Northwestern Ontario Research Articles

High Incidence of Invasive Group A Streptococcus Disease Caused by Strains of Uncommon emm Types in Thunder Bay, Ontario, Canada.

An outbreak of type emm59 invasive group A Streptococcus (iGAS) disease was declared in 2008 in Thunder Bay District, Northwestern Ontario, 2 years after a countrywide emm59 epidemic was recognized in Canada. Despite a declining number of emm59 infections since 2010, numerous cases of iGAS disease continue to be reported in the area. We collected clinical information on all iGAS cases recorded in Thunder Bay District from 2008 to 2013. We also emm typed and sequenced the genomes of all available strains isolated from 2011 to 2013 from iGAS infections and from severe cases of soft tissue infections. We used whole-genome sequencing data to investigate the population structure of GAS strains of the most frequently isolated emm types. We report an increased incidence of iGAS in Thunder Bay compared to the metropolitan area of Toronto/Peel and the province of Ontario. Illicit drug use, alcohol abuse, homelessness, and hepatitis C infection were underlying diseases or conditions that might have predisposed patients to iGAS disease. Most cases were caused by clonal strains of skin or generalist emm types (i.e., emm82, emm87, emm101, emm4, emm83, and emm114) uncommonly seen in other areas of the province. We observed rapid waxing and waning of emm types causing disease and their replacement by other emm types associated with the same tissue tropisms. Thus, iGAS disease in Thunder Bay District predominantly affects a select population of disadvantaged persons and is caused by clonally related strains of a few skin and generalist emm types less commonly associated with iGAS in other areas of Ontario.

From marginalization to self-determined participation

This article discusses, from an anthropological perspective, the utilization of digital infrastructures and technologies in the geographical and sociocultural contexts of indigenous Northwestern Ontario, Canada. By introducing the case of the Keewaytinook Okimakanak Kuh-ke-nah Network (KO-KNET) it analyses first how digital infrastructures not only connect First Nations people and communities but also enable relationships between local communities and non-indigenous institutions. Second, and by drawing on KO-KNET’s homepage service MyKnet.org, it exemplifies how people appropriate digital technologies for their specific needs in a remote and isolated area. KO-KNET and its services facilitate First Nations’ self‑determined participation to regional, national, and even global ICT connectivity processes, contributing thus to the “digital de-marginalization” of Northwestern Ontario’s remote communities.

A simulation-based optimization approach to integrated inventory management of a sawlog supply chain with demand uncertainty

This paper develops a simulation-based optimization supply chain model for supplying sawlogs to a sawmill from a forest management unit. The simulation model integrates the two-way flow of information and materials under the stochastic demand of the sawmill production unit. The dynamic optimization model finds the optimum inventory policy (s, S) that minimizes the total inventory cost for the three supply chain agents — sawmill storage, merchandizing yard, and forest management unit. The model is used to analyze a real sawmill case study in northwestern Ontario, Canada. It was found that the merchandizing yard absorbs shocks of uncertain demand from the sawmill production unit and reduces idle time, but it increases the total cost of the supply chain by $11 802 (about 42%). The optimized model predicts that only 3.5 days of inventory is required at the sawmill storage. The simulation-based optimization supplier model will help in decision-making at the tactical and operational level in the forest products industry supply chain through a two-way flow of information and materials.

A study of institutional origins and change in a Canadian urban commons

Kenora is a small city located in northwestern Ontario, Canada. The study presented here focuses on Tunnel Island, 300 acres of forested land adjacent to Kenora’s downtown. The island is used and valued by both city residents and members of three nearby Ojibway nations. As a multiple-use, common-pool resource accessed by different groups for a range of non-extractive activities, the site has become an experiment in multicultural commons governance, and presents an excellent opportunity to examine the origins and development of institutions for managing collective environmental resources in an urban setting. Using participant observation, internet- and field-based user surveys, and semi-structured interviews, our research finds that grassroots ‘governance’ of the site is emerging through subtle processes of individual and social construction, with the strategies and norms (codes of conduct) employed by users providing relative harmony on the trails, which suggests functioning commons institutions. Nevertheless, values-based and epistemic tensions exist among users, pointing to governance challenges for planned joint management of the site, and specifically the need to develop formal, legitimate, and yet flexible and inclusive arrangements that can operate in conjunction with the social practice of existing users.

