Past Ciborowski Lab Members

Below you can find a list of past Ciborowski graduate students, along with their thesis titles and abstracts. PDF versions of full theses are linked where available.

Kathryn Williams (M.Sc. 2014)
Thesis Title: Relative distribution and biomass of invertebrates in fens and marshes in the boreal region of northeastern Alberta

Thesis Abstract: Habitat selection determines the environment characteristics experienced by the individual. Arthropod assemblages are better predicted by plant community characteristics than by other environmental features. However, the role of local habitat characteristics (microhabitat structure, food) in regulating invertebrate distribution is less well known. The invertebrate fauna of northeastern Alberta’s boreal peatlands and wetlands is especially poorly documented. I investigated invertebrate-vegetation associations of between and within fens and marshes, and variation across wetland hydrological zones. Family richness and biomass were greatest in wet meadow zones of marshes. Sampling instruments used to evaluate microhabitats collected complementary invertebrate types and different abundances. Vacuum sampling captured many phytophilous and soil associated fauna. Sticky traps caught mainly small-bodied, flying insects. Aerial sweep netting caught some large organisms but inadequately represented wetland biota. Overall, invertebrate composition was better predicted by vegetation zone than by hydrological regime or plant species richness within wetlands.

Sheeva Nakhaie (M.Sc. 2013)
Thesis Title: Avian species-area relationships and environmental covariates in natural and constructed wetlands of northeastern Alberta.

Thesis Abstract: I examined the patterns of species distribution and richness as they relate to area in boreal wetlands of northeastern Alberta. I conducted point counts of bird species in natural and constructed wetlands of various sizes. Plant species richness, habitat attributes, and habitat heterogeneity were also estimated to determine whether these factors influenced the strength of the avian species-area relationship. The species-area relationship was statistically significant in natural but not in constructed wetlands. Plant richness varied independently of area for both wetland classes. Area and anthropogenic disturbance were significant predictors of avian species richness in natural wetlands, but richness was uncorrelated with all variables in constructed wetlands except for habitat heterogeneity. Although mean avian species richness was similar between natural and constructed wetlands overall, community composition differed markedly and was most likely related to natural wetlands’ greater age, larger size and distance from busy roads relative to constructed wetlands.

Ellen Green (M.Sc. 2012)  (Coadvisor: Dr. Lynda Corkum)
Thesis Title: The effect of mayfly (Hexagenia (Ephemeroptera: Ephemeridae)) nymphal burrowing activity on egg hatching and subsequent development of early instar individuals: implications for intercohort interactions

Thesis Abstract: Bioturbation can cause the burial of eggs in sediments, isolating them from oxygen and consequently preventing development. I investigated the effects of burrowing on egg hatching and nymph development in burrowing mayflies (Hexagenia spp.). First, I examined the effects of burial on egg hatching. More eggs hatched on the sediment’s surface than at any other depth. Furthermore, egg burial contributed to greater size variation among hatchlings, possibly from delays in hatching of buried eggs. Subsequently, I investigated the effect of burrowing on the vertical distribution and hatching of eggs within sediments. Reduced hatching and greatest hatchling size variation occurred in trials containing higher densities of nymphs, suggesting that benthic activity facilitates burial of eggs and reduces synchrony of hatching. Under natural conditions, such activities may contribute to the formation of multiple cohorts that characterize Hexagenia populations. These studies show how indirect consequences of ecological engineering can influence life history patterns.

Michael Chen (M.Sc. 2012)  (Coadvisor: Dr. Christopher Weisener)
Thesis Title: Assessing the biogeochemical development of oxygen and sulfur in oil sands fluid fine tailings in batch microcosms.

Thesis Abstract: Elevated concentrations of hydrogen sulfide produced by sulfate-reducing prokaryotes are highly reducing, and can impair function of higher trophic levels inside end-pit lakes in the Alberta oil sands region. Microcosms have previously simulated the microbial community structure of tailing ponds; they are used here as analogues of the sediment-water interface of end-pit lake environments to determine sulfide generation patterns and the behaviour of oxygen. In this study, sulfide generation was positively correlated with depth and biotic activity, with production fluxes of ~2 x 10³ nmol cm^-3s^-1. Oxygen consumption in the tailings is dependent on both biotic and abiotic processes. These results have implications for quantitatively estimating impacts of sulfide production and oxygen availability to biota, in addition to the biogeochemical cycles linked to their functional roles in tailings-affected ecosystems.

