South-central Ontario Research Articles

Patterns of failure with 18F-DCFPyL PSMA-PET/CT in the post-prostatectomy setting: A regional cohort analysis.

This study aimed to assess the detection rate of prostate cancer recurrence by prostate-specific member antigen positron emission tomography/computed tomography (PSMA PET/CT) with 18F-DCFPyL in patients with residual disease or biochemical recurrence (BCR), and its association with surgical pathology and prostate-specific antigen (PSA) kinetics. Men from South Central Ontario enrolled in the PSMA Registry for Recurrent Prostate cancer (PREP) between April 2019 and December 2021 after radical prostatectomy (RP) and who had 1) pathologic stage N1 or persistent elevated PSA; or 2) BCR (PSA >0.10 ng/mL) where initial postoperative PSA was undetectable were included. A total of 169 men (median age 68 years; interquartile range [IQR] 62-71) with complete data met the above criteria. The median PSA was 0.27 ng/mL (IQR 0.16-0.85) prior to PSMA-PET. Overall positivity rate 59%; when PSA was <0.40 ng/mL, overall positivity rate 42% vs. 85% with PSA ≥0.40 ng/mL (p<0.001). Higher pathologic tumor stage increased detection of regional lymph nodes (LN) (pT2-3a: 32% vs. pT3b: 69%, p<0.001) but not distant metastases (pT2-3a: 12% vs. pT3b: 24%, p=0.15). PSMA-PET detected 18% with prostate bed, 42% with regional LN disease, and 44% with pelvic-only disease. The three most involved LN chains were the internal (21%) and external (20%) iliac, and obturator chains (16%). This prospective study of patients with residual disease or BCR after RP illustrates patterns of failure that could impact diagnosis and postoperative management. Such patients have significant risk of regional LN positivity on PSMA-PET highlighting a need to include pelvic LN within salvage radiotherapy volumes.

IN PRAISE AND SEARCH OF MIDWIFERY WELL-SUITED To RURAL WOMEN

In order to investigate rural maternity care from the perspective of women, narrative interviews were conducted with 36 mothers and 36 health care workers in three small community case study sites in south central Ontario in 2000. Based on the resulting data, this article suggests numerous ways that living rurally affects maternal health. It goes on to explore ways in which midwifery is particularly well-suited to addressing the needs of women living in rural places and identifies sites of resistance to rural midwifery. The research findings indicate that a commitment to the sustained provision of rural midwifery services is well worth the effort and investment required, and this article discusses implications of such a commitment for both practitioners and policy makers.

Diversity and potential sources of introduction of the beech leaf nematode (Litylenchus crenatae mccannii) to Ontario, Canada

Litylenchus crenatae mccannii is a foliar nematode that causes severe damage to beech, known as beech leaf disease (BLD). Previous studies have characterized and identified L. crenataein Japan and a subspecies L. crenatae mccannii in the USA. Litylenchus crenatae mccannii has been found to cause BLD in native and non-native beech hosts in North America. As little is known about the distribution and diversity of the nematode in Ontario, Canada, beech foliage was sampled throughout southcentral Ontario. Incidence and severity maps show that BLD spread from its first detections in 2017, in Elgin and Norfolk counties, to the west and northeast. A gradient in severity and incidence was observed with the highest ratings at the locations where it was originally found. The extent of the nematode’s distribution is much broader than BLD, occurring throughout much of the range of American beech. Sequences of two barcoding loci for the L. crenatae mccannii isolates from 11 locations in Ontario showed 100% similarity within and among these locations. The genotype of L. crenatae mccannii found in Ontario is the same as that identified in the USA. This finding is consistent with the fact that 92% of beech imported into Canada is from the USA and suggests that the USA could be the origin of L. crenatae mccannii nematodes in Ontario or that both countries have imported beech trees from the same source country of BLD. This research provides motivation for further studies to clarify the sources of L. crenatae mccannii.

A SUMMARY OF RADIOCARBON MEASUREMENTS OF FLUVIAL AND COLLUVIAL DEPOSITS IN CATCHMENTS OF SOUTH-CENTRAL ONTARIO, CANADA

ABSTRACTFluvial and colluvial deposits of Late Holocene age in South-Central Ontario catchments have provided few 14C dates, most by conventional methods registering century-old ages. Other young deposits, dated by conventional and accelerator mass spectrometry radiocarbon (AMS 14C), have yielded bomb-affected post-1950 ages over variable time limits. Attempts to date the base of Ah and lower-in-section soil horizons, in Early to Late Holocene stream terrace deposits, have yielded atomic bomb effects. Comparing bomb contamination in Late Holocene fluvial deposits, using both conventional and AMS methods, identifies a mix of bomb-affected beds juxtaposed with dated beds, the latter yielding ages with narrow standard deviations. Colluvial deposits overlying key glacial sections in the Rouge Catchment, while rare, yield bracketed AMS ages for an Ahbk horizon that refines weathering times relative to previously obtained conventional 14C dates. Bomb-affected sediment appears variably distributed within floodplain soils and in the ground soil of a colluvial section. Mass wasted deposits, with AMS 14C ages spread over the last few centuries, appear related to Little Ice Age (LIA) changes in climate, corroborated by pollen records. Further, these AMS-14C dated beds calibrate weathering of secondary Fe-Al oxihydroxides over the first half a millennium of weathering time.

Dynamics of dissolved organic carbon during drought and flood events: A phase-by-stages perspective

Dissolved organic carbon (DOC) is a key water quality parameter that plays a crucial role in controlling aquatic ecosystems and carbon cycling. Understanding DOC dynamics during hydrological extremes (i.e., droughts and floods) helps in managing water quality, but such variability is rarely studied. Furthermore, how differences in DOC concentrations among phase-by-stages of drought/flood affect simulation performances based on hydrological features remains unclear. Here, phase-by-stages of hydrological drought (flood) were divided into intensification (rising) and recovery (falling) periods based on drought peak intensity (flood peak intensity). The long-term (1976–2019) daily discharge and weekly (biweekly) DOC concentrations from four headwater streams with different watershed sizes (from 9.97 to 119.09 ha) in south-central Ontario, Canada, were used to achieve the above aims. The results showed that (i) the average DOC concentration during intensification (rising) stage of drought (flood) was smaller (larger) than during recovery (falling). (ii) Simulations performed better when accounting for phase-by-stages of drought/flood, with reductions in mean absolute percentage error of 32.85 % and 53.59 % for drought and flood events, respectively. These results will help understand the dynamics of DOC during hydrological extremes and improve simulation performance of numerical models for water quality parameters under changing environmental conditions.

Community science to the rescue: capturing water quality data during the COVID-19 pandemic

In 2020, the COVID-19 pandemic interrupted all aspects of human activity, including environmental research and monitoring. Despite a lack of laboratory access and other restrictive measures, we adapted an existing community science monitoring program to continue through the summer of 2020. We worked with local community groups to recruit 58 volunteers who collected lake water samples from 60 sites on 16 lakes in south-central Ontario from June to September 2020. We organized drop-off depots and had volunteers freeze samples to monitor nearshore nutrients (phosphorus and nitrogen) and chlorophyll-a. A survey was distributed to volunteers to analyze lake-front property owners’ activities during the pandemic. We found spatial patterns in nearshore water quality across the lakes, with sub-watershed development being a significant predictor of nutrients and chlorophyll-a. Additionally, pre-pandemic (2019) and pandemic (2020 and 2021) nutrient concentrations were compared, but there was no clear impact of the pandemic on nearshore nutrient concentrations, despite changes in lake-front property owners activities. Overall, this study demonstrated the ability of community science to provide water quality data on a large spatial scale despite a major societal disruption, providing insight into regional nutrient trends during the first year of the pandemic.

89. On-going impact of the SARS-CoV-2 pandemic on the evolution of carbapenemase-producing Enterobacterales in Ontario, Canada

Abstract Background The spread of carbapenemase-producing Enterobacterales (CPE) is global threat. Numerous outbreaks of CPE have been reported during the COVID-19 pandemic. We describe the impact of of the SARS-CoV-2 pandemic on the emergence of CPE in south-central Ontario, Canada. Incidence of clinical isolates of CPE and isolates with different CPE genes in Toronto/Peel region, 2017–2021. The upper panel shows the incidence of patients with clinical isolates of CPE by year and quarter from q4 2007 to q1 2022. The lower panel shows the incidence of patients with clinical isolates with different carbapenemase genes by fiscal year during the same period. Methods TIBDN has performed population-based surveillance for CPE in Toronto/Peel region (pop 4.5M) from first identified isolate in 2007. All laboratories test/refer all carbapenem non-susceptible Enterobacterial isolates for identification of CPE. Hospital charts are reviewed and patients/physicians interviewed. Population data are obtained from Statistics Canada. Results From 10/2007 to 3/31/2022, 1367 persons colonized or infected with CPE were identified. Their median age was 68.7yrs (IQR 54–78yrs); 761 (56%) were male. 772 (56%) were colonized when first identified; 115 (8.4%) were bacteremic at identification or subsequently developed bacteremia. The most common organisms were E. coli (651, 48%), K. pneumoniae (436, 32%), Enterobacter spp. (146, 11%), Citrobacter spp (62, 5%); the most common genes were NDM±OXA-48 (722, 53%), OXA-48-like (341, 25%), KPC (225, 16%), VIM (44, 3%). The incidence of CPE infections increased steadily until 3/2020 then declined by 61% and remained stable until 3/2022 (Figure, upper panel). The decline was greater for E. coli (56% decrease), K. pneumoniae (62%) than for Enterobacter spp. (30%) and other species (19%). It occurred in all genes in 2020; however, KPC containing organisms increased again in 2021 (Figure, lower panel). Conclusion The advent of the COVID-19 pandemic was associated with an immediate, substantial decline in the incidence of patients with CPE in our population area. This decline occurred in both isolates with genes usually occurring in cases imported from other countries, and in those usually occurring in cases associated with transmission within Canadian hospitals. Decreased travel and enhanced infection prevention and control in hospitals may both have contributed to reductions in CPE during the pandemic. Disclosures All Authors: No reported disclosures.

Simulating dissolved organic carbon during dryness/wetness periods based on hydrological characteristics under multiple timescales

Understanding and simulating dissolved organic carbon (DOC) concentrations is a challenge with important implications for water quality projections and carbon balance estimates, particularly at the event-scale. Hydrological dryness/wetness represents water shortage/surplus in surface water. Previous studies have analyzed the dynamic patterns of DOC concentrations during either dryness or wetness (or rewetting) periods. However, the dynamic patterns of DOC concentrations and corresponding simulations during both dryness and wetness events, based on their characteristics (i.e., duration and severity), remain to be fully understood, particularly under multiple timescales. This study proposed a framework to help overcome this limitation. The standardized streamflow index (SSI) combined with run theory was used to describe the dryness/wetness characteristics at the monthly, seasonal, and annual scales. Simulation models were constructed and validated based on the multivariable linear regression model and cross-validation method. Three evaluation indicators, namely, the coefficient of determination (R2), Nash-Sutcliffe efficiency (NSE), and mean absolute percentage error (MAPE, %), were employed to determine the optimal model. This model was then applied to additional basins based on the correction coefficient method. Three nearby basins (HP3a, HP4, and HP6), with different catchment areas (9.28 to 122.80 ha) and long-term (41 years) daily streamflow and weekly (or biweekly) DOC measurements in the Harp Lake catchment, south-central Ontario, Canada, were used to demonstrate the usefulness of the framework. Data from HP3a was used to construct and validate the simulation model, and the model was applied to the HP4 and HP6 basins. Results show that the average DOC concentration during the dryness events is lower than that in the wetness events at the monthly, seasonal, and annual scales. The average, maximum, and minimum DOC concentrations during the dryness events increased with the dryness/wetness index timescales, but decreased during the wetness events. The optimal model was able to accurately simulate the DOC concentrations (R2 ≥ 0.90, NSE ≥ 0.90, and MAPE ≤ 10 %) at the monthly, seasonal, and annual scales based on the hydrological characteristics during the dryness and wetness periods, respectively, and the application results exhibit a good performance. The proposed framework can help improve the forecasting of DOC concentrations and the corresponding ecological coping strategies at the event-scale under changing environments.

First Report of Botryosphaeria dothidea Causing Stem Canker and Dieback of Apple Trees in Ontario, Canada.

Apple trees (Malus domestica L. Borkh.) exhibiting extensive and unknown tree fruit decline symptoms were observed in commercial orchards over the past 5 years in Ontario, Canada. The trees exhibited shoot dieback, attached wilted leaves and cankers on the main trunk. Trees with rapid development of cankers upward from the graft union developed extensive vascular discoloration that resulted in sudden collapse of the entire tree. In 2018-19, up to 42% mortality was observed on 2- to 8-year old apple trees. Nine symptomatic trees were collected from two orchards located in southwestern and one in southcentral Ontario. Samples (1 cm length) were collected from symptomatic trunk and shoot tissue, surface sterilized with 70% ethanol for 30 sec, followed by 1% NaClO for 20 min and three rinses in sterile water. The samples were air-dried and placed on a 2% potato dextrose agar (PDA, Difco) culture media supplemented with kanamycin (50 mg L-1). The PDA plates were incubated at 22°C for 5 days in the dark. All fungal colony-forming units that developed were hyphal-tip transferred to individual PDA plates and incubated at 22°C for 7 days in the dark. Purified mycelial isolates were classified into morphotypes prior to molecular identification. One morphotype showed white to olive-green colonies that developed on a moderately dense mycelial mat with aerial hyphae. Several solitary and globose black pycnidia that contained a single ostiole were produced on pine needles on PDA after incubation at 22°C for 14 days in the dark. Conidia were hyaline, fusiform, aseptate with an average size of 3.9 - 5.2 x 21.4 - 26.6 μm (N=50). Genomic DNA was extracted from 5-day old culture of a representative isolate, #M68-17, grown on PDA using the Plant/Fungi DNA Isolation Kit (Norgen Biotech Corp., Thorold, ON, Canada). The rDNA internal transcribed spacer (ITS), translation elongation factor 1- alpha gene (TEF-1α), and β-tubulin gene (TUB2) were amplified using the primer pairs ITS1/ITS4 (White et al. 1990), EF1-728F/EF1-986R (Carbone and Kohn 1999), and Bt2a/Bt2b (O'Donnell et al. 1998), respectively, and sequenced. The nucleotide sequences obtained (GenBank # MZ926850, MZ934654, MZ934655) were 100.00% similar to those of Botyrosphaeria dothidea (Moug. ex Fr.) Ces. & De Not. isolates from other hosts in several countries in the NCBI database (MT111097, MT309401, MN515421, respectively). Randomized Accelerated Maximum Likelihood (RAxML) analysis using the three gene sequence data was completed (Stamatakis et al. 2008). The isolate #M68-17 was clustered with high bootstrap support values with the B. dothidea isolates from the fungal biodiversity centre (CBS) collection, including the ex-epitype (CBS 115476, CBS 110302) (Fig. 1). A living culture of the representative isolate, #M68-17, was deposited in the Canadian Collection of Fungal Cultures (DAOMC 252246). Pathogenicity tests were conducted in the lab on wood cuttings and in planta. Ten 20 cm apple cuttings and five potted one year old apple seedlings were surface sterilized, wounded and inoculated with 4 mm mycelium agar plug from a 5-day old culture of isolate #M68-17 and wrapped with Parafilm. Three control apple cuttings and seedlings were inoculated with PDA plugs and incubated in the same environment. Cuttings were placed inside a clear plastic container with moist paper towels and incubated at room temperature in the dark. Seedlings were placed in an open-air area between two greenhouses and watered as needed. Twelve days post-inoculation, the average length of the developed necrotic lesions on cuttings was 8.8 ± 0.4 cm. Necrotic and sunken canker symptoms appeared at 10 days, spread upward from the inoculation point and by 6 weeks the upper portion of the seedling was dead (Fig. 2). B. dothidea was isolated from all the inoculated cuttings and seedlings, thus fulfilling Koch's postulates. Control cuttings and seedlings showed no symptoms, and the fungus was not isolated from the wood. B. dothidea was reported as a pathogen causing cankers on a wide range of woody crop plants including apples, almonds, pistachios, hazelnut, walnut, olive and grapes in the United States, China, Uruguay, Spain, Tunisia and Turkey (Chebil et al. 2014; Delgado-Cerrone et al. 2016; Moral et al. 2019; Tang et al. 2012; Türkölmez et al. 2016). However, this is the first report of B. dothidea causing stem canker and death of young apple seedlings in Ontario, Canada. The findings suggest that B. dothidea has the potential to severely affect apple production in Ontario. Accurate identification of pathogen(s) associated with apple decline will support management of the disease.

Atmospheric deposition of anthropogenic particles and microplastics in south-central Ontario, Canada

Microplastics are ubiquitous in the environment; however, few studies have examined their abundance in atmospheric deposition in pristine environments, remote from anthropogenic emission sources. In the current study, atmospheric deposition samples were collected for 13 months (February 2019–March 2020) from four precipitation chemistry monitoring stations located in Muskoka-Haliburton, south-central Ontario, Canada. Anthropogenic particles (i.e., synthetic particles but not necessarily plastic) were observed at each station with an average deposition rate of 57 particles/m2/day (range from 32 to 73 particles/m2/day). Of the anthropogenic particles identified, 12% were plastic resulting in an average microplastic (mp) deposition rate of 7 mp/m2/day (range 4–9 mp/m2/day). Approximately 85% of the particles were fibres with fragments comprising only 15%. The most common particle colours were blue and red with 50% of the fragments and 84% of fibres being one of these two colours. Raman spectroscopy determined that polyamide and polyethylene terephthalate were the two most abundant polymers at 24% and 19%, respectively. Across the four stations anthropogenic particle concentrations were significantly related to wind speed (rs = 0.32 to 0.62) and temperature (rs = −0.53 to −0.84), with a noticeable increase in particle concentration when wind shifted from the west (average of 7.2 mp/L) to the south-east (average of 11.5 mp/L). Faster wind speed resulted in a larger airshed source area, and the seasonal effect associated with changes in temperature and wind direction led to changes in potential source regions that were contributing microplastics, such as the Greater Toronto Area (>200 km away).

Using diatoms to track road-salt seepage into small, shallow, softwater Ontario lakes

Since the 1950s, the widespread application of road salt for winter road maintenance and safety in cold regions has led to increased conductivity levels in many freshwater systems. Salting practices have adversely affected freshwater biota; however, the magnitude of ecological impacts may vary by species and ecosystem. Here, we examine diatom assemblage changes during the past ∼200 years from the sedimentary records of five impacted lakes (measured specific conductance values of 149–350 µS·cm−1) and a reference lake (18 µS·cm−1) located in the Muskoka River Watershed, south-central Ontario, Canada. Diatom compositional changes in the road-salt-impacted sites were consistent with increasing conductivity and increased diatom-inferred (DI)-conductivity was evident during the latter half of the 20th century in the impacted lakes, concurrent with known road-salt application. The strongest predictor of DI-conductivity changes among the six lakes was the kilometre equivalents of roads within the watershed (i.e., kilometres of road × number of lanes). Similar to changes observed in a previous study focusing on cladoceran assemblages, we conclude that even modest applications of road salt can affect diatom assemblages in softwater lakes.

Dissolved organic carbon response to hydrological drought characteristics: Based on long-term measurements of headwater streams

Influence of extreme hydrological events on water quality has been widely concerned. For instance, droughts can inhibit dissolved organic carbon (DOC) exports or imports. However, the response relationship of DOC to hydrological drought characteristics (i.e., duration and severity) requires more in-depth research. We propose an integrated framework for constructing, validating, and applying the response relationship model, and investigate the capability of response model to simulate DOC based on hydrological drought characteristics. Three headwater basins (HP3a, HP4, and HP6), with different drainage areas (9.28–122.80 ha) and long-term (>40 year) observed DOC concentration and hydrometeorological data, in Harp Lake catchment, south-central Ontario, southeastern Canada, are used to demonstrate the proposed framework. Run theory and variable drought thresholds (VDTs) are used to identify hydrological drought characteristics, and DOC during hydrological drought is extracted. Based on the extracted hydrological drought characteristics and DOC for one basin (i.e., HP3a), the response relationship model is constructed and validated, and then applied to other two basins (i.e., HP4 and HP6). Three evaluation indicators: coefficient of determination (R2), root-mean-square-error (RMSE), and mean absolute percentage error (MAPE), are served to test the goodness-of-fit performance of the response relationship model. The results show that (i) annual DOC concentration showed a significant (a = 0.01) increasing trend during 1978–2018 in the study basin. (ii) During the hydrological drought, the variation of temperature affected DOC variation indirectly through direct influence on SO4 variation. (iii) The response sensitivity of DOC to hydrologic process with different timescales is varying within a year, namely, there is a larger response sensitivity from March to May than in other months. (iv) DOC during the hydrological drought has a close and regular linear relationship with hydrological drought characteristics, i.e., with the increase of drought duration and severity, DOC concentration also increases. The relationship with drought duration is better than that of severity (R2 = 0.92 vs 0.35). (v) The response relationship model (autoregressive integrated moving average) can simulate DOC in hydrological drought (R2 ≥ 0.87, RMSE ≤ 0.86, MAPE ≤ 13.69%) at HP3a, and also has good applications at HP4 and HP6 basins. These results provide an improved understanding of DOC-drought relationship, and may support policy makers that look for increased resilience of aquatic ecological security to droughts.

Community structure, species–habitat relationships, and conservation of amphibians in forested vernal pools in the Georgian Bay region of Ontario

Forested vernal pools serve an integral role in the recruitment of amphibians in glaciated northeastern North America. In south-central Ontario, vernal pools exist in relatively unimpacted forest networks, but the amphibian communities face uncertain challenges from anthropogenic-induced climate change. We surveyed amphibian larvae and collected measurements of habitat characteristics from vernal pools to collect baseline information on amphibian community structure and species–habitat relationships. Amphibian communities were influenced by hydroperiod length and canopy openness, and the relative abundances of early breeding amphibians were affected by changes in the structure of vegetation communities within pools. Our study suggests that, even across moderate ranges of breeding habitat characteristics, the structure of amphibian communities is dynamic. With anthropogenic-induced climate change leading to more drought-prone summers, the conservation of intact forests that support diverse wetland assemblages will be a necessary component of future legislation.

Atmospheric Deposition of Anthropogenic Particles and Microplastics in South-Central Ontario, Canada

Atmospheric Deposition of Anthropogenic Particles and Microplastics in South-Central Ontario, Canada

411. Significance of a Known Epidemiological Link to a COVID-19 Index Case and Severity of COVID-19 Infection

Abstract Background Several factors have been associated with severity of COVID-19 disease, but there remains a paucity of data surrounding whether the nature of exposure is impactful. Evidence demonstrating the correlation between initial viral exposure dose and disease severity exists for many viral infections. Observational studies have suggested that the exposure context, which can be considered a proxy for magnitude of viral inoculum, may influence severity of COVID-19 infection. We aimed to assess whether having a known exposure, as a proxy for higher inoculum dose to COVID-19, was associated with more severe outcomes for individuals hospitalized with COVID-19. Methods We created a retrospective cohort of community-dwelling adults hospitalized for COVID-19 in south-central Ontario from April 1, 2020 - January 14, 2021. Individuals or next of kin were contacted to ascertain exposure history. The primary outcome was death, intensive care unit (ICU) admission, or mechanical ventilation (MV) within 30 days of admission. A multivariable logistic regression model was used to determine whether a known exposure was associated with worse outcomes. Results 1097 individuals with community acquired COVID-19 required hospitalization; of these, 942 (86%) had available exposure data. In this group, the median age was 65, 44% were women, 84% lived in a private residence, 59% had a frailty score (FS) of 1 – 3 while 40% had a FS of 4 – 9, and 28% had a known exposure. Overall, the primary outcome occurred in 368/942 (39%) patients. Having a known exposure was not associated with worse outcome (OR 1.14, 95% CI 0.84–1.54, p = 0.41). Male gender (OR 1.41, 95% CI 1.06–1.89; p = 0.018), age (OR 1.01/year, 95% CI 1.00–1.03, p = 0.03), frailty (OR 1.22/point, 95% CI 1.09–1.36, p = 0.001) and living with at least one other person (OR 1.57, 95% CI 1.09–2.28, p = 0.017) were all associated with death, ICU admission, or MV within 30 days of admission. Conclusion While having a known exposure to a person with COVID-19 was not associated with worse outcome, the identified increased severity of illness associated with cohabitation suggests context of exposure may have a role in disease severity. This data and future studies can be used to guide public health recommendations to not only minimize transmission, but severity of COVID-19 infection. Disclosures All Authors: No reported disclosures

1309. Incidence and Epidemiology of Invasive Pneumococcal Disease due to Serotype 3 in South-Central Ontario

BackgroundIn our population, the most common serotype (ST) of S. pneumoniae causing invasive pneumococcal disease (IPD) is now ST 3. We undertook an analysis of population based surveillance for IPD to examine the incidence and epidemiology of ST 3 disease over the last 25 years.MethodsThe Toronto Invasive Bacterial Diseases Network has performed population-based surveillance for IPD in Toronto/Peel region (pop’n 4.5M) since 1995. All sterile site isolates of S. pneumoniae are reported to a central study laboratory, isolates are serotyped, and clinical and vaccination data are collected via patient and physician interview and chart review. Population data are obtained from Statistics Canada.ResultsFrom 1995-2020, 11032 episodes of IPD occurred; 10015 had STs available, and 10484 clinical data. Overall, ST 3 comprised 9.2% of cases (N=931). Compared to other patients with IPD, those with ST 3 IPD were older (median age 65 vs. 58.5, P< .001), more likely to have underlying lung (22.7% v 16.0%, P< .0001) and cardiac (21.7 v 18.4, P=.02) disease and less likely to be immunocompromised (IC) (23.1% v 29.0% P< .0001). ST3 episodes were more likely to be pneumonia (81% v 65%), less likely to be bacteremia without focus (7.6% v 18.9%), and more likely to require ICU admission (42.3% v 25.1%) and to die (27.1% v 16.6%). In multivariable analysis, patients with ST 3 disease remained more likely to die (OR 1.65; 95%CI1.3-2.0). Over time, the proportion of patients with ST 3 IPD who were nursing home (NH) residents (18/171 in 1995-2000 vs. 4/215 in 2016-2020, P=.0002), and who were IC (46/169 in 1995-2000 vs 39/204 in 2016-2020, P=.007) decreased significantly; in IPD due to other STs, the proportion who were NH residents declined, but the proportion IC increased significantly. The case fatality rate (CFR) declined significantly in IPD due to ST3 but not other STs (Figure 1). Changes in incidence are shown in Figure 2.Figure 2: Incidence of serotype 3 IPD over time, Toronto/Peel, 1995-2020 The incidence of ST3 IPD in children and adults under 65 did not change significantly from 1995/96 to 2019/20. In older adults, the annual incidence of disease declined from 4.98 per 100,000 per year in 1995-2000 to 3.53 per 100,000 per year in 2001-2010 (IRR 0.71, 95%CI 0.56-0.90), then to 2.23 per 100,000 per year in 2011-2020 (IRR compared to 2001-2010 0.63, 95%CI 0.50-0.79)FIgure 2: Case fatality rate of IPD due to serotype 3 and other serotypes over time, 1995-2020, Toronto-Peel The case fatality rate of IPD due to ST3 declined from 37.6% (56/149) in 1995-2000 to 50/235 (21.3%) in 2015-2020 (P<.0001). The CFR in other serotypes did not change.ConclusionThe epidemiology of IPD due to ST3 has changed significantly over time and the CFR has declined. The incidence of ST3 disease in children and younger adults has not changed significantly, although the power to detect change is low in children. In older adults the incidence of ST3 disease declined significantly after PPV23 introduction in 1995/6 and again after PCV13 introduction for children.Disclosures All Authors: No reported disclosures

Use of Sentinel-2 Data to Improve Multivariate Tree Species Composition in a Forest Resource Inventory

Aerial-photo interpreted inventories of forest resources, including tree species composition, are valuable in forest resource management, but are expensive to create and can be relatively inaccurate. Because of differences among tree species in their spectral properties and seasonal phenologies, it might be possible to improve such forest resource inventory information (FRI) by using it in concert with multispectral satellite information from multiple time periods. We used Sentinel-2 information from nine spectral bands and 12 dates within a two-year period to model multivariate percent tree species composition in &gt;51,000 forest stands in the FRI of south-central Ontario, Canada. Accuracy of random forest (RF) and convolutional neural network (CNN) predictions were tested using species-specific basal area information from 155 0.25-ha field plots. Additionally, we created models using the Sentinel-2 information in concert with the field data and compared the accuracy of these models and the FRI-based models by use of basal areas from a second (13.7-ha) field data set. Based on average R2 values across species in the two field data sets, the Sentinel-FRI models outperformed the FRI, showing 1.5- and 1.7-fold improvements relative to the FRI for RF and 2.1- and 2.2-fold improvements for CNN (mean R2: 0.141–0.169 (FRI); 0.217–0.295 (RF); 0.307–0.352 (CNN)). Models created with the field data performed even better: improvements relative to the FRI were 2.1-fold for RF and 2.8-fold for CNN (mean R2: 0.169 (FRI); 0.356 (RF); 0.469 (CNN)). As predicted, R2 values between FRI- and field-trained predictions were higher than R2 values with the FRI. Of the 21 tree species evaluated, 8 relatively rare species had poor models in all cases. Our multivariate approach allowed us to use more FRI stands in model creation than if we had been restricted to stands dominated by single species and allowed us to map species abundances at higher resolution. It might be possible to improve models further by use of tree stem maps and incorporation of the effects of canopy disturbances.

Eastern Wood-Pewee (Contopus virens) reproductive success in red pine plantations and deciduous forests in Ontario, Canada

Pine plantations comprise about 7% of total world forest cover and are increasing across the globe. We compared settlement times, breeding densities, and the effects of time, habitat, and nest-site characteristics on the nest success of Eastern Wood-Pewees (Contopus virens) in red pine (Pinus resinosa) plantations and deciduous forest stands in south-central Ontario, Canada, in 2007 and 2008. Our goal was to evaluate the quality of these 2 habitats for this declining aerial insectivore. Pine plantations and deciduous forest stands were settled nearly simultaneously and at similar breeding densities, suggesting no preference for either habitat. Nest success in pine plantations (22%) was lower than in deciduous forests (35%), corresponding to higher counts of red squirrels (Tamiasciurus hudsonicus) and Blue Jays (Cyanocitta cristata) in plantations. Daily nest survival was lowest when nestlings were about 5 d old, but improved substantially as nestlings aged, and over the nesting season. In both habitats, increased nest visibility was correlated with decreased nest survival. In pine plantations, nest survival was higher where trees were more dispersed, while in deciduous forests, nests situated farther from tree trunks had higher survival rates. In both habitats, Eastern Wood-Pewees may use outward branches, when available, to detect movement and then evade potential nest predators. Although pine plantations provide breeding habitat for Eastern Wood-Pewees, management that increases hardwood understories and overstories may help to reduce visibility of Eastern Wood-Pewee nests and to reduce the populations of generalist songbird predators.

Spatial population genetics reveals competitive imbalances threatening local apex predator persistence

The eastern wolf (Canis lycaon), a species of conservation concern in Canada, is currently restricted to small fragmented populations in south-central Ontario and hybridizes with both encroaching gray wolves and coyote-like canids. We examined niche dynamics in canids undergoing hybridization to determine whether competition among individuals with coyote (Canis latrans) or gray wolf (Canis lupus) ancestry, or their related hybrids, could threaten persistence of the eastern wolf in south-central Canada. Our integrative approach combined extensive genotyping and comparative niche analyses across the hybrid zone to assess available and utilized niche space across all three parental species and their hybrids within the zone of admixture. We focused on detecting niche imbalances within the canid clade that indicate competitive threats, and used these data to identify specific geographic regions that disproportionately favor eastern wolves and might confer natural exclusion of competing canids. We detected low genetic and ecological differentiation among groups across the region. Niche dynamics in the admixture zone were dominated by gray wolf and coyote-like canids, with coyote-like canids in particular exhibiting niche space that overlapped entirely with eastern wolves. Conservation action for eastern wolves must either exploit the narrow niche space that differentiates them from other canids, representing ~5% of their currently occupied space, or accept whichever group dominates the landscapes regardless of genetic makeup. This study suggests that competitive disadvantage can limit species' recovery efforts, and thereby potentially warrant management that targets factors promoting ecological differentiation between groups.

The Archaeology of Inundated Cultural Landscapes in Freshwater Lake Systems: Preliminary Insights from a Multi-Methods Study in the Kawartha Lakes Region, Ontario

In this paper, we review the goals, methods, and results of our modelling of the shoreline history and archaeological survey of the inundated portions of a freshwater lake system within the Lake Ontario watershed of south-central Ontario, Canada. We first review the character of the regional archaeological record and highlight the likelihood that the relatively few documented sites in this region before 6000 cal BP is due to landscape inundation from shoreline transgression. The first part of our analytical work focuses on the derivation of paleoshoreline models to identified now flooded, but formerly inhabitable landscapes. The second phase of our work reports on the shallow water survey of high potential areas. We documented over 1000 artifacts in a set of targeted surveys, including the presence of material diagnostic of the early Holocene, which is underrepresented in the terrestrial record. The results of our work emphasize the importance of evaluating the potential for cultural landscape inundation in freshwater lake systems and, when so identified, how underwater surveys contribute to regional studies of hunter-gatherer settlement and land use patterns.