Life cycle environmental impact assessment of biochar-based bioenergy production and utilization in Northwestern Ontario, Canada

Biochar-based bioenergy production and subsequent land application of biochar can reduce greenhouse gas emissions by fixing atmospheric carbon into the soil for a long period of time. A thorough life cycle assessment of biochar-based bioenergy production and biochar land application in Northwestern Ontario is conducted using SimaPro® Ver. 8.1. The results of energy consumption and potential environmental impact of biochar-based bioenergy production system are compared with those of conventional coal-based system. Results show that biochar land application consumes 4847.61 MJ per tonne dry feedstock more energy than conventional system, but reduces the GHG emissions by 68.19 kg CO2e per tonne of dry feedstock in its life cycle. Biochar land application improves ecosystem quality by 18 %, reduces climate change by 15 %, and resource use by 13 % but may adversely impact on human health by increasing disability adjusted life years by 1.7 % if biomass availability is low to medium. Replacing fossil fuel with woody biomass has a positive impact on the environment, as one tonne of dry biomass feedstock when converted to biochar reduces up to 38 kg CO2e with biochar land application despite using more energy. These results will help understand a comprehensive picture of the new interventions in forestry businesses, which are promoting biochar-based bioenergy production.

Apparent extirpation of prey fish communities following the introduction of Northern Pike (<em>Esox lucius</em>)

We examined the long-term effects on prey fish communities of introducing Northern Pike (Esox lucius), a top predator fish, into small, Boreal Shield lakes lacking natural piscivore populations. During 1987–1994, Northern Pike were introduced into Lakes 110, 221, and 227 in the Experimental Lakes Area in northwestern Ontario, Canada. In Lake 227, prey fish were undetectable three years after the addition of Northern Pike. Although Northern Pike were removed from the lake by 1996, multiple independent visual and trapping surveys have yielded no evidence of any fish in Lake 227 since then. In 1994–1995, 85% of the Northern Pike were removed from Lake 221. In 2012, despite intensive sampling efforts using baited minnow traps, fyke nets, trap netting, gill netting, angling, and visual observation, no forage fish of any species was observed or caught in Lake 110 or 221. In all three lakes where Northern Pike were added, prey fish populations were extirpated or too small to detect. In Lake 221, we estimated the current population of Northern Pike to be 49 ± 37, a 59% decrease since 2000 when prey fish were still present. The mean total length and body condition of Northern Pike in Lake 221 had not changed since the prey community collapsed. Our findings suggest that the introduction of Northern Pike into lakes without natural piscivore populations has long-lasting effects on fish community structure, to the detriment of both Northern Pike and prey fish populations.Note: an erratum for this article was published in the subsequent issue, and is attached to the end of this article's pdf. Table 2 had not been justified properly; the revised table corrects this issue.

Length of Stay and Achievement of Functional Milestones in a Rural First Nations Population in Northwestern Ontario during Acute-Care Admission after Total Hip Replacement: A Retrospective Chart Review.

To understand the postoperative acute-care physiotherapy course for First Nations people returning after total hip replacement (THR) to remote communities with limited rehabilitation services and to evaluate length of stay and attainment of functional milestones after THR to determine to what extent an urban-based clinical pathway is transferrable to and effective for First Nations patients in a rural setting. Data were collected retrospectively by reviewing charts of patients who underwent THR in the Northwest Ontario catchment area from 2007 through 2012. For the 36 patient charts reviewed, median length of stay (LOS) at the Sioux Lookout Meno Ya Win Health Centre (SLMHC) was 7.5 days (range 2-335); median LOS from time of surgery at the regional hospital (Thunder Bay Regional Health Centre) to discharge from SLMHC was 13.5 days; and median time for mobilizing and stairs was 9 days (range 1-93). Commonly accepted urban clinical pathways are not a good fit for smaller rural hospitals from which First Nations patients return to remote communities without rehabilitation services. LOS in a rural acute-care facility is similar to LOS in an urban rehabilitation facility.

Colonial legacy and the experience of First Nations women in cervical cancer screening: a Canadian multi-community study

Regular Papanicolaou (Pap) screening has dramatically reduced cervical cancer incidence in Canada since the 1950s. However, Indigenous women’s rates of cervical cancer remain disproportionately high, a factor which is not acknowledged in national media or in educational materials reporting Canada’s new cervical cancer screening guidelines. Here, we present findings from a cervical cancer screening initiative in Northwestern Ontario. Based on participatory action research, we worked with 10 First Nations communities in the Robinson Superior Treaty area to increase awareness of cervical cancer risk, develop culturally sensitive tools for screening and education and test the efficacy of human papillomavirus (HPV) self-sampling as an alternative to Pap cytology. We conducted 16 interviews with health care professionals and 9 focus groups with 69 women from the communities. A central theme for both health care providers (HCPs) and community members was the colonial legacy and its influence on women’s experiences of cervical cancer screening. This was evidenced by a strong sense of body shyness, including shame related to sexuality and sexually transmitted infections, concerns about confidentiality in clinical encounters and distrust or caution around HCPs. Reaffirming women’s traditional caregiving and educational roles, enhancing mother and daughter communication, improving cultural sensitivity in health care and education and adoption of HPV self-sampling to increase women’s privacy and control of the cervical cancer screening experience were endorsed. We argue that education and screening initiatives must reflect the cultural preferences of Indigenous women, empowering them to take control of their experiences of health and body in cervical cancer screening.

Introducing Shared Mental Health Care in Northwestern Ontario: An Analysis of Changing Referral Patterns of Primary Care Providers

This study describes a shared mental health care (SMHC) model introduced in Northern Ontario and examines how its introduction affected primary care provider (PCP) mental health referral patterns. A chart review examined referrals (N = 4,600) from 5 PCP sites to 5 outpatient community mental health services from January 2001 to December 2005. PCPs with access to SMHC made significantly more mental health referrals (p < 0.001). Two demographically similar PCPs were then compared, one co-located with SMHC. Referrals for depression to non-SMHC mental health services were 1.69 times more likely to be from the PCP not co-located with SMHC (p < 0.001). Findings suggest SMHC increases access to care and decreases demand on existing mental health services.

New records of the Lyme disease bacterium in ticks collected from songbirds in central and eastern Canada

This study highlights the collection of ticks from wild-caught birds in central and eastern Canada. Using polymerase chain reaction (PCR), 32 (33%) of 98 Ixodes species ticks tested were positive for the Lyme disease bacterium, Borrelia burgdorferi sensu lato (s.l.) Johnson, Schmid, Hyde, Steigerwalt, and Brenner (hereafter B. burgdorferi). Immature blacklegged ticks, Ixodes scapularis Say, which are competent vectors of B. burgdorferi, constituted the predominant Ixodes species tick collected from parasitized songbirds; specifically, 31(35%) of 89 I. scapularis nymphs were positive for B. burgdorferi. Notably, we report the first B. burgdorferi-positive I. scapularis (nymph) on a migratory passerine in Prince Edward Island; this is the first record of a tick on a bird in this maritime province. First-time records of B. burgdorferi-infected, I. scapularis nymphs on passerines in northwestern Ontario include rose-breasted grosbeak, Pheucticus ludovicianus (Linnaeus), eastern bluebird, Sialia sialis (L.), and indigo bunting, Passerina cyanea (L.). Similarly, we furnish a new host record in Canada for an I. scapularis (nymph) on a worm-eating warbler, Helmitheras vermivorus (Gmelin); this engorged nymph tested positive for B. burgdorferi. We document the first recorded collection of a B. burgdorferi-infected Ixodes muris Bishopp and Smith (female) on a songbird in Ontario. We provide the first account of a live culture of B. burgdorferi from an I. scapularis (nymph) collected from a brown-headed cowbird Molothrus ater (Boddaert) in Manitoba. We make available new host records for I. scapularis on a clay-coloured sparrow Spizella pallida (Swainson) and a Gambel’s white-crowned sparrow Zonotrichia leucophrys gambelii (Nuttall). An I. scapularis on a songbird during southward autumn migration in northwestern Ontario is a first record reported. As well, we document the first-ever account of a reptile-associated tick, a nymph of Amblyomma sabanerae Stoll, on a veery Catharus fuscescens (Stephens) in northwestern Ontario. Migratory songbirds play an integral role in the wide dispersal of B. burgdorferi-infected ticks, especially during northward spring migration. Clinicians need to be aware that people can be bitten by B. burgdorferi-infected ticks released by songbirds across Canada.