Kaitlin Kennedy (M.Sc. 2012)
Thesis Title: Growth, survival, and community composition of Chironomidae (Diptera) larvae in selected Athabasca oil sands process-affected wetland waters of northeastern Alberta

Thesis Abstract: Oil sands process water (OSPW) is toxic to many aquatic organisms. The goal of this study is to determine if or how midge (Diptera: Chironomidae) productivity and community assemblages may differ between OSPW and reference wetlands and the effects of OSPW wetland water, naphthenic acids (NA), and salts on chironomid growth and survival. Although chironomids differed in size, abundance, and community composition among wetlands, the differences were not attributable to the presence or absence of OSPW. Community composition varied with respect to wetland-specific water chemistry attributes (e.g., dissolved oxygen). Ten-d Chironomus riparius laboratory bioassays indicated that larvae grew to a smaller size when exposed to OSPW wetland water compared to reference wetland water. When C. riparius was reared for 10 d in water mimicking combinations of salts and NA, survival was significantly negatively correlated with salt and NA concentrations, and there was an antagonistic interaction between the two toxicants.

Emily Crisovan (M.Sc. 2011) (Coadvisor: Dr. Yingming Zhao)
Thesis Title: Length-at-age and size-selective mortality of the western basin Lake Erie Walleye (Sander vitreus) population, 2000-2008.

Thesis Abstract: Size-selective mortality is common in systems where selective harvesting targets a specific size- or age-class. In general, commercial and recreational fisheries selectively remove the largest and fastest growing individuals, which may have evolutionary consequences. My goals were to examine length-at-age patterns, age at first and full recruitment to the fishery, and to determine if size-selective mortality existed in a commercially and recreationally fished population of walleye in Lake Erie of the Laurentian Great Lakes between 2000 and 2008. Mean fork length-at-age was found to increase from west to east within Lake Erie for age 2 and 3 walleye. However, mean fork-length at age 1 was not statistically different among sampling areas. Walleye first recruited to the fishery at age 1 and were not fully recruited by age 3. Smaller (slower growing) individuals were found to disproportionately survive to older ages than faster-growing fish, indicating that size-selective mortality of larger (faster growing) fish occurred. Size-selective mortality will likely have a negative effect on morphological (i.e., body size) and life history traits.

Mary Sebastian (Ph.D. 2010)
Thesis Title:  Determinants and developmental consequences of organic contaminant uptake in nestling insectivorous birds.

Thesis Abstract: This research assesses the ecotoxicology of three avian species in their natural environment. Field studies investigated potential toxicological effects of organochlorine pollutants including polychlorinated biphenyls (PCBs) and dichlorodiphenyl trichloroethane (DDT) and their metabolites on wildlife with passerine nestlings as model organisms. For organisms at higher trophic levels, especially terrestrial ones the major route of exposure to persistent pollutants is food. Consequently, I estimated the diet of nestlings of populations of three species - tree swallows (Tachycineta bicolour), purple martins (Progne subis) and house wrens (Troglodytes aedon) at Point Pelee National Park, Ontario, Canada and their contaminant contents. Another route of exposure in oviparous organisms is through their eggs, so the contaminant contents in the eggs of each population were analyzed. I measured nestlings’ growth rates in the field and estimated consumption rates from those values. The contamination loads were estimated by multiplying consumption rates by food-specific contaminant concentrations and combined with egg-acquired burdens in a bioenergetics-based model to predict the bioaccumulation levels of various PCB congeners and DDE in each species. These estimates were compared with tissue contaminant concentrations of nestlings sacrificed at their fledging age. The deviations between the predicted and observed values reflected the biotransformation and absorption abilities of the nestlings.

The results of this thesis demonstrate that the accumulation of pollutants and its effects on nestling passerines in natural habitats are based on composition of food, contributions from maternal burden accumulated from breeding and overwintering locations and bioenergetics of nestlings including biotransformation capacities.

Carsten Slama (M.Sc. 2010)
Thesis Title: Sediment oxygen demand and sediment nutrient content of reclaimed wetlands in the oil sands region of Northeastern Alberta.

Thesis Abstract: Sediment oxygen demand (SOD), nutrient concentrations, and submergent macrophyte biomass were measured in reference wetlands and oil sands process material affected (OSPM) wetlands in the oil sands region of Alberta. Any or all of these factors could influence the success of wetland reclamation in this area. Gas flux and SOD chambers were deployed to determine the biological and chemical components. Nutrient concentrations were estimated from water and sediment extractions as well as PRS™ probes.

Sediment oxygen demand was slightly higher in OSPM-affected wetlands than in reference wetlands. Over 85% of SOD was due to chemical processes, likely due to ammonium oxidation. High SOD could limit benthic respiration and ultimately affect carbon stores. Reference wetlands had greater submergent macrophyte biomass than OSPM-affected wetlands but phosphorus concentration could not explain this difference. This implies that sediment oxygen demand, phosphorus concentration, and submergent macrophyte biomass are independent of one another among wetland classes.

Jesse Gardner Costa (M.Sc. 2010) - Full Thesis Text
Thesis Title: Spatial and temporal variation in sediment-associated microbial respiration in oil sands mine-affected wetlands of north-eastern Alberta, Canada.

Thesis Abstract: We measured whether carbon loss in the form of sediment-associated microbial respiration differed between unvegetated sediments of recently constructed oil sands process-affected (OSPM) and reference wetlands. Constituents of OSPM-wetlands (increased salinity, conductivity) were expected to influence respiration, increasing gas (methane and carbon dioxide) flux and sediment oxygen demands (SOD) compared to reference wetlands. However, OSPM-wetlands released 1/10th the methane of reference wetland sediments but did not differ in CO2 ebulition. Sediment oxygen demand (SOD) rates were twofold higher in OSPM than reference wetlands; chemical SOD exceeded biological SOD for both wetland classes (~90% of total SOD). OSPM-wetland sediments, likely have less microbial activity and more chemical oxidation than reference wetlands. Carbon accrual is necessary for reclaiming Alberta boreal wetlands. Low microbial activity may promote carbon sequestration within OSPM-wetlands but high chemical SOD may limit available oxygen for benthos respiration.

Joshua Martin (M.Sc. 2009) - Full Thesis Text
Thesis Title: The nucleolar organizer of the salivary gland polytene chromosomes as a measure of recent growth in laboratory-reared and field-collected Chironomus spp. (Diptera: Chironomidae) Larvae.

Thesis Abstract: Midge larvae possess giant polytene chromosomes. Genes on these chromosomes undergoing transcription are visible as puffs. The nucleolar organizer (NOR), an especially large puff, shrinks when a larva is stressed. Two feeding experiments were conducted to examine how NOR size changes as a function of Chironomus riparius growth. NOR size was linearly related to an individual’s recent growth rate, independent of its body size.

Chironomids were collected from wetlands constructed with oil sands mine water and tailings (OSPM), and reference wetlands to evaluate the utility of the NOR as a field-based measure of larval growth and condition. Small larvae (< 9mm) did not yield sufficient quality preparations. Five karyotypes were identified, revealing cryptic diversity in the wetlands. NOR size was measured in a single karyotype; no measures were obtained from OSPM-affected wetlands. NOR size has potential as a surrogate growth measure that can facilitate estimation of chironomid secondary production.

Misun Kang (Ph.D. 2009)
Thesis Title: Patterns of biodiversity and co-occurrence of native and nonindiginous species at great lakes coastal margins.

Thesis Abstract:

Studies that assess the ecological processes that allow establishment by a nonindigenous species in the Laurentian Great Lakes can help elucidate general ecological processes. The Great Lakes has such varied habitats that observations of any general patterns in ecological processes, involving both native species and nonindigenous species, likely pertain elsewhere. Studies relating biotic interactions and interaction-neutral processes to invasibility are numerous, but they have been largely inconclusive.

This thesis evaluates hypotheses linking biotic interaction (i.e., richness, evenness, and dominance) and neutral-interaction (i.e., dispersal/propagule pressure) processes of several taxonomic groups (birds, diatoms, fishes, macroinvertebrates, and wetland vegetation) to invasibility at various spatial scales and sample sizes. These hypotheses were assessed using synoptic sample collections from various locations throughout the US Laurentian Great Lakes coastal margins influenced by varying types and levels of anthropogenic disturbance.

I tested hypotheses relating biotic resistance versus habitat suitability to invasion by a nonindigenous amphipod. Results supported the view that biotic facilitation by dreissenid mussels and distribution of suitable habitats better explain the distribution of the nonindigenous amphipod than anthropogenic disturbance and biotic resistance.

I evaluated hypotheses relating richness, evenness, and relative species dominance, to invasibility and the occurrence of native and nonindigenous species using data compiled for various taxonomic groups from several hundred locations along the US coastline of the Laurentian Great Lakes. Across taxonomic groups, trends of native and nonindigenous species distributions were inconsistent with regulation by biotic interaction related processes. Regulation by neutral processes, such as propagule pressure or habitat suitability may better explain patterns Native species distributions were correlated with with habitat suitability and habitat hydrogeomorphology, and ranges reflect biogeographic history. The factors that constrain nonindigenous species are arguably a variation of those that constrain native species distributions, thus indicating that similar factors constrain both native and nonindigenous species.

The general accuracy of these synoptic findings was assessed by comparing biodiversity estimation performance of data resulting from intensive sampling protocols. A method proposed by Olszewski (2004), which is alternative to rarefaction, and statistical estimators for species richness, was also tested. This method uses the evenness component of biodiversity and requires a limited number of samples for estimations. My findings indicated that true biodiversity measures cannot be attained efficiently from surveys. Since such measures are unattainable, interpretation of biodiversity studies would benefit from closer examination of detectable species (i.e., common species) that likely have a stronger impact on community processes, than rare and/or transient species.

Nonindigenous species that become widespread and abundant are likely governed by the same factors that regulate common native species. Ecology would benefit from linking studies of the factors that regulate the distribution and abundances of common species, both native and nonindigenous, and the dynamics between biodiversity and ecosystem properties and processes

Carla Wytrykush Ph.D. Candidate (On leave - 2009)

Thesis Title: Diversity and ecosystem processes and properties in wetland communities: the effects of ecosystem stressors and reclamation challenges.

Project Summary: Decomposition of dead plant material is an integral process providing key nutrients to drive primary productivity in wetlands. How rapidly aquatic plant matter is broken down within a wetland can indicate the potential for productivity and, by extension, the adequate functioning of aquatic ecosystems. In contrast, the sequestration of incompletely decomposed materials ultimately results in organic matter production, potentially supporting the development of fens and bogs. Carla's research examines the effects of four factors on cattail and moss decomposition in constructed and natural wetlands: 1) oil sands process sediments (present/absent); 2) oil sands process water (present/ absent); 3) wetland age (younger vs. older); and 4) sediment organic content (low-unamended/high-amended). Her preliminary results suggest OSPM affected wetlands function similarly to natural wetlands in terms of plant decomposition. An important result from Carla’s project is the evidence that moss growth can occur in OSPM wetlands. This is useful in terms of the development of bogs and fens in the oil sands reclamation landscape.

Lyndon Barr (M.Sc. 2009) - Full Thesis Text
Thesis Title: Influences of tailings water, sediments, macrophytes and detritus on zoobenthic community development in constructed wetlands- Results of a reciprocal transplant study

Thesis Abstract: Wetlands constructed with oil sand process materials are being used by the oil sands mining corporations to reclaim the post-mining landscape. A reciprocal sediment transplant study was conducted to measure effects of sediment, water, plant cover, detritus mass and year-to-year variation on zoobenthic richness, density and relative abundance. Density did not change between wetlands, but the oil sand process water-affected wetland had lower richness than the reference wetland. Zoobenthic relative abundance was influenced by water type, macrophyte density and amount of accumulated detritus in sediment. Zoobenthos density was significantly positively associated with amount of plant cover and detritus combined. Sediment did not directly influence zoobenthic abundance or richness. However, its inhibition of plant percent cover caused an indirect effect.

Jian Zhang (M.Sc. 2008) - Full Thesis Text
Thesis Title: Zoobenthic community composition and Chironomidae (Diptera) mouthpart deformities as indicators of sediment contamination in the Lake Huron-Lake Erie corridor of the Laurentian Great Lakes

Thesis Abstract: Zoobenthos are widely used indicators of ecological quality, integrating changes in habitat condition over time. This thesis investigated community composition and incidence of larval chironomid mouthpart deformities to assess benthic condition in the Lake Huron-Lake Erie Corridor.

To test the "Reference-Degraded Continuum" multivariate approach of zoobenthic community assessment, a series of analyses were used to identify two unique groupings of least-contaminated reference sites, each with characteristic relative abundances of zoobenthic genera and associated habitat features. Statistically
significant negative relationships between biological condition and sediment contamination were found for each group. Indicator taxa were identified.

Six of 43 Chironomidae genera were assessed for mouthpart deformities. Overall incidence of deformities varied from 0.57% to 5.88% among zones. Only Chironomus exhibited significant among-zone variation, reflecting gross levels of sediment contamination.

The combined use of community and individual indicators was more diagnostic of benthic habitat quality than use of either approach alone.

Leanne Baker (M.Sc. 2007) - Full Thesis Text
Thesis Title: The effects of petroleum coke amendments on macrophytes and aquatic invertebrates in northern Alberta, Canada constructed wetlands

Thesis Abstract: The oil-sands operators of Fort McMurray, Alberta produce six million tonnes of petroleum coke per year. The use of coke to stabilize clay-dominated mine tailings in constructed wetlands is being studied in landscape reclamation. We studied 'in situ' effects of petroleum coke amendments placed in three wetlands constructed with different materials over two years. Coke amendments did not significantly increase concentrations of trace metals in sediment pore waters or associated biota in plots. Growth of resident macrophyte species was not prohibited by coke amendments. Coke plots in a reference wetland contained fewer stress-intolerant invertebrates, than reference plots, likely due to avoidance of coke substrates. Adding peat reduced 'Chara' cover and biomass in the reference wetland, but had no impact on plants or invertebrates in the wetlands with little organic content. Overall, local coke amendment effects were detected in a reference wetland but not in two wetlands constructed with other oil sands process materials.


Christine Daly (M.Sc. 2007) - Full Thesis text
Thesis Title: Carbon sources, microbial community production, and respiration in constructed wetlands of the Alberta, Canada oil sands mining area.

Thesis Abstract: Carbon sources, microbial community production, and respiration were determined in 9 wetlands in northeastern Alberta subject to oil sands mining. A stable isotope mixing model estimated the proportion of carbon sources (primary production, sediment and petroleum) assimilated by microbes. The proportions of petroleum-derived carbon from oil sands process material (OSPM) affected wetlands ranged from 62-97%. Bacterioplankton production was quantified by monitoring 3 H-leucine incorporation into bacterial proteins. Production and methanogenesis were inhibited by sulphate and/or salinity. Amending wetland sediments with topsoil, a reclamation strategy, did not affect bacterial production, or stimulate decomposition. Unvegetated wetland sediments were small net exporters of C (0.61 mg/m²/d) and do not appear to be on a trajectory to becoming net sinks in these early stages of development. Overall, microbial functional processes in OSPM-affected wetlands are markedly different from processes in reference constructed wetlands of equivalent age and do not correspond to those in a natural wetland.


Yakuta Bhagat (M.Sc. 2005) - Full Thesis Text
Thesis Title: Fish indicators of anthropogenic stress at Great Lakes coastal margins

Thesis Abstract: Two commonly applied approaches to assessing the health of an aquatic habitat are the multimetric index of biotic integrity (IBI) and the multivariate approach. Fish community composition and local environmental conditions were measured at 143 sites across the entire U.S. coastline between 2002 and 2003, using overnight-set fyke nets (a large collaborative study to develop environmental indicators at Great Lakes coastal margins (GLEI)). Of these sites, data from 55 wetlands were used in an attempt to develop IBIs for the Northern Great Lakes (NGL) ecoregion and the Erie and Ontario (EOL) ecoregion. Candidate metrics were evaluated with respect to agricultural stress measured at drainage basin and immediate watershed topographical scales. An IBI could be developed only for the NGL ecoregion, based on a criterion requiring inclusion of at least 4 metrics representing attributes of a natural habitat. Fish community metrics in the NGL ecoregion varied more strongly with stress at the larger segment-shed scale. A further test of the IBI approach was done using independently developed IBIs for Typha and Scirpus aquatic plant zones of Great Lakes coastal wetlands (Uzarski et al. 2005). IBI scores were calculated for 32 wetlands with dominant Typha and Scirpus vegetation using data collected through the GLEI project. The results indicated that both the Typha and Scirpus IBI were selectively responsive to anthropogenic stressors. The Typha IBI varied most significantly as a function of population density-related stress and the Scirpus IBI most strongly reflected agriculture-related stress.


André Bachteram (M.Sc. 2004) (Coadvisor: Dr. Trefor Reynoldson) - Full Thesis Text
Thesis Title: Bioturbation by Hexagenia larvae (Ephemeroptera: Ephemeridae) and its implications for sediment suspension in Lake Erie

Thesis Abstract: Burrowing activities of aquatic benthic organisms can influence sediment suspension and nutrient cycling. The burrowing mayfly Hexagenia is a dominant benthic organism in western Lake Erie, and Hexagenia bioturbation can potentially influence water quality and other benthic organisms. Using laboratory experiments, I determined bioturbation-induced sediment suspension rates of fine Lake Erie sediment caused by Hexagenia larvae of varying body lengths (13-28 mm) at densities of 70-1111 larvae/m² and water temperatures ranging from 10-25°C. Bioturbation rates (sediment suspension, g/m²/h) were estimated by nonlinear regression from measurements of suspended sediment concentrations in jars, taken twice-daily for 14 d. Sediment settling rates were also estimated from twice-daily measurements of suspended sediment concentrations collected for an additional 18 d in the surface water from the bioturbation experiments.


MiSun Kang (M.Sc. 2003) - Full Thesis Text
Thesis Title: The relationship between athropogenic disturbance and the distribution of a nonindigenous species, Echinogammarus ischinus Stebbing, 1989 (Amphipoda: Gammaridae), at Great Lakes Coastal Margins

Thesis Abstract: Invasive species are becoming increasingly common components of Great Lakes zoobenthic communities. Elton (1958) proposed that biotic resistance against exotic species establishment is greater in intact communities than in those disturbed by human activities. However, Baltz and Moyle (1993) suggested that if abiotic conditions are appropriate, invasion is likely, regardless of the biota already present. I tested these hypotheses by investigating the distribution of Echinogammarus ischnus Stebbing, 1898, an exotic amphipod, at U.S. Great Lakes coastal margin sites influenced by varying degrees of anthropogenic stress. Thirty-nine sites supporting Gammarus fasciatus Say, 1818, a common amphipod with habitat preferences similar to Echinogammarus ischnus, were evaluated (out of a total of 74 sites sampled across the entire U.S. Great Lakes coastline). A highly significant association was detected between Echinogammarus ischnus and Gammarus fasciatus (Yates corrected χ² = 7.94, d.f. = 1, p = 0.020, n = 74), consistent with the expectations of Baltz and Moyle's hypothesis.


Christel Leonhardt (M.Sc. 2003) - Full Thesis Text
Thesis Title: Zoobenthic Succession in Constructed Wetlands of the Fort McMurray Oil Sands Region: Developing a Measure of Zoobenthic Recovery

Thesis Abstract: This study investigated the effect of oil sands process material (OSPM) on the zoobenthic community of constructed wetlands in the Fort McMurray oil sands region. The unique characteristics of OSPM-affected wetlands may modify the successional trajectory of invertebrate communities compared to that of high or low-conductivity reference wetlands. The zoobenthic community of 31 wetlands, aged 0 to 30 years, was simultaneously sampled, allowing inference into the chronological sequence of change that results with wetland succession. Wetlands were categorised 'a priori' into one of three classes: low conductivity (<700 µS/cm) or high conductivity (700-2,500 µS/cm) reference wetlands or OSPM-affected wetlands (700-4,000 µS/cm) containing tailings and/or water from bitumen extraction. Invertebrate communities in each wetland were assessed using core, artificial substrate, and sweep net sampling methods. Principal components analysis and discriminant function analysis were used to classify each OSPM-affected wetland as being 'equivalent to young' or 'equivalent to mature' reference wetlands. Restoration of mined areas to pre-mining conditions of diversity and abundance of habitat types, using wetlands as a component of a reclamation strategy, is a viable option.


Kevin Ganshorn (M.Sc. 2002)
Thesis Title: Secondary Production, Trophic Position and Potential for Accumulation of Polycyclic Aromatic Hydrocarbons in Predatory Diptera in Four Wetlands of the Athabasca Oil Sands, Alberta, Canada

Thesis Abstract: Larvae of aquatic Diptera are important predators in fishless wetlands of northeast Alberta. Annual production was estimated for benthic (Chironomidae: Tanypodinae) and pelagic (Chaoboridae: Chaoborus) dipteran populations in four wetlands in surface-mined areas of the Athabasca oil sands, two of which received oil sands mine process material (OSPM; containing polycyclic aromatic hydrocarbons (PAHs)), and two of which were reference wetlands. The structure of benthic and pelagic food webs was estimated by measuring stable carbon and nitrogen isotopes. Stable nitrogen isotopes were also used to determine trophic levels of Tanypodinae and Chaoborus in order to determine their potential to bioaccumulate PAHs. Annual production was estimated along with total PAH body burdens to determine the potential for biomass and PAH export by the emergent adult insects. Tanypodinae production (1.55 - 28.77 g/m²/y) consistently exceeded Chaoborus production (0.009-0.372 g/m²/y). Chaoborus trophic position estimates were consistently greater than estimates for Tanypodinae, suggesting greater PAH bioaccumulation potential for Chaoborus. Tanypodinae had greater potential to export PAHs (1.86-37.1 mg/m²/y) than Chaoborus (0.011 - 0.45 mg/m²/y) due to greater production and PAH body burdens.


Erin Swansburg (M.Sc. 2000) (Coadvisor: Dr. Wayne Fairchild) - Full Thesis Text
Thesis Title: Effects of Trace Metal Enrichment in Cobble Streams and Rivers on the Aquatic Midge (Diptera: Chironomidae)

Thesis Abstract: Chironomidae (Diptera) are commonly used as indicators of environmental degradation. This study examined the effects of mine drainage on chironomid assemblages in northeastern New Brunswick rivers. At mine drainage receiving sites, significantly elevated concentrations of metals in water (Ba, Fe, K, Mn and Zn; p < 0.05) and in periphyton (Cd, Co, Cu, Mn, Pb and Zn; p < 0.002) were detected. Concentrations in periphyton were 10-100 times higher than in water, suggesting that metal uptake from diet may be a more important source of metals for primary consumers than surrounding water. Chironomid composition was significantly different at mine drainage receiving sites than at reference sites. To assess the effects of metal enriched periphyton on aquatic invertebrates downstream of metal mining facilities, periphyton was collected at mine drainage receiving (MIN) and reference (REF) sites in northeastern New Brunswick rivers and fed to Chironomus riparius in a 10-d bioassay. These results suggest that primary consumers feeding on periphyton are at risk of significant mortality and reduced growth, compromising the viability of most metal intolerant populations. Consequently, metal enrichment of periphyton could explain observed differences in chironomid communities of mine drainage receiving rivers.


Jocelyn Gerlofsma (M.Sc. 1999) - Full Thesis Text
Thesis Title: The Effects of Anoxia and Temperature on the Development and Survival of Hexagenia (Ephemeroptera: Ephemeridae) embryos, and implications for Western Lake Erie

Thesis Abstract: Benthic Hexagenia embryos can be exposed to anoxic hypolimnetic water or can become buried in the sediment. In western Lake Erie, periodic anoxia resulting from transient stratification has eradicated Hexagenia populations. The ability of embryos to survive anoxia and hatch when normoxic conditions return would allow the population to recover after an anoxic event. I studied the survivorship and development of Hexagenia embryos at various developmental stages maintained in anoxic conditions for different time periods, at different temperatures. In 1996, Hexagenia nymphs were absent from several regions in western Lake Erie. I collected sediment cores from two such areas and two other areas supporting nymphs. I studied the effects of hypoxia on embryos by adding eggs to the sediment cores. The results of my studies are that Hexagenia eggs would be able to survive periods of anoxia at different temperatures over its embryological development. This would allow eggs to repopulate an area after a period of epibenthic anoxia that would eradicate the nymphs.


Mark Whelly (M.Sc. 1999) - Full Thesis Text
Thesis Title: Aquatic Invertebrates in Wetlands of the Oil Sands Region of Northeast Alberta, Canada, with Emphasis on Chironomidae (Diptera)

Thesis Abstract: This thesis describes the effects of oil sands process waters (OSPW) on the benthic macroinvertebrate component of wetland ecosystems through assessment of biological responses at various levels of organization. Comparison of the macroinvertebrate communities among OSPW-affected wetlands and environmentally-similar reference wetlands indicated an insignificant trend of reduced taxonomic richness and abundance. Also, the general benthic macroinvertebrate community and specifically the chironomid community showed differences in community composition between OSPW and reference wetlands, in terms of the presence and relative abundances of dominant taxa. The incidence of chironomid mouthpart deformities, a biomarker of teratogenicity, was low at three pairs of reference and OSPW wetlands. Similarly, there was no evidence to show that OSPW induces mouthpart deformities. However, growth and survival were significantly reduced in both lab and field-derived C. tentans larvae exposed to higher concentrations of OSPW.


George Pardalis (M.Sc. 1997) - Full Thesis Text
Thesis Title: A comparison of the responses of benthic invertebrate individuals, populations, and communities to creosote contamination, with emphasis on Chironomidae (Diptera)

Thesis Abstract: Environmental management strategies include the use of aquatic biota for environmental monitoring and assessment. There exists a need for reliable early warning indicators of impending environmental degradation. This study evaluated the toxicity of creosote as indicated by a 48-h acute toxicity sediment bioassay and various measures of the benthic invertebrate community and chironomid populations in artificial ponds, to which creosote was added. The study also evaluated the potentially useful early warning indicator, chironomid morphological deformities, in determining a toxic response. In the laboratory, a 48-h spiked-sediment toxicity test was conducted by placing 4th instar Chironomus riparius Meigen larvae in formulated sediment (sand, sculptor's clay, potting soil) spiked with creosote (a PAH mixture). The estimated median lethal concentration (LC50) value was 437 µg creosote/g sediment. A toxicity study was conducted in 10,000 L artificial ponds (mesocosms) located at the Turfgrass Institute, University of Guelph, Guelph, Ontario. Ponds received a single application of creosote to produce a logarithmic series of nominal concentrations ranging from 0.053 µL/L to 100 µL/L water. Four community attributes (total invertebrate density, family richness, chironomid density, chironomid generic richness) and two population measures (Procladius density, Psectrocladius density) were tabulated and regressed against creosote concentration. Combined triplicate samples of Procladius larvae from each pond were examined for deformities of various cephalic structures (ligula, paralabial combs, and mandibles).


Andreas Winter (M.Sc. 1994)
Thesis Title: Influence of Oxygen Stress, Temperature and Density on the Growth and Survivorship of Hexagenia nymphs (Ephemeroptera: Ephemeridae)

Thesis Abstract: Burrowing mayflies of the genus Hexagenia are sensitive to conditions of low dissolved oxygen, and their population has been proposed as an ecosystem objective for assessing the recovery from eutrophication of mesotrophic lakes in which they were once abundant. While acute oxygen tolerance limits are known for Hexagenia nymphs, effects of prolonged exposure to sublethal levels of hypoxia have not been previously studied. I conducted 21-day laboratory experiments examining hypoxic stress in relation to different densities (1, 5, 10 and 20 individuals per 70 cm²), and in relation to a range of temperatures (4-20°C) characteristics of their Great Lakes habitat. Increasing density had a significant negative effect on survival in experiments with low overall survivorship. When survivorship was high, the interaction of oxygen stress (2.0-4.3 mg/L (O₂)) and density significantly influenced survival, but density alone did not. Density was negatively correlated with growth under oxygen stressed conditions in cultures that had high overall survivorship, and positively correlated with growth in cultures that had low survivorship. Survival of nymphs increased with oxygen concentration up to an asymptote at approximately 7-8 mg/L. Survivorship increased with temperature up to an asymptote at approximately 9.5°C. Higher temperatures aggravated the effects of hypoxia on survivorship. Oxygen and temperature together explained 89% of the variability in survivorship and 71% of the variability in growth among experiments. Within experiment, larger nymphs generally had higher survivorship than smaller nymphs, and this trend exhibited a slight positive correlation with temperature. My data predict a gradual increase for survivorship and total biomass of nymphs in western Lake Erie. Combined with in situ monitoring of oxygen and temperature conditions, these results should enable us to anticipate the time to reestablishment of the Hexagenia population in mesotrophic habitats.
 

Lori Hudson (M.Sc. 1994)
Thesis Title: Chromosomal and morphological abnormalities in larval midges (Diptera: Chironomidae) as indicators of chronic sediment toxicity. 

Elizabeth Hanes (M.Sc. 1992)
Thesis Title: Life History Characteristics and Size Variation of the Burrowing Mayfly Hexagenia (Ephemeroptera: Ephemeridae): Maternal vs. Environmental Constraints

Thesis Abstract: There is tremendous size variation within both laboratory and field populations of the mayfly Hexagenia. I studied the size variation in adults (imagoes) of this mayfly collected in the summers of 1989 and 1990 from Lake St. Clair, Southwestern Ontario (42°20'N; 82°57'W). Additionally, I examined the influence of endogenous factors (egg hatching, egg diapause, maternal size) on size and survivorship of larval Hexagenia. Female imagoes collected early in the emergence period were significantly larger than females collected later in the summer. There was low incidence of parthenogenesis (<5%), egg diapause (<0.01%) and viability of eggs produced through interspecific mating (0%) in the laboratory. Egg size of H. limbata was negatively correlated with collection date. Although egg size did vary among female sizes, there was no clear relationship between egg size and maternal size. Maternal size was negatively correlated with larval size, after 40 d growth. Maternal size and maternal size² were correlated with per cent larval survival. Maternal parents exhibiting mean body length produced larvae with the highest survivorship after 40 d growth. The length of incubation (days) required for egg hatch was negatively associated with per cent larval survival (40 d) but was positively correlated with larval size (80 d). Of sediments examined from six different waterbodies, Saginaw Bay sediment provided larvae with the best survivorship and the largest size, and when given a choice, larvae selected that sediment type. Subsequently, I developed a standard sediment (STND-3) that mimiced the particle size distribution and organic content of Saginaw Bay sediment.
 

Sherry Beckett (M.Sc. 1992)
Thesis Title:  Microhabitat selection and biotic interactions as factors influencing spatial dynamics among larval black flies (Diptera: Simuliidae).

Mark Dunnigan (M.Sc. 1991)
Thesis Title: Field experiments on the relationship between periphyton and macroinvertebrate distribution in streams.

Donna Bedard (Coadvisor Dr. G. Douglas Haffner)  (M.Sc. 1990)
Thesis Title: Factors Influencing the Bioaccumulation of Chlorinated Hydrocarbons by Hexagenia nymphs (Ephemeroptera: Ephemeridae)


Zsolt Kovats (M.Sc. 1990)
Thesis Title: Adult Aquatic Insects as Biomonitors of Organochlorine Contamination in Freshwater Habitats

Thesis Abstract: The bottom-dwelling larvae of aquatic insects are useful indicators of organochlorine (OC) contamination in aquatic habitats. However, these animals are often difficult to collect in numbers sufficient for contaminant analysis by gas chromatography. Winged, night-active adults retain accumulated contaminants, and can be collected in large numbers using light traps. Methodology was developed and evaluated for collection and analysis of adult caddisflies (Trichoptera) and mayflies (Ephemeroptera) for monitoring OC contaminant levels in freshwater habitats. Insects were collected using light traps from Great Lakes connecting channels and reference sites, and samples were analyzed for contaminants. Contaminant concentrations in samples of adult insects broadly corresponded to reported levels of chlorinated organic contaminants in sediments of the rivers and lakes of their origin. Spatial pattern of contaminants among insect samples collected along the length of rivers reflected the pattern documented for sediments in all Great Lakes connecting channels. Contaminant concentrations in insects varied with time in the Detroit and St. Clair rivers. Significant differences in contaminant concentration were found in animals of different species from the same location. Light-trapped adult aquatic insects are well suited for use in long-term biomonitoring programs, and for preliminary or synoptic studies of aquatic contamination in previously unsurveyed areas.