Aquatic Macroinvertebrate Biodiversity
of Pipestone Creek in Saskatchewan
Phillips, I.D., D. Parker, and G. McMaster. 2008. The aquatic invertebrate fauna of a northern prairie river: range extensions and water quality characteristics. Western North American Naturalist 68:173-85.
Project Overview and Objectives:
The southern third of Saskatchewan has limited surface water resources. The water that does exist is therefore extremely valuable (Fung et al 1999). Water demands for human consumption, agriculture, irrigation, hydroelectricity and increased recreational opportunities have resulted in the damming of most major waterways in the southern part of the province. Impounded rivers and streams are extremely impacted habitats due to the change from running water (lotic) to reservoir/lake (lentic). This eliminates many types of macroinvertebrates from the habitat because they can only live in flowing water. There are other alterations such as seasonal water flows and thermal patterns (Lehmkuhl 1972), contaminant concentrating and associated water diversions. Urban centers not only consume water but also change runoff patterns and add a wide range of contaminants to the water via storm sewers and inadequately treated sewage. Sensitive riparian habitats are damaged by shoreline resorts and cattle grazing that affect vegetation composition and add sediments and pollutants to the water. The impacts of these human activities on waterways will likely become more pronounced as predicted global warming changes occur, similar to what is proposed for boreal lakes (Schindler et al 1996).
In the spring of 2006 the Saskatchewan Watershed Authority contracted AquaTax Consulting to do a preliminary survey of the Pipestone Creek Watershed as a means to begin preparing baseline data on the aquatic macroinvertebrate communities of the watershed.
Pipestone Creek drains an area of 1340 km2 of aspen parkland in the southeastern corner of Saskatchewan. It is a low gradient stream that meanders along the bottom of a glacial spillway, the Pipestone Spillway, which drained Lake Indian Head about 12,700 years BP (Gordon 1979). The creek eventually flows into Manitoba, enters Oak Lake and ultimately the Souris River System. Numerous permanent and intermittent streams, oxbow lakes, beaver ponds and wetlands are associated with the Pipestone Creek along its course. Two manmade dams on the creek have formed Pipestone Lake and Moosomin Lake. During spring runoff and periods of high precipitation, flow rates can be swift in undammed portions of the channel, but during late summer or drought conditions the channel may become dry.
Pipestone Creek is an important source of water for many communities and farms in southeastern Saskatchewan. A number of game fish, waterfowl species and deer inhabit the watershed, providing recreation and food to the area residents. The creek and its wetlands are also breeding habitat for biting flies, which not only are a nuisance but can transmit diseases.
Human activity has impacted Pipestone Creek throughout its length. The Moosomin Dam, constructed in 1955, created the Moosomin Lake reservoir that not only supplies water to the community of Moosomin, but is also a popular recreational area for the residents. Since its construction, communities and farmers downstream in Saskatchewan and Manitoba have raised concerns regarding the amount of water retained in the reservoir during dry periods. The dam also acts as barriers for fish and obstacles for non-flying macroinvertebrates.
Bridges and culverts, part of innumerable gravel roads, trails and highways that cross the creek, further modify flow rates and create artificial backwaters. Many communities within the watershed have sewage lagoons and golf courses that potentially increase contamination to the creek and alter runoff. The creek receives runoff from cropland that may contain chemical pesticides and fertilizers. Farmers use the creek for watering livestock and associated riparian vegetation provides forage for animals throughout the year. Cattle grazing and watering in the riparian zone enrich the water and break down the shoreline and remove important plants and shrubs that protect the shoreline from erosion. Further impacts may occur as the area is explored for petroleum reserves. There is also the added threat of increased growth of communities in the watershed and development of more intensive cattle feedlots and hog barns.
Sampling efforts were concentrated at three sites on the Pipestone Creek, an unnamed tributary and a site on the Little Pipestone Creek as it enters the Moosomin Reservoir.
Pipestone Creek Site 1 (50-15-12N/102-37-42W): At this site a trail and bridge artificially creates an open water wetland with an approximately 60/40 split of open water and emergent vegetation, mainly Typha spp. The substrate in the open water is submersed vegetation over gravel and silt. The substrate in the emergent vegetation area is a decaying vegetation mat over a predominantly silt substrate. Initially, April 25, there was moderate water flow over parts of the gravel trail (water depth 20-30 cm) and under the bridge (water depth 70 cm). However, beaver dammed these areas and maintained the dam throughout the summer and fall. This essentially stopped water flow and stabilized the water level behind the dam. Downstream the creek is further obstructed by a gravel road, which forces the creek through culverts. Sampling was conducted upstream from the trail. Cattle grazing and drinking heavily impact the riparian zone (shoreline) and the beaver dam. Willows are the dominant shrubs and small clumps of aspen are present.
Pipestone Creek Site 2 (50-07-47N/101-58-39W): At Site 2 Pipestone Creek flows through a steep sided artificial channel constructed to improve water flow through a bridged gravel road crossing downstream from the collection site. Water current is moderately rapid in spring and early summer. However, by late summer water levels declined to such an extent that water flow was reduced to small trickles between pools. The substrate is silt in depositional areas and moderate cobble and gravel in erosional areas. The water is very turbid and all submersed substrates including macrophytes are covered by silt. Mid channel water depths in spring were 1.6 m or greater in the pools. There is much evidence of shoreline erosion and slumping. Cattle graze to the waters edge. Riparian shrubs include dogwood.
Unnamed Tributary, Pipestone Creek Site 3 (50-04-33N/101-56-11W): This unnamed intermittent creek flows into Pipestone Creek during spring and high precipitation periods. The collecting site was at the culvert of a gravel road crossing. By late summer the stream was reduced to pools, which become dry during the remainder of the year. The substrate is fine organic silt with decaying vegetation. Emergent vegetation in the ditch included Typha, sedges, and grasses. Submerged vegetation was mostly Utricularia. Cattle grazing and watering occurs in the field adjacent to the ditch.
Little Pipestone Creek Site 4 (50-02-02N/101-41-41W): The Little Pipestone Creek flows into wetlands associated with Moosomin Lake less than 2 km from the Moosomin Dam. The reservoir affects flow rates and increase water levels at the sampling site. Just downstream from the collection site is a bridged gravel road crossing. The creek channel is steep sided and up to 1.8 m deep and 5 m +/- across. The water is clear except when cattle disturb the substrate. The bottom substrate is silt intermixed with decaying vegetation debris. Vegetation is abundant with Typha being the most common emergent. Submerged vegetation includes, Utricularia, Rannuculus, and Myriophyllum. Shore vegetation includes sedges and a variety of shrubs and grasses. The area is fenced for cattle, which use the creek for water and grazing with associated damage to the riparian zone.
Pipestone Creek Site 5 (49-53-11N/101-26-57W): This site is at a bridged gravel road crossing approximately 40 km downstream from the Moosomin Dam. During spring the creek is fast flowing. However, flow rates are dependent on the amount of water released at the dam. Summer and fall water flow declined dramatically until August when only trickles and pools were present at the site. Significant cut banks are present on both shores. At the sampling site the substrate is large cobble with smaller and larger rocks, and sand and silt in sheltered areas. A gravel trail crosses the creek just downstream of the bridge. A small island is just downstream from the trail. At the site the creek is very turbid. Fine silt coats all submersed plants, rocks and logs. Macrophyte growth is minimal. Upstream and downstream of the site cattle graze the shorelines and use the creek for water.
Sampling and Sample Processing Methods
Sampling was conducted during four periods in 2006; April 25, May 29 and 30, July 5 and 6 and August 14, 15, and 16. Site 3 was only completely sampled on May 29 and July 5.
To document the macroinvertebrate biodiversity at each site a 1 mm meshed, D-framed aquatic net and a 0.75 mm sieve were used to qualitatively sample as many microhabitat types that could be accessed in chest waders. Submerged rocks, logs, etc were examined for adhering macroinvertebrates. Samples were partially processed at the site. Aerial sweep samples of the riparian vegetation were taken to collect adult insects. These samples were preserved in 70% alcohol. At the lab representative specimens of each distinct macroinvertebrate type were sorted from the dip net samples and aerial sweep samples, using the naked eye and a dissecting microscope at 6X. These specimens were preserved in 70% alcohol, pinned, or mounted on microscope slides and identified to the lowest practical taxonomic level.
In addition, a composite proportional dip net sample was taken either as a kick sample, if current velocity and water depth allowed, or as a series of jabs and sweeps of the substrate and submerged vegetation. These samples were preserved in the field with 100% alcohol and returned to the lab for processing.
Composite proportional dip net samples were washed to remove any remaining silt using a 500-m sieve and then divided into 1/8 or 1/16 sample fractions using a piece of Plexiglas (Cuffney et al. 1993). Subsamples were randomly chosen and processed under a dissecting microscope at 6X until a count of 300 macroinvertebrates was attained or the entire sample had been processed. We identified macroinvertebrates to the lowest level possible and enumerated them. We assigned feeding group categories to each taxa based on the literature (Pennak 1989, Clifford 1991, Merritt and Cummins 1996, Mandaville 2002). Data were then used to determine percent composition of each taxa (taxa individuals / total individuals * 100) and feeding group at the sites. Similarity cluster analysis was performed on taxonomic and feeding group data using a Multi-Variate Statistical Package (MVSP; Ko - vach 1999). The Weighted Pair Group Average Method (WPGMA) was used to account for fewer sampling dates at site 3 (Kovach 1999). Rarefaction was used to estimate the species richness accumulation curve (Colwell 2006).
Results and Discussion
Over 250 different types of aquatic "bugs" were collected in the study.
|Summary of Aquatic "Bugs" collected
in Pipestone Creek and tributaries
|Moss Animals (Bryozoa)||1
|Snails, Limpets, Clams (Mollusca)||20|
|Scuds, Crayfish (Macrocrustacea)||3|
|Water Mites (Acari)||?|
|Dragonflies and Damselflies (Odonata)||26|
|True Bugs (Hemiptera)||23|
|Two-winged Flies (Diptera)||85|
Successive sampling dates increased the number of taxa recorded for each site and the entire study. However, there is no clear asymptote to indicate true taxonomic richness has been fully estimated. Therefore there are likely still a number of taxa yet to be found in the creek.
Since very little aquatic bug research has been done on the waterways in southeastern Saskatchewan this study recorded significant Saskatchewan range extensions for 12 mayflies: Acerpenna pygmaea, Baetis brunneicolor, Baetis flavistriga, Baetis tricaudatus/brunneicolor, Callibaetis ferrugineus, Procloeon sp, Caenis amica, Caenis latipennis, Leucrocuta hebe, Stenacron interpunctatum, Stenonema terminatum, and Leptophlebia sp. Most of these species were previously known from the boreal forests of the province (Webb 2002). The water scorpion, Rantra fusca, has not been officially reported from Saskatchewan (Brooks and Kelton 1967) but is known to occur in the east central area of the province (Parker 2004). The presence of the stonefly Perlesta placida (= dakota) is also a range extension to the southeast corner of the province for this species (Dosdall 1992, Dosdall and Lehmkuhl 1979). Caddisflies (Trichoptera), in Saskatchewan have not been well studied outside the boreal forests (Smith 1984). Twelve caddisflies identified in this study had their ranges in Saskatchewan extended to the southeast corner of the province: Hydropsyche bifida, Hydropsyche alternans, Ithytrichia clavata, Nectopsyche diarina, Oecetis immobilis, Limnephilus cf janus, Triaenodes injustus, Limnephilus hyalinus, Limnephilus infernalis?, Limnephilus labus?, Limnephilus rhombicus?, and Philarctus quaeris (Floyd 1995, Glover 1996, Nimmo 1987, Smith 1984, Wiggins, 1998). The chironomid, Z. maromata, was only recently reported from Saskatchewan near Regina (Parker and Glozier 2005). Its collection in the Pipestone Creek watershed may indicate the immigration path it used to reach Saskatchewan from eastern Canada. Since the Pipestone Creek has links to eastern waterways of Manitoba and Ontario and ultimately New England many more significant zoogeographical records are likely to be discovered in this area. This eastern connection also makes the Pipestone Creek a potential route for invasive species to enter the province. If such species become established they could detrimentally impact the waterways of the province.
Mosquitoes, biting midges, blackflies and horseflies were collected in the study. If environmental conditions are right the Pipestone Creek Watershed may harbour large numbers of biting flies which not only could be a biting nuisance to humans and their animals but could also transmit diseases.
Aquatic bugs are important to the operation of aquatic ecosystems. Each has a "job" to do which makes the system work much as a town or a city has people doing various tasks such as teachers, doctors, police, fire, garbage collectors, business people, etc. One way of studying bug communities is to see how each "job" is represented in samples. Most bug types can be assigned a particular "job" based on what food it eats. In a bug community there are generally, collectors/gathers (These collect food from the bottom gunk or filtering it out of the water.), predators (These eat other bugs by catching and chewing them up.), shredders (These chew up dead plants and digest the microorganisms that are attached to them.) and piercers (These have mouthparts that poke holes into plants and other bugs and suck the juices out.) By looking at the number of bugs doing each job information of how the ecosystem works, and in some cases if it is polluted, can be determined.
|% Composition of "Bug" Feeding Groups Collected at Sites|
|Site 1||Site 2||Site 3||Site 4||Site 5|
As can be seen from the above table Sites 1, 2, and 3 have more collectors/gatherers than the other sites and Sites 4 and 5 have more scrapers/grazers. The similarity of the site feeding group communities can also be compared and the results graphed. This graph shows that Site 5 and 4 are most similar to each other while Site 1, 3 and 2 form another group of similar sites.
Funding for the research was provided by a grant from the Fish and Wildlife Development Fund through the Saskatchewan Watershed Authority (G. McMaster and E. Soulodre). Thanks to G. Ekert, T. Houderstad, W. Kemp, G. Rutledge and J. van Eaton for allowing access to the collection sites. J. Halpin and V. Keeler provided field assistance. J. Halpin assisted in processing the samples.