Abstract 19: Epidemiologic Surveillance of Kawasaki Disease in Manitoba and Northwestern Ontario 2000-2010

Objective: The purpose of this study is to determine the incidence of persistent coronary artery sequelae due to KD between the First Nation/Metis (FN/M) and non First Nation children (n-FN) in the province of Manitoba and Northwestern Ontario, Canada. Methods: This is a 10-year (2000-2010) retrospective chart review study of all patients < 18 years of age identified with KD and persistent coronary artery aneurysms. The data was obtained from the Children’s Hospital of Winnipeg medical records and the Electronic Echocardiography data based at the Variety Heart Centre. Results: A total of 103 children and adolescents with KD and with at least 3 echocardiography studies were enrolled. Complete or incomplete presentation of KD was determined according to the fulfillment for the disease classic criteria on diagnosis. Age at diagnosis ranged between 2 months to 4 years (median 0.5 years) with 2 patients diagnosed during their early infancy (age< 90 days). The median follow up period was 4 years (1.3 to 6.3 years). Persistent coronary artery aneurysms were detected in 10 children (M/F ratio 3:1). Nine (9) of the studied subjects account for the FN/M children group and the remaining 1 is of Asian origin. We observed no n-FN children with permanent cardiac sequelae secondary to KD. Conclusion: There is a significantly higher occurrence of permanent coronary artery lesions due to KD among the FN/M children in the province of Manitoba and Northwestern Ontario. However, this study does not imply direct association of any risk factor, which might be related with our findings. Socio-environmental or even genetic factors might contribute to these findings. Nevertheless, these speculations are beyond the scope of this study. We suggest that a strategy of early, diagnosis and treatment of KD based on the latest AHA guidelines, when we deal with patients of these ethnic/racial groups, should be implemented.

Composition of native crayfish assemblages in southern Ontario rivers affected by rusty crayfish (Orconectes rusticus Girard, 1852) invasions – implications for endangered queensnake recovery

Orconectes rusticus (rusty crayfish) is an aggressive and prolific aquatic invader. Where introduced, it has caused dramatic ecosystem changes, including the replacement of native crayfishes. In Canada, it was first reported in Lake of the Woods in northwestern Ontario and a small number of south-central Ontario lakes during the 1960s. It has subsequently spread to other regions of the province. Its current expansion into southwestern Ontario rivers presents an unknown risk to the endangered queensnake (Regina septemvittata), an obligate feeder on freshly molted crayfish. We sampled 99 river sites across southern Ontario to: (i) describe crayfish assemblages within river reaches currently occupied by Queensnake; and, (ii) characterize the impact of O. rusticus on native crayfish assemblages. O. rusticus was caught at 41% of sites sampled, and was the only species at 24% of sites. The abundance, richness, and within-site distribution of native crayfishes were all significantly lower at sites with O. rusticus. Within the distribution of queensnake, crayfish assemblages were almost entirely dominated by O. propinquus, with O. rusticus being absent. However, O. rusticus was found along the lower Speed River, where only one dam separates it from Grand River queensnake populations. Given its past spread, O. rusticus will likely be introduced into areas used by queensnake and replace O. propinquus (the primary prey of queensnake). The adaptability of queensnake to prey upon non-native crayfish is unknown and requires investigation.

Mid-day temperature variation influences seasonal habitat selection by moose

We tracked 122 female moose in northwestern Ontario, Canada, using global positioning system (GPS) radio-collars between 1995 and 2001. We used step-selection functions (SSF) to evaluate changes in moose habitat selection as a function of temperature across seasons (summer and winter), stand types, and stand heights. We obtained mean activity levels of moose within stand types and across seasons from motion sensors in the collars. Selection increased for aquatic stand types as a function of temperature across both summer and winter. Selection for stand height was also temperature-dependent, with tall stands being most favored at warm temperatures and least favored at cold temperatures. Moose activity levels increased slightly at higher temperatures during the winter but were mostly constant, whereas summer activity declined significantly with increasing temperature. Seasonal activity levels were mostly constant within habitats, but activity was consistently higher in aquatic habitats compared to woody habitats, with the highest mean activity levels observed when moose were located in open water and marshes during the summer. Our findings corroborate the work of others that moose primarily select habitat based on documented foraging requirements, whereas they may alter mid-day selection for specific stand types providing thermal cover under varied temperatures, indicating a behavioral response to thermoregulatory needs. Increased activity levels at low summer temperatures, and in habitats found to provide thermal cover, support the conclusion that moose may alter their activity to alleviate heat stress, and that temperature-mediated changes in habitat selection may facilitate otherwise energetically costly behavior (e.g., movement). © 2015 The Wildlife Society.

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

Abstract. Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number–size distributions in climate model inventories lead to uncertainties in the CCN (cloud condensation nuclei) concentrations and forcing estimates derived from these models. The BORTAS-B (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellite) measurement campaign was designed to sample boreal biomass-burning outflow over eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size distribution of aged biomass-burning emissions (aged ~ 1–2 days) from boreal wildfires in northwestern Ontario. The composite median size distribution yields a single dominant accumulation mode with Dpm = 230 nm (number-median diameter) and σ = 1.5, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios (ΔOA / ΔCO) along the path of Flight b622 show values of 0.09–0.17 μg m−3 ppbv−1 (parts per billion by volume) with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA (organic aerosol) production/evaporation within the aged plume over the sampling period (plume age: 1–2 days), though it does not preclude OA production/loss at earlier stages. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the ΔOA / ΔCO enhancement ratios. We estimate that the young-plume median diameter was in the range of 59–94 nm with modal widths in the range of 1.7–2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in the plume dilution rates.

Localization and seasonal variation of blue pigment (sandercyanin) in walleye (Sander vitreus)

Several fish species, including the walleye (Sander vitreus), have “yellow” and “blue” color morphs. In S. vitreus, one source of the blue color has been identified as a bili-binding protein pigment (sandercyanin), found in surface mucus of the fish. Little is known about the production of the pigment or about its functions. We examined the anatomical localization and seasonal variation of sandercyanin in S. vitreus from a population in McKim Lake, northwestern Ontario, Canada. Skin sections were collected from 20 fish and examined histologically. Mucus was collected from 306 fish over 6 years, and the amount of sandercyanin was quantified spectrophotometrically. Sandercyanin was found solely on dorsal surfaces of the fish and was localized to novel cells in the epidermis, similar in appearance to secretory sacciform cells. Sandercyanin concentrations were significantly higher in fish collected in summer versus other seasons. Yellow and blue morphs did not differ in amounts of sandercyanin, suggesting that the observed blue color, in fact, arises from lack of yellow pigmentation in blue morphs. The function of the sandercyanin remains unclear, but roles in photoprotection and countershading are consistent with available data.

Contact Theory in a Small-Town Settler-Colonial Context

This article builds on group position theory and the subcategorization model of intergroup contact by illustrating how, in a small-town settler-colonial context, contact tends to reproduce, rather than challenge, the inequitable racial structure. In Northwestern Ontario, Indigenous-settler relations are characterized by widespread intergroup marriage and friendship as well as pervasive prejudice and discrimination. Using 18 months of fieldwork and 160 interviews and surveys with First Nations, Métis, and non-Indigenous residents, I show that although contact is associated with less “old-fashioned” prejudice (i.e., overt categorical hostility), it does not necessarily eliminate whites’ superior sense of group position. Even white individuals who have close Indigenous friends or spouses often express laissez-faire racism. Three mutually reinforcing social processes—subtyping, ideology-based homophily, and political avoidance norms—interact to sustain whites’ sense of group superiority and justifications for racial inequity. These processes are facilitated by historical and structural conditions, in this case colonization and small-town dynamics.

Blastomycosis in northwestern Ontario, 2004 to 2014.

Blastomycosis is an invasive fungal disease caused by Blastomyces dermatitidis and the recently discovered Blastomyces gilchristii. The medical charts of 64 patients with confirmed cases of blastomycosis in northwestern Ontario during a 10-year period (2004 to 2014) were retrospectively reviewed. The number of patients diagnosed with blastomycosis in Ontario was observed to have increased substantially compared with before 1990, when blastomycosis was removed from the list of reportable diseases. Aboriginals were observed to be disproportionately represented in the patient population. Of the patients whose smoking status was known, 71.4% had a history of smoking. 59.4% of patients had underlying comorbidities and a higher comorbidity rate was observed among Aboriginal patients. The case-fatality rate from direct complications of blastomycosis disease was calculated to be 20.3%; this case-fatality rate is the highest ever to be reported in Canada and more than double that of previously published Canadian studies. The clinical characteristics of 64 patients diagnosed with blastomycosis are summarized.

