Aquatic "Bugs" of Candle Lake, Saskatchewan

Aquatic macroinvertebrates, or "bugs", are important to the over all health of aquatic ecosystems like lakes and rivers. They perform a vital role by feeding on dead and decaying material and recycling it back into the food web. They are also important food sources for many fish, waterfowl and songbirds. At present, little or no species level research has been conducted on these communities inhabiting Saskatchewan boreal lakes.

The biological importance of the "bug" community makes it a useful tool for assessing and monitoring lakes and rivers impacted by pollutants, mines and forestry practices. Severe cases of contamination or habitat disturbance can significantly alter the "bug" community to the extent it affects the food available for fish and birds at critical periods of their life cycles. This can result in reductions in overall numbers, growth rates, and breeding success for these valued species. Many of the bugs react rapidly to these impacts and can provide valuable early warning signs of something wrong with the ecosystem so that changes can be made to eliminate or reduce the problem before unalterable damage occurs to fish and bird populations and the habitat as an whole.

Candle Lake

Candle Lake is located on the southern edge of the boreal forest near the center of the province. Saskatchewan Environment (SEM) conducted a study of the lake with special reference to the fish populations. To compliment this study, SEM retained the services of AquaTax Consulting to survey the aquatic macroinvertebrates found in the lake during the ice-free seasons of 2001 and 2002.

The results of the Candle Lake research will provide baseline data to assess impacts of future expansions of recreational developments on the lake. It will also supplement existing biodiversity information for Saskatchewan and provide a better understanding of how boreal lake ecosystems function in general. These results in turn will be useful to assess impacts of developments such as mining within the area of Candle Lake and on other boreal lakes in the province and Canada.


The objectives of the research are three-fold:

1: Document the species level biodiversity of macroinvertebrates associated with Candle Lake.

2: Determine emergence periods (i.e. hatch times), life cycles, habitat preferences, and densities of the common aquatic insects found in the lake.

3: Document the benthic community of macroinvertebrates across the lake.

Study Sites

Three primary shoreline sites along the southeast shore of Candle Lake are being used for this research.

Onechassa Site A:

Candle Lake Site 1

Is located near Onechassa Subdivision. It has a rocky, wave washed shoreline. The lake bottom at this site is very rocky with little or no vegetation or sandy silt. The exposed nature of shoreline provides microhabitats for a number of species of aquatic insects, including some that are more typical of river habitats.

Sandy Bay Site B:

Candle Lake Site 2

This site is located near Sandy Bay Campground. It is a more sheltered area. The shoreline, although rocky, is protected to some extent by being in a slight bay and a bulrush bed. The bottom is sandy silt with some areas of submerged vegetation and logs that provide microhabitats for a number of "bugs".

North Subdivision Site C

Candle Lake Site 3

This site is near the North Subdivision. It has a floating "wetland" area in addition to similar habitats at the other two sites. The "wetland" area is a mat of plant roots and stems that floats in some areas about 40 cm above the real substrate. In 2001, this area was flooded for most of the year and provided habitat to a number of different "bug" species not found at the other two sites or the open water area immediately surrounding the bog. The wetland also provided shelter to large numbers of young fish fry and minnows.

Study Methods

At each of the sites dip net samples were taken of the aquatic "bugs" about every two or three weeks throughout the ice free season. The "bugs" collected were taken back to the lab where they were identified and some raised from larvae to adults.

At the North Subdivision site, 15 floating emergence traps were placed in the "bog" and surrounding open water area. These traps collected adult aquatic insects as they emerged from the water (hatches) in the lake. Samples were collected from the traps three times a week. At the lab the specimens were identified and counted to determine what species were emerging, when and in what densities.

An Ekman dredge was used to sample the lake bottom at different water depths (0-5m, 5-10m, 10-15m) across the lake to determine the species and densities of "bugs" inhabiting deeper areas.

Brief Summary of Results

Approximately 244 different species of aquatic "bugs" were collected from Candle Lake as listed below. The insects make up the majority of the species of "bugs" in Candle Lake.

At the rocky Onechassa Subdivision site a water boatman (Hemiptera: Corixidae) species, Sigara trilineata, was found swimming in the water in very large numbers throughout most of the year. Snail-like sand cases made by larvae of the caddisfly (Trichoptera) Helicopsyche borealis were found on the rocks at this site as was a very flat mayfly (Ephemeroptera) Stenonema femoratum that is more typical of rivers and streams but due to the wave action and high oxygen levels this species can survive in Candle Lake. In mid June, the mayfly species Leptophlebia nebulosa (dark coloured about 1 cm long) emerged ("hatched") in massive numbers at all three sites. One of the most impressive "bugs" (7 cm long) in Saskatchewan, the giant water bug (Hemiptera: Belostomatidae: Lethocerus americanus), was also collected.

Similar numbers of taxa were collected from the three qualitative sites: Site 1 - 112, Site 2 - 106, Site 3 - 128. However, the physical habitat differences of the sites resulted in dissimilar community compositions with only 60% (Sorensons' Coeff.) or less in site comparisons.

The emergence traps collected 34,714 adults from June 3 to Sept 30, 2002. Emergence density averaged 4723 adults/sq m across the site. The open water traps collected 54% of the total with the bog traps collecting significantly fewer insects than the other habitat types. The mayflies emerged mostly from the emergent vegetation on the strength of a mass emergence of Leptophlebia nebulosa from June 14 to June 26. Peak emergence reached 126/sq m/day on June 21. The dragonflies and damselflies made up only 0.1% of the adults collected in the traps. Caddisflies prefered to emerge from the open water than the other habitats. Helicopsyche borealis was the most commonly collected species making up 52% of the fauna. It emerged during July and almost entirely from the open water. Chironomids (non-biting midges) made up over 91% of the insects collected and most (57%) emerged from the open water. Unfortunately, species determinations were not conducted due to budgetary restraints.

Ekman sampling revealed that the 0-5m and 5-10m depths had the richest fauna, between 14 and 19 taxa. Only 7 or 8 taxa were collected from the deepest depth, 10-15m. This deepest zone was dominated by chironomids (non-biting midges) and no amphipods were collected in this zone.

Ekman sampling is the typical method used for sampling lakes in biomonitoring protocols. Comparisons of qualitative littoral sampling, emergence traps results and ekman sampling in this study revealed that qualitative sampling collected by far the most species, 210. Emergence traps collected 51 species and Ekman samplers only 38 species. It is apparent that a variety of sampling methods should be used instead of reliance on the ekman sampling method alone to ensure the diversity of aquatic "bugs" be documented.

Publication: Parker, D, R. Hlasny and J. Webb, 2008. Biodiversity and adult emergence periods of mayflies (Ephemeroptera) inhabiting Candle Lake, Saskatchewan. Blue Jay. 66:96-104.

Candle Lake Species List:

Nematomorpha (Horsehair worms)

  • Unidentified spp

Leeches (Hirudinea)

  • Erpobdellidae
    • Dina dubia (Moore & Myer)
    • Erpobdella punctata Leidy
    • Moorebdella fervida Verrill ?
    • Nephelopsis obscura Verrill
  • Glossiphoniidae
    • Glossiphonia complanata (Linnaeus)
    • Helobdella stagnalis (Linnaeus)
    • Theromzyon sp (Castle)
  • Piscicolidae
    • Piscicola milneri Verrill

Snails & Limpets (Gastropoda)

  • Ancylidae (Limpets)
    • Ferrissia rivularis (Say)
  • Lymnaeidae (Pond Snails)
    • Bakerilymnea bulimoides Lea
    • Fossaria sp
    • Lymnaea stagnalis jugularis (Say)
    • Stagnicola catascopium (Say)
    • Stagnicola elodes (Say)
    • Stagnicola reflexa (Say)
  • Physidae (Tadpole Snails)
    • Physa gyrina gyrina Say
    • Physa jennessi skinneri Taylor Say
  • Valvatidae (Valve Snails)
    • Valvata sincera sincera (Say)
    • Valvata tricarinata (Say)
  • Planorbidae (Rams Horn Snails)
    • Gyraulus circumstriatus (Tryon)
    • Gyraulus deflectus (Say)
    • Helisoma anceps anceps (Menke)
    • Helisoma pilsbryi infracarinatum Baker
    • Helisoma trivolvis (Carpenter)
    • Planorbula armigera (Say)
    • Promenetus exacuous exacuous (Say)

Clams (Pelecypoda)

  • Sphaeriidae (Pea Clams)
    • Pisidium spp.
    • Sphaerium spp.
  • Unionidae
    • Anodonta grandis Say

Scuds & Crayfish (Crustacea)

  • Scuds (Amphipoda)
    • Hyalella azteca (Saussure)
    • Gammarus lucustris Sars
  • Crayfish (Decapoda)
    • Orconectes virililis (Hagen)


  • Mayflies (Ephemeroptera)
    • Baetidae
      • Baetis sp
      • Callibaetis ferrugineus (Walsh)
      • Procloeon pennulatum Eaton
      • Procloeon quaesitum (McDunnough)
    • Caenidae
      • Caenis latipennis Banks
    • Ephemeridae
      • Ephemera simulans Walker
      • Hexagenia limbata limbata Serville
    • Heptageniidae
      • Stenacron interpuctatum (Walker)
      • Stenonema femoratum (Say)
    • Leptohyphidae
      • Tricorythodes minutus Traver
    • Leptophlebiidae
      • Leptophlebia cupida (Say)
      • Leptophlebia nebulosa (Walker)
  • Dragonflies & Dameselflies (Odonata)
    • Coenagrionidae
      • Coenagrion clausum Morse
      • Coenagrion resolutum (Hagen)
      • Enallagma cyathigerum (Charpentier)
      • Enallagma hageni (Walsh)
      • Nehalennia irene (Hagen)
    • Lestidae
      • Lestes disjunctus Selys
      • Lestes congener Hagen
    • Aeshnidae
      • Aeshna eremita Scudder
      • Aeshna interrupta (Walker)
      • Aeshna sitchensis Hagen
      • Aeshna umbrosa Walker
    • Corduliidae
      • Cordulia shurtleffi Scudder
      • Tetragoneuria spinigera Selys
    • Libellulidae
      • Leucorrhinia borealis Hagen
      • Leucorrhinia glacilis Hagen
      • Leucorrhinia hudsonica (Selys)
      • Leucorrhinia intacta (Hagen)
      • Libelullula quadrimaculata Linnaeus
      • Sympetrum danae Sulzer
      • Sympetrum internum Montgomery
      • Sympetrum cf obtrusum (Hagen)
  • True Bugs (Hemiptera)
    • Belostomatidae (Giant water bugs)
      • Lethocerus americanus (Leidy)
    • Corixidae (Water boatman)
      • Callicorixa audeni Hungerford
      • Cenocorixa bifida (Hungerford)
      • Cenocorixa dakotensis (Hungerford)
      • Cenocorixa expleta (Uhler)
      • Hesperocorixa michiganesis (Hungerford)
      • Sigara bicolorpennis (Walley)
      • Sigara conocephala (Hungerford)
      • Sigara decoratella (Hungerford)
      • Sigara fallenoidea (Hungerford)
      • Sigara lineata (Forster)
      • Sigara mullettensis (Hungerford)
      • Sigara solensis (Hungerford)
      • Sigara trilineata (Provancher)
    • Gerridae (Water striders)
      • Gerris buenoi Kirkaldy
      • Gerris dissortis Drake & Harris
      • Gerris pingreenis Drake and Hottes
    • Microveliidae
      • Microvelia buenoi Drake
    • Notonectidae (Backswimmers)
      • Notonecta kirbyi Hungerford
      • Notonecta undulata Say

Insecta continued

  • Caddisflies (Trichoptera)
    • Helicopsychidae
      • Helicopsyche borealis (Hagen)
    • Hydropsychidae
      • Hydropsyche alternans Walker
    • Hydroptilidae
      • Hydroptila sp
      • Ithytrhichia clavata Morton
      • Orthotrichia cristata Morton
    • Lepidostomatidae
      • Lepidostoma sp
      • Lepidostoma togatum (Hagen)
    • Leptoceridae
      • Ceraclea cf annulicornis Stephen
      • Mystacides interjecta Banks
      • Mystacides sepulchralis (Walker)
      • Nectopsyche diarina (Ross)
      • Nectopsyche exquisita (Walker)
      • Oecetis disjunctus (Banks)
      • Oecetis inconspicua complex (Walker)
      • Triaenodes sp
      • Ylodes reuteri (MacLachlan)
    • Limnephilidae
      • Limnephilidae sp
      • Anabolia bimaculata (Walker)
      • Asynarchus curtus (Banks)
      • Asynarchus cf montanus (Banks)
      • Hesperophylax cf desingatus (Walker)
      • Glyphopsyche irrorata (Fabricius)
      • Limnephilus cf externus Hagen
      • Limnephilus extractus Walker
      • Limnephilus infernalis (Banks)
      • Limnephilus nigriceps (Zetterstedt)
      • Limnephilus partitus Walker
      • Limnephilus sackeni Banks
      • Limnephilus sansoni Banks
      • Nemotaulius hostilis (Hagen)
    • Molannidae
      • Molanna flavicornis Banks
      • Molannodes tinctus Zetterstedt
    • Phryganeidae
      • Agrypnia improba (Hagen)
      • Agrypnia pagetana Curtis
      • Agrypnia straminea Hagen
      • Phryganea cinerea Walker
      • Ptilostomis semifasciata (Say)
    • Polycentropodidae
      • Nyctiophylax affinis (Banks)
      • Polycentropus cinereus Hagen
      • Polycentropus flavus (Banks)
  • Beetles (Coleoptera)
    • Dysticidae (Diving Beetles)
      • Colymbetes sp
      • Dytiscus circumcinctus Ahrens
      • Hydroporus sp
      • Hygrotus sp
      • Ilybius sp
      • Liodessus cf obscurellus (LeConte)
      • Nebrioporus depressus (Fabricius)
      • Nebrioporus macronychus (Shirt and Angus)
      • Oreodytes scitulus (LeConte)
      • Potamonectes sp
      • Rhantus binotatus Harris
      • Rhantus sericans Sharp
      • Rhantus wallisi Hatch
    • Gyrinidae (Whirligig Beetles)
      • Gyrinus cf maculiventris LeConte
      • Gyrinus pectoralis LeConte
    • Haliplidae (Crawling Beetles)
      • Haliplus spp
      • Haliplus canadensis Wallis
      • Haliplus cribarius LeConte
    • Hydrophilidae (Water scavenging beetles)
      • Hydrobious fuscipes (Linnaeus)
      • Hydrochara sp
  • Two-winged Flies (Diptera)
    • Ceratopogonidae (No-see-ums)
      • Ceratopogonidae sp
    • Chironomidae (Non-biting midges)
      • Ablabesymia sp
      • Monopelopia boliekae Beck and Beck
      • Procladius sp
      • Procladius denticulatus Sublette
      • Thienemannimyia complex (Edwards)
      • Thienemannimyia fusciceps (Edwards)
      • Cricotopus spp
      • Epiocladius sp
      • Heterotrissocladius marcidus (Walker)
      • Parakiefferiella subaterrima (Malloch)
      • Psectrocladius sp
      • Chironomus sp
      • Chironomus decorus Johannsen
      • Chironomus plumosus (Linnaeus)
      • Cladopelma collator (Townes)
      • Cryptochironomus fulvus complex
      • Cryptochironomus conus Mason
      • Cryptochironomus curryi Mason
      • Cryptochironomus psittacinus (Meigen)
      • Cryptochironomus ramus Mason
      • Cryptotendipes sp
      • Dicrotendipes sp
      • Dicrotendipes cf nervosus Staeger
      • Einfeldia/Chironomus sp
      • Endochironomus sp
      • Endochironomus nigricans Johannsen
      • Glyptotendipes barbipes (Staeger)
      • Glyptotendipes lobiferus (Say)
      • Glyptotendipes paripes (Edwards)
      • Microtendipes sp
      • Omisus cf pica Townes
      • Pagastiella sp
      • Parachironomus sp
      • Paratendipes
      • Phaenopsectra sp
      • Polypedilum sp
      • Polypedilum nubeculosum (Meigen)
      • Stictochironomus sp
      • Tribelos sp
      • Pseudochironomus sp
      • Pseudochironomus cf badius Saether
      • Pseudochironomus cf pseudoviridis (Malloch)
      • Cladotanytarsus sp
      • Micropsectra sp
      • Micropsectra nigripila (Johannsen)
      • Paratanytarsus sp
      • Stempellinella sp
      • Tanytarsus sp
      • Tanytarsus guerlus (Roback)
    • Culicidae (Mosquitoes)
      • Aedes vexans (Meigen)
    • Dixidae
      • Dixella sp
    • Tabanidae (Horseflies & Deerflies)
      • Chrysops sp
      • Chrysops ater Macquart
      • Chrysops mitis Osten Sacken
      • Hybomitra astutus (Osten Sacken)
      • Chrysops aestuans Van der Wulp
    • Sciomyzidae (Snail killing flies)
      • Sciomyzidae sp
    • Tipulidae (Crane flies)
      • Tipulidae spp.
      • Nephrotoma sp.
      • Tipula sp.


Funding for this research was provided by Saskatchewan Environment and Resource Management. J. Halpin assisted with field collections and sample processing. V. Keeler and J. Webb assisted with field collecting. J. Gabora, M. Hlasny, R. Hlasny, T. Hlasny, A. Nelson, C. Nelson, G. Nelson, T. Person and K. Willer assisted with emergence trap sampling and Ekman sampling.