones, as they are confined in the prairie provinces to the Boreal Plains or Boreal Shield ecozones in southeast Manitoba. However, four other more widely distributed species (Hesperocorixa michiganensis (Hungerford), Sigara mulletensis (Hungerford), S. penniensis (Hungerford), and S. trilineata (Provancher)) were also found only in these forested regions. Lethocerus americanus (Leidy) was collected in both forested and parkland water bodies. Callicorixa alaskensis was collected only in a boreal marsh near Grimshaw, Alberta (Table 5).

The commonest species collected, namely, those that occurred in the largest number of water bodies sampled, were the corixids Cenocorixa bifida bifida (Hungerford) (32 locations) and Hesperocorixa laevigata (Uhler) (28 locations) and the notonectid Notonecta undulata Say (30 locations) (Tables 3 and 4). These three species are ecological generalists and occurred in a wide variety of water bodies (Table 5).

Seven species (Buenoa margaritacea, Callicorixa alaskensis, Hesperocorixa michiganensis, Sigara grossolineata Hungerford, S. lineata (Forster), S. trilineata, and S. washingtonensis) were each found in just one location (Tables 3–5) in low abundance, and they differed in the locality and water body type (Table 5). Sigara washingtonensis occurred only in a lotic habitat.

Altogether, 25 species were collected in dugouts or dugouts with a Typha margin, whereas 19 species were found in prairie ponds or prairie ponds with a Typha margin (Table 5). Saline lakes and saline ponds had a diverse assemblage of 18 species of waterbugs, with just two species, Cenocorixa expleta (Uhler) and Dasycorixa rawsoni Hungerford, confined to such habitats (Table 5). Although Trichocorixa verticalis interiores Sailer was not confined to such saline waters, when it did occur in saline lakes, it was at times exceedingly abundant.

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Table 3. Occurrence of species of aquatic Hemiptera in main water bodies sampled in 2003. Lakes numbered as in Table 1. Abbreviations: G = Grassland Continental Prairie Wetland Subregion; P = Aspen Parkland Continental Prairie Wetland Subregion; F = forested areas; x = 10 or fewer specimens; o = 11–100 specimens; # = over 100 specimens.

Lak

e N

o.

Con

duct

ivit

y (µ

S/cm

)

Wet

land

Reg

ion

or S

ubre

gion

BE

LO

STO

MA

TID

AE

Bel

osto

ma

flum

ineu

m (S

ay)

Leth

ocer

us a

mer

ican

us (L

eidy

)C

OR

IXID

AE

Cal

licor

ixa

aude

ni H

u R

efer

ence

s (H

unge

rfor

d)

Cen

ocor

ixa

bifid

a bi

fida

(Hun

gerf

ord)

C. d

akot

ensi

s (H

unge

rfor

d)

C. e

xple

ta (U

hler

)

C. u

tahe

nsis

(Hun

gerf

ord)

Cor

isel

la ta

rsal

is (F

iebe

r)

Cym

atia

am

eric

ana

Hus

sey

Das

ycor

ixa

raw

soni

Hun

gerf

ord

Hes

pero

cori

xa a

topo

dont

a (H

unge

rfor

d)

H. l

aevi

gata

(Uhl

er)

H. m

ichi

gane

nsis

(Hun

gerf

ord)

H. v

ulga

ris

(Hun

gerf

ord)

Siga

ra a

ltern

ata

(Say

)

S. b

icol

orip

enni

s (W

alle

y)

S. c

onoc

epha

la (H

unge

rfor

d)

S. d

ecor

ata

(Abb

ott)

S. d

ecor

atel

la (H

unge

rfor

d)

S. g

ross

olin

eata

Hun

gerf

ord

S. li

neat

a (F

orst

er)

S. m

athe

soni

(Hun

gerf

ord)

S. m

ulle

ttens

is (H

unge

rfor

d)

S. p

enni

ensi

s (H

unge

rfor

d)

S. s

olen

sis

(Hun

gerf

ord)

S. tr

iline

ata

(Pro

vanc

her)

Tric

hoco

rixa

bor

ealis

Sai

ler

T. s

exci

ncta

(Cha

mpi

on)

T. v

ertic

alis

inte

rior

es S

aile

r

NE

PID

AE

Ran

atra

fusc

a Pa

lisot

NO

TO

NE

CT

IDA

EB

ueno

a m

acro

tibia

lis H

unge

rfor

d

B. m

arga

rita

cea

Torr

e B

ueno

Not

onec

ta b

orea

lis H

usse

y

N. k

irby

i Hun

gerf

ord

N. u

ndul

ata

Say

PL

EID

AE

Neo

plea

str

iola

(Fie

ber)

1 29,000 G x o x x x o o

2 20,000 G x o o x o x x x o x

3 16,700 G o x x x x o x x o x

4 16,000 G x o o x # x

5 13,600 G x o x o o x x x x x x x # x x

6 13,600 G x x x o x o x x x x

7 11,200 G o x x x o

8 9,500 P x o o x o x x x x #

9 6,600 G x x o x x o x x x x

10 6,600 P x x x x o o o x

11 6,500 G x o x o o x x o x

12 6,075 P x o o x x x # x

13 3,250 P x o o x x x x x o o o o x x

A

quatic Hem



315

14 1,990 P x x x x x x x

15 1,800 G x o x x x x x x x x

16 1,750 G x x x x

17 1,450 G x o x o o o x x

18 1,400 G # o x o o o o o o x x x x

19 1,400 G o x x o o x x x x x x

20 1,260 G o o x x x x x x x x x x x

21 1,218 P x x x o x x o x x x x

22 1,114 P o x o x x o x x o x

23 920 G x x x o o x x x

24 900 G x x x x

25 880 G o o x x x o o x x

26 840 G x x x x x x x x x

27 700 G x o o x x

28 580 G o o x x

29 580 G o x x o o x x

30 570 P x x x x x o x o

31 550 G o o

32 545 F x x x

33 470 G # x x x o x x x x x x

34 430 G x x x o x x x

35 343 F x x x x x x

36 338 F x x x

37 331 F x x x x

38 324 F x x x

39 320 G # o x x o x x x

40 318 F x x

41 286 F o x x x x x x x

42 255 F x x x x x x x x x

43 243 F x x x x

No. of localities 5 2 21 28 17 4 20 10 15 3 3 26 1 18 22 14 4 2 10 1 2 2 2 2 10 1 4 10 16 6 2 1 1 18 27 3


Significance of Findings

We have chosen to stress the NWWG (1988) terminology for the zones investigated because the aquatic Hemiptera are wetland inhabitants in the grasslands and parkland. Although the main water bodies sampled had conductivities ranging between 324 and 29,000 μS/cm, we did not sample extremely saline lakes because, as noted in the Introduction, we concentrated our sampling on a range of habitats in the Grassland Continental Prairie Wetland Subregion.

Faunal Diversity and Habitat AffinityTwenty-five species of aquatic Hemiptera were collected in the Grassland Continental Prairie Wetland Subregion and 19 species in the Aspen Parkland Continental Prairie Wetland Subregion. However, available records indicate that more species (n = 49) are actually known from the latter than from the former (n = 29). Because most of the water bodies sampled in 2003 were visited only once, some species were likely missed.

Most of the waterbug species in the Continental Prairie Wetland Region (n = 45) are clearly ecological generalists, as they also occur in adjacent forest wetland regions. Of the widely distributed species, only Corisella tarsalis (Fieber) and Trichocorixa sexcincta (Champion) are confined to the Continental Prairie Wetland Region.

Lethocerus griseus (Say), Palmacorixa gillettei Abbott, and Buenoa margaritacea are confined to the Aspen Parkland Continental Prairie Wetland Subregion in the prairie

Table 4. Occurrence of species of aquatic Hemiptera in seven additional water bodies sampled in 2003. Lakes numbered as in Table 2. Abbreviations: x = 10 or fewer specimens; o = 11–100 specimens.

Lak

e N

o.

CO

RIX

IDA

E

Cal

licor

ixa

aude

ni H

unge

rfor

d

Cen

ocor

ixa

bifid

a bi

fida

(Hun

gerf

ord)

C. d

akot

ensi

s (H

unge

rfor

d)

C. u

tahe

nsis

(H

unge

rfor

d)

Cor

isel

la ta

rsal

is (

Fieb

er)

Cym

atia

am

eric

ana

Hus

sey

Hes

pero

cori

xa la

evig

ata

(Uhl

er)

Siga

ra a

ltern

ata

(Say

)

S. b

icol

orip

enni

s (W

alle

y)

S. d

ecor

atel

la (

Hun

gerf

ord)

S. s

olen

sis

(Hun

gerf

ord)

S. w

ashi

ngto

nens

is H

unge

rfor

d

Tric

hoco

rixa

bor

ealis

Sai

ler

T. v

ertic

alis

inte

rior

es S

aile

r

NO

TO

NE

CT

IDA

E

Not

onec

ta b

orea

lis H

usse

y

N. k

irby

i Hun

gerf

ord

N. u

ndul

ata

Say

44 x o

45 x x

46 x x x o o x

47 x o x x x x

48 x x o x x

49 x x x x

50 x x x x x o


provinces (Table 6), but these species are not widely distributed. Likewise, Notonecta spinosa Hungerford, recently collected in a grassland pond and spring-fed Carex marsh in Waterton Lakes National Park (Scudder 2008) is a western species, known previously in Canada only from the Okanagan in British Columbia (Scudder 1977) in the Intermountain Prairie Wetland Region (NWWG 1988).

Seventeen species were collected in prairie ponds or prairie ponds with Typha margin, and an overlapping 18 species were recorded in saline lakes and saline ponds (Table 5); the 21 species so involved constitute the typical Grassland Continental Prairie Wetland Subregion fauna. There are, of course, other species of waterbugs in the lotic water bodies on the prairies. Two of these species, Sigara grossolineata and S. lineata, were found in the embayment of a stream functioning as a lentic pond. Sigara washingtonensis was collected only in a lotic habitat.

Most of the 21 species in the typical waterbug fauna from the Grassland Continental Prairie Wetland Subregion have also been detected in lentic habitats in the grasslands of the Intermountain Prairie Wetland Region (Scudder 1969, 1987; Lancaster and Scudder 1987). Species in the latter region show a clear decrease in species richness with increasing salinity (Scudder 1969, 1987; Lancaster and Scudder 1987), a feature identified as characteristic of the saline lakes zone or Aspen Parkland Continental Prairie Wetland Subregion by Northcote and Larkin (1963). Although not clearly obvious from our sample data from 2003, this phenomenon of decreased species richness with increasing salinity is generally true for waterbugs and other aquatic biota of the Prairies Ecozone (Rawson and Moore 1944; Tones 1976; Hammer 1986b; Timms et al. 1986; Hammer et al. 1990). Although aquatic Hemiptera as a group are very tolerant of salinity (Rawson and Moore 1944), only a few species have the ability to regulate their osmotic and ionic milieu in hyperosmotic waters (Scudder 1976). Scudder et al. (1972) showed that this was possible in Cenocorixa expleta, and Tones and Hammer (1975) demonstrated this also in Trichocorixa verticalis interiores. The same regulatory ability probably exists in Dasycorixa rawsoni and perhaps Corisella tarsalis. Trichocorixa verticalis interiores probably has the best developed osmotic and ionic regulation of all aquatic Hemiptera. It is the only species of waterbug able to live in Little Manitou Lake in Saskatchewan (Tones 1976), where the conductivity can vary from 57,300 to 77,100 μS/cm (Hammer 1978). However, Rawson and Moore (1944) did not find this species in the lake.

This osmotic and ionic regulatory ability limits which species of waterbug can inhabit saline lakes and ponds and limits the extremes that the various saline-tolerant species can withstand. However, it does not limit the ability of these so-called saline waterbugs to live in freshwater habitats. Cannings (1978) reared Cenocorixa expleta in freshwater, and Scudder et al. (1972) showed that this species could hyperregulate its internal milieu in freshwater. Tones and Hammer (1975) showed the same ability in Trichocorixa verticalis interiores, an observation that is confirmed by the fact that this species is not confined to saline lakes and ponds (Table 4). Corisella tarsalis likewise has a broad salinity tolerance, but Cenocorixa expleta and Dasycorixa rawsoni seem to be confined to saline lakes and ponds. Waters with high salinity are evidently enemy-free space (Jeffries and Lawton 1984; Berdegue et al. 1996) such that D. rawsoni may also be excluded from low-salinity water bodies by mite parasitism (Scudder 1983; Bennett and Scudder 1998).

Prairie Wetland ConservationNatural wetland habitats in the prairies have been decimated by human activities. About 70% of North American prairies have been converted to cropland (Dale-Burnett and Anderson


Table 5. Types of water body inhabited by aquatic Hemiptera on the prairies, as detected in samples collected in 2003. Types of water body underlined had 11–100 specimens in sample; types in bold had over 100.

Species Types of Water Body in Which Found

BELOSTOMATIDAE

Belostoma flumineum Say Dugout with Typha margin

Lethocerus americanus (Leidy)

Boreal pond, dugout with Typha margin

Corixidae

Callicorixa alaskensis Hungerford

Boreal marsh1

C. audeni Hungerford Boreal marsh, boreal pond, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, large pond, lotic, prairie pond with Typha margin, prairie pond, saline lake, temporary pond with Salicornia, temporary prairie pond, Typha pond

Cenocorixa bifida bifida (Hungerford)

Ditch, dry isolated stream bed, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, forested lake, prairie pond, saline lake, saline pond, shallow lake (with Scirpus and dense aquatic vegetation around perimeter), temporary pond with Salicornia, temporary prairie pond, Typha pond, water retention pond

Cenocorixa dakotensis (Hungerford)

Dry isolated stream bed, dugout, dugout with Typha margin, large pond, prairie pond, saline lake, saline pond, temporary prairie pond, Typha pond, water retention pond

Cenocorixa expleta (Uhler) Saline pond, saline lake

Cenocorixa utahensis (Hungerford)

Boreal pond, ditch, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, prairie pond, prairie pond with Typha margin, saline lake, saline pond, temporary pond with Salicornia, temporary prairie pond, Typha pond

Corisella tarsalis (Fieber) Ditch, dry isolated stream bed, dugout, dugout with Typha margin, saline pond, temporary pond with Salicornia, temporary prairie pond

Cymatia americana Hussey Dugout, dugout with Typha margin, large pond, prairie pond, prairie pond with Typha margin, saline lake, saline pond, shallow lake (with Scirpus and dense aquatic vegetation around perimeter), Typha pond

Dasycorixa rawsoni Hungerford

Saline lake, saline pond

Hesperocorixa atopodonta (Hungerford)

Boreal pond, prairie pond, prairie pond with Typha margin

H. laevigata (Uhler) Ditch, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, pond, large pond, prairie pond, prairie pond with Typha margin, saline lake, saline pond, temporary pond with Salicornia, temporary prairie pond, Typha pond, water retention pond

H. michiganensis (Hungerford)

Dugout with Typha margin

H. vulgaris (Hungerford) Dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, forested lake, pond, prairie pond, prairie pond with Typha margin, saline pond, temporary pond with Salicornia, temporary prairie pond, Typha pond


Sigara alternata (Say) Boreal pond, ditch, dry isolated stream bed, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, large pond, lotic, pond, prairie pond, prairie pond with Typha margin, saline pond, temporary pond with Salicornia, temporary prairie pond, Typha pond

S. bicoloripennis (Walley) Ditch, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, forested lake, large pond, prairie pond, prairie pond with Typha margin, saline lake, saline pond, shallow lake (with Scirpus and dense aquatic vegetation around perimeter)

S. conocephala (Hungerford)

Dugout with Typha margin

S. decorata (Abbott) Embayment of stream functioning as lentic pond, forested lake

S. decoratella (Hungerford) Boreal pond, dugout with Typha margin, large pond, prairie pond, prairie pond with Typha margin, saline lake, Typha pond

S. grossolineata Hungerford Embayment of stream functioning as lentic pond

S. lineata (Forster) Embayment of stream functioning as lentic pond

S. mathesoni (Hungerford) Boreal pond, forested lake

S. mullettensis (Hungerford) Dugout with Typha margin

S. penniensis (Hungerford) Dugout with Typha margin

S. solensis (Hungerford) Boreal pond, dugout with Typha margin, dry isolated stream bed, embayment of stream functioning as lentic pond, forested lake, prairie pond, saline lake, temporary pond with Salicornia, Typha pond

S. trilineata (Provancher) Dugout with Typha margin

S. washingtonensis Hungerford

Lotic

Trichocorixa borealis Sailer Drying isolated stream bed, dugout, dugout with Typha margin, saline pond

T. sexcincta (Champion) Boreal pond, dugout, embayment of stream functioning as lentic pond, forested lake, large pond, prairie pond, saline pond, temporary pond with Salicornia

T. verticalis interiores Sailer Dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, large pond, prairie pond, saline pond, saline lake, Typha pond

NEPIDAE

Ranatra fusca Palisot Dugout with Typha margin

NOTONECTIDAE

B. macrotibialis Hungerford Saline lake margin

B. margaritacea Torre Bueno

Large pond

Notonecta borealis Hussey Boreal pond, prairie pond, Typha pond2

N. kirbyi Hungerford Boreal pond, ditch, dugout, embayment of stream functioning as lentic pond, forested lake, lotic, prairie pond, saline pond, saline pond, shallow lake (with Scirpus and dense aquatic vegetation around perimeter), temporary prairie pond, Typha pond, water retention pond

N. undulata Say Boreal pond, ditch, dugout, dugout with Typha margin, embayment of stream functioning as lentic pond, large pond, pond, prairie pond, prairie pond with Typha margin, saline lake, saline pond, saline pond, shallow lake (with Scirpus and dense aquatic vegetation around perimeter), temporary prairie pond, Typha pond

PLEIDAE

Neoplea striola (Fieber) Dugout with Typha margin

1 AB, Queen Elizabeth Park, nr. Grimshaw, 56°13′08″N 119°41′34″W, 20 July 2003 (RER).2 SK, Cowan Dam at Hwy. 55, 54°11′49″N 107°27′W, 22 July 2003 (RER).

Table 5 (continued)


Table 6. Distribution of the aquatic Hemiptera of the Prairie Wetland subregions. Abbreviations: G = Grassland Continental Prairie Wetland Subregion; P = Aspen Parkland Continental Prairie Wetland Subregion; F = adjacent forested areas; # = 2003 samples; x = from locations in Brooks and Kelton (1967) and Canadian National Collection.

Species G P F

BELOSTOMATIDAE

Belostoma flumineum Say x #

Lethocerus americanus (Leidy) x #

L. griseus (Say) x

Corixidae

Arctocorisa sutilis (Uhler) x x

Callicorixa alaskensis Hungerford

x #

C. audeni Hungerford # # x

Cenocorixa bifida bifida (Hungerford)

# # x

C. dakotensis (Hungerford) # # x

C. expleta (Uhler) # # x

C. utahensis (Hungerford) # # x

Corisella tarsalis (Fieber) # x

Cymatia americana Hussey # # #

Dasycorixa hybrida Hungerford x x

D. rawsoni Hungerford # # x

Hesperocorixa atopodonta (Hungerford)

# x x

H. laevigata (Uhler) # # x

H. michiganensis (Hungerford) x #

H. minorella (Hungerford) x x

H. scabricula (Walley) x x

H. vulgaris (Hungerford) # x #

Palmacorixa buenoi Abbott x x

P. gillettei Abbott x

P. janeae Brooks x x

Sigara alternata (Say) # x #

S. bicoloripennis (Walley) # # x

Species G P F

S. conocephala (Hungerford) # #

S. decorata (Abbott) # x

S. decoratella (Hungerford) # # #

S. fallenoidea (Hungerford) x x x

S. grossolineata Hungerford # x x

S . lineata (Forster) # x x

S. mathesoni (Hungerford) # x

S. mullettensis (Hungerford) x #

S. penniensis (Hungerford) x #

S. solensis (Hungerford) # # #

S. trilineata (Provancher) x #

S. washingtonensis Hungerford # x

Trichocorixa borealis Sailer # # x

T. sexcincta (Champion) # #

T. verticalis interiores Sailer # # x

NEPIDAE

Ranatra fusca Palisot x x #

NOTONECTIDAE

Buenoa confusa Truxal x x x

B. macrotibialis Hungerford x # x

B. margaritacea Torre Bueno #

Notonecta borealis Hussey # x x

N. insulata Kirby x x

N. irrorata Uhler x x

N. kirbyi Hungerford # # x

N. spinosa Hungerford x

N. undulata Say # x #

PLEIDAE

Neoplea striola (Fieber) x #


2003), resulting in the loss of about 1.2 million ha of prairie wetlands to agricultural use (Whitesell 1970; Hummel 1989). This dramatic loss of wetlands since settlement in the 1850s is well-documented in the northern United States (Beazley 1993) and in parts of the Canadian prairies (Hanuta 2001).

The loss of natural wetland habitat has created a great challenge for biodiversity conservation on the prairies (Gibbs 2000). Fortunately, most of the aquatic Hemiptera occur in a variety of aquatic habitats in the prairies (Table 5), and the majority also occur in forested wetland habitats (Table 6). However, some of this good fortune is tempered because forest disturbance can negatively impact wetlands in the Boreal Plain and Boreal Shield ecozones (Prepas et al. 2003), and the boreal forest is expected to be impacted by climate change (Wheaton et al. 1987). In addition, remaining wetlands in the prairies will continue to be placed under pressure, as climate change is expected to increase drought during the summer growing season (Nuttle 1993).

Other human activities may help conservation of some wetland biota. For example, dugouts have been constructed across the Continental Prairie Wetland Region to solve livestock water supply problems. Dugouts also collect surface runoff in the “water months.” Such man-made water bodies can provide habitat for the aquatic Hemiptera and other aquatic biota of the prairies. Hence, the observation that 27 of the 35 species collected in 2003 were found either in dugouts or in dugouts with Typha margin may be important (Table 5).

Such substitutes for the natural wetland habitats may function well for much of the aquatic waterbug fauna, but they evidently do not provide habitat for all prairie grassland and parkland species. Cenocorixa expleta and Dasycorixa rawsoni were collected only in saline lakes and ponds. As a result, these prairie habitats need special conservation. Because they typically demonstrate large seasonal changes in water volume and salinity (Hammer 1978; Lieffers and Shay 1983), many saline lakes may be highly affected by an anticipated drying trend associated with climate change in the next few decades (Williams et al. 1988).

Acknowledgements

Research reported in this chapter was supported by grants to G.G.E. Scudder from the Natural Sciences and Engineering Research Council of Canada. Dr. R.G. Foottit (Agriculture and Agri-Food Canada, Ottawa) kindly allowed study of the material in the Canadian National Collection. We are indebted to Dan Buffett (Ducks Unlimited Canada) and Dr. U.T. Hammer (University of Saskatchewan) for information and help with literature. Launi Lucas kindly prepared the figures, tables, and manuscript for publication.

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