Prevalence and Factors Affecting Breastfeeding Among Aboriginal Women in Northwestern Ontario

To evaluate breastfeeding outcomes among Aboriginal women and to determine variables affecting breastfeeding in the early postpartum period. Prospective cohort study. Two sites in Northwestern Ontario, Canada: a tertiary care center and a rural hospital. One hundred thirty breastfeeding Aboriginal women agreed to participate in the study. All women completed a baseline survey in hospital that included questions regarding demographic, prenatal, breastfeeding, obstetric, postpartum, and neonatal characteristics. Women were then telephoned at 4 and 8weeks postpartum to complete additional questionnaires regarding infant feeding. Low rates of breastfeeding initiation (69%) and exclusive breastfeeding were identified at 4 (37.5%) and 8 (35.3%) weeks postpartum. Among those who initiated breastfeeding, duration rates at 4 (86%) and 8weeks (78%) postpartum are comparable to other studies. Variables associated with any and exclusive breastfeeding at 8weeks included the following: (a) household income, (b) intended breastfeeding duration, (c) plan to exclusively breastfeed, (d) perception of meeting their planned duration goal, and (e) higher breastfeeding self-efficacy. Partner support was associated with any breastfeeding at 8weeks but not exclusivity. Women who were breastfeeding exclusively in hospital (prevalence ratio [PR]=.48, 95% confidence interval [CI][0.27, 0.86]), did not smoke (PR=2.5, 95% CI[1.4, 4.3]) and/or use substances during pregnancy (PR=4.5, 95% CI[1.5, 14]) were more likely to be breastfeeding exclusively at 8weeks. Many of the variables may be considered modifiable and amenable to intervention. Targeted interventions should be directed toward improving breastfeeding outcomes among Aboriginal women.

Effect of climatic conditions on height growth of red pine: Results of a provenance test in northwestern Ontario

Response of height growth of red pine (Pinus resinosa Ait.) to changes in climatic conditions was analyzed using data collected in a 48-year-old provenance trial established in northwestern Ontario, Canada. Seed sources for the trial were collected from 23 provenances spanning the natural range of red pine. Mean monthly values of climatic variables were estimated from historical climatic data for 1971 to 2000. Quadratic transfer functions predicting mean tree height at age 48 and tree top height at age 50 were developed using the difference in climatic variables between the seed source provenances and the trial site. The transfer function for mean height at age 48 explained 59% of data variation using the mean minimum temperature in July and sum of precipitation during June to February. For tree top height at age 50, the transfer function explained 55% of data variation using mean minimum temperature in January and sum of precipitation during June to March. The developed equations can be used to select op...

Direct and indirect responses of a freshwater food web to a potent synthetic oestrogen.

Endocrine-disrupting chemicals (EDCs) in municipal effluents directly affect the sexual development and reproductive success of fishes, but indirect effects on invertebrate prey or fish predators through reduced predation or prey availability, respectively, are unknown. At the Experimental Lakes Area in northwestern Ontario, Canada, a long-term, whole-lake experiment was conducted using a before-after-control-impact design to determine both direct and indirect effects of the synthetic oestrogen used in the birth control pill, 17α-ethynyloestradiol (EE2). Algal, microbial, zooplankton and benthic invertebrate communities showed no declines in abundance during three summers of EE2 additions (5-6 ng l(-1)), indicating no direct toxic effects. Recruitment of fathead minnow (Pimephales promelas) failed, leading to a near-extirpation of this species both 2 years during (young-of-year, YOY) and 2 years following (adults and YOY) EE2 additions. Body condition of male lake trout (Salvelinus namaycush) and male and female white sucker (Catostomus commersonii) declined before changes in prey abundance, suggesting direct effects of EE2 on this endpoint. Evidence of indirect effects of EE2 was also observed. Increases in zooplankton, Chaoborus, and emerging insects were observed after 2 or 3 years of EE2 additions, strongly suggesting indirect effects mediated through the reduced abundance of several small-bodied fishes. Biomass of top predator lake trout declined by 23-42% during and after EE2 additions, most probably an indirect effect from the loss of its prey species, the fathead minnow and slimy sculpin (Cottus cognatus). Our results demonstrate that small-scale studies focusing solely on direct effects are likely to underestimate the true environmental impacts of oestrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors.