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1
Lean, D. R. S., and R. Knowles. "Nitrogen Transformations in Lake Ontario." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 12 (December 1, 1987): 2133–43. http://dx.doi.org/10.1139/f87-262.
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Concentrations of ammonium plus nitrite in Lake Ontario were highly correlated with ammonium regeneration from zooplankton excretion (r = 0.966), inferring that elevated nitrite concentrations result from nitrification. Nitrapyrin-sensitive dark 14C-labeled bicarbonate assays confirmed high rates of nitrification by chemoautotrophic bacteria. 15N-labeled nitrate experiments showed that nitrate, not ammonium, was the principal form of N used for total microbial protein synthesis. Size fractionation experiments also suggested that small cells were responsible for most of the ammonium uptake, while large cells used mostly nitrate. Nitrate depletion in the surface waters during summer stratification resulted from movement to particulate N, nitrite, and ammonium as well as losses in particulate N due to sedimentation. At least one third, however, was unaccounted for (i.e. 30 mg N∙m−2∙d−1) and may have been converted to protein which would move up the food chain to larger organisms (e.g. fish) not sampled during conventional water chemistry. Nitrous oxide profiles showed that nitrate losses through denitrification are unlikely to occur. Consequently, unless nitrate loading to Lake Ontario is reduced, nitrate concentrations should be expected to continue to increase.
2
Symons, D. T. A. "Paleomagnetism of the Keweenawan Chipman Lake and Seabrook Lake carbonatite complexes, Ontario." Canadian Journal of Earth Sciences 29, no. 6 (June 1, 1992): 1215–23. http://dx.doi.org/10.1139/e92-097.
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The Chipman Lake complex crops out as a series of carbonatite and related alkalic mafic dikes in the Wabigoon Subprovince of the Superior Province, whereas the Seabrook Lake complex crops out as an alkalic syenite – carbonatite stock in the Abitibi Subprovince. Paleomagnetic analysis was done on specimens from 23 and 19 sites located in and around the Chipman Lake and Seabrook Lake complexes, respectively, using detailed alternating-field and thermal step demagnetization and isothermal remanent magnetization tests. Contact tests with adjacent Archean host rocks show that both complexes retain a primary characteristic remanence (ChRM). The Chipman Lake's ChRM is retained in 11 dikes with normal polarity and one dike with reversed polarity and at one site with normal polarity and one site with reversed polarity from the fenite alteration zone. Its ChRM gives a pole position at 186°E, 38°N (dp = 7°, dm = 11°), which corresponds to a Keweenawan age of 1098 ± 10 Ma, suggesting that younger K–Ar amphibole ages do not date emplacement. The ChRM of the host rock, the Chipman Lake diorite stock, gives a pole at 49°E, 51°N (dp = 8°, dm = 13°), showing that it is not part of the Keweenawan complex but may be a 2.45 Ga Matachewan intrusive. The Seabrook Lake complex's ChRM is found at six normal polarity sites from within the complex and at four normal and three reversed polarity sites from within the fenitized Archean granite and Matachewan diabase of the contact aureole. It gives a pole position at 180°E, 46°N (dp = 11°, dm = 17°), which corresponds to a Keweenawan age of 1103 ± 10 Ma, agreeing with K/Ar biotite ages. The paleomagnetic data indicate that no significant motion on the Kapuskasing Structural Zone occurred after emplacement of the complexes excluding minor vertical uplift of less than about 4 km, and that there were multiple polarity transitions of a symmetric Earth's magnetic field during Keweenawan time.
3
Harrow-Lyle, Tyler, and Andrea E. Kirkwood. "The invasive macrophyte Nitellopsis obtusa may facilitate the invasive mussel Dreissena polymorpha and Microcystis blooms in a large, shallow lake." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 7 (July 2020): 1201–8. http://dx.doi.org/10.1139/cjfas-2019-0337.
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This study was conducted in Lake Scugog, a large, shallow reservoir in Ontario, Canada. Historically, Lake Scugog has been a macrophyte-dominated ecosystem with a productive fishery. In recent years, periodic Microcystis blooms have erupted coinciding with the discovery of the non-native macroalga Nitellopsis obtusa in the lake. From 2016 to 2018, we conducted field surveys to assess the physical, chemical, and biological conditions across 12 sites spanning the lake. All study species (N. obtusa, Dreissena polymorpha, and Microcystis spp.) increased from 2016 to 2018. To determine potential biotic and abiotic drivers of Microcystis blooms, we used a structural equation modelling (SEM) approach. The SEM (r2 = 0.27, p < 0.05) revealed several positive (precipitation, chloride, depth, and N. obtusa) and negative (total nitrogen) explanatory variables for Microcystis biomass. The only statistically significant biotic driver was N. obtusa, which was a positive explanatory variable for both D. polymorpha and Microcystis. Future work will test the efficacy of the SEM model across Ontario lakes to confirm the facilitative role of N. obtusa on D. polymorpha and Microcystis populations.
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Wiegand, M. D., T. A. Johnston, W. C. Leggett, K. E. Watchorn, A. J. Ballevona, L. R. Porteous, and J. M. Casselman. "Contrasting strategies of ova lipid provisioning in relation to maternal characteristics in three walleye (Sander vitreus) populations." Canadian Journal of Fisheries and Aquatic Sciences 64, no. 4 (April 1, 2007): 700–712. http://dx.doi.org/10.1139/f07-033.
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We examined how the lipid content and fatty acid composition of walleye (Sander vitreus) ova varied with respect to maternal characteristics, particularly indices of body nutrient reserves, within three spawning populations that varied in maternal age, size, and somatic lipid reserves. We also compared the variability in ova lipid composition among three populations with that observed among spawning years within one of these populations. Maternal characteristics had little influence on ova lipid content. In Lake Ontario, percentages of docosahexaenoic acid (22:6(n-3), DHA) and arachidonic acid (20:4(n-6), AA) increased with maternal length, while those of eicosapentaenoic acid (20:5(n-3), EPA) declined. In Lake Nipissing, maternal age had similar effects on AA and EPA, but not DHA. The Lake Winnipeg population did not conform to the trends of the other two populations, and ova from this population had very low levels of AA. We hypothesize that there are similar selection pressures on the Lake Ontario and Lake Nipissing populations with respect to desirable ova fatty acid profiles. Lake Winnipeg walleye may experience different selection pressures or may be unable to conform to the trends observed in the other two lakes.
5
Grewe, Peter M., Charles C. Krueger, Charles F. Aquadro, Eldredge Bermingham, Harold L. Kincaid, and Bernie May. "Mitochondrial DNA Variation among Lake Trout (Salvelinus namaycush) Strains Stocked into Lake Ontario." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 11 (November 1, 1993): 2397–403. http://dx.doi.org/10.1139/f93-264.
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Mitochondrial DNA (mtDNA) variation was examined in 492 fish representing six lake trout (Salvelinus namaycush) strains used for stocking and restoring populations in Lake Ontario. mtDNA was extracted from 432 fish by a total DNA isolation protocol (CTAB). mtDNA was also extracted from 60 additional fish using the purification method of CsCl ultracentrifugation. The more rapid CTAB protocol made feasible analysis of sample sizes (n ≥ 80 per strain) required as baseline data for future mixed-stock analysis (MSA). Restriction enzymes AvaI, BamHI, HinfI, and TaqI resolved seven mtDNA haplotypes and were used to characterize fish from each of six strains (Clearwater, Jenny, Killala, Manitou, Seneca, and Superior). Frequencies of these haplotypes were significantly different among the six strains (p < 0.001). Differences between haplotype frequencies of the Killala and Superior strains were striking and permit greater discrimination of these strains than allozyme data. The level of differentiation observed among strains indicates that mtDNA haplotype information will enhance the ability of MSA to determine the hatchery strains that serve as parents to lake trout fry collected from Lake Ontario.
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Mayer, T., and E. Nagy. "Polycyclic Aromatic Hydrocarbons in Suspended Particulates from Hamilton Harbour." Water Quality Research Journal 27, no. 4 (November 1, 1992): 807–32. http://dx.doi.org/10.2166/wqrj.1992.049.
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Abstract The concentrations and relative abundances of sixteen priority pollutant polycyclic aromatic hydrocarbons (PAHs) were measured in suspended particulates and benthic sediments from Hamilton Harbour. The PAH concentrations in suspended particulates, often as high as PAH concentrations in benthic sediments, ranged between 4.41 and 106.02 µg/g. The highest PAH concentrations were found in areas close to the industrial sites. Selected samples of suspended particulates from western part of Lake Ontario were also analyzed for PAHs to learn about the transport of PAHs from the harbour to Lake Ontario via the Burlington Ship Canal. The results reveal export of PAHs along with the other contaminants from Hamilton Harbour to Lake Ontario. In addition to PAHs, n-alkanes were determined in all samples, as they are readily determined from the extracts and they are useful in deciphering the sources of suspended particulates, hence particle-associated PAHs.
7
Haymes, Gerard T., and Paul H. Patrick. "Exclusion of Adult Alewife, Alosa pseudoharengus Using Low-Frequency Sound for Application at Water Intakes." Canadian Journal of Fisheries and Aquatic Sciences 43, no. 4 (April 1, 1986): 855–62. http://dx.doi.org/10.1139/f86-105.
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Experiments to test the effectiveness of low-frequency, high-intensity sound in excluding alewife, Alosa pseudoharengus, from an experimental net structure were conducted on Lake Ontario near Pickering, Ont. Sound was generated by modified seismic devices called pneumatic poppers. The number of alewife entering the experimental structure was reduced by 71–99% when the poppers were operating. Sonar evidence from one test suggested that another species which was not caught in the collection nets was less influenced by the acoustic deterrent. The results suggest that low-frequency, high-intensity sound may be effective in reducing losses of adult alewife at water intakes.
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McCausland, Phil J. A., Roberta L. Flemming, Graham C. Wilson, Jim Renaud, David Dillon, and David W. Holdsworth. "The Wood Lake, Ontario, H4 ordinary chondrite, a new Canadian meteorite." Canadian Journal of Earth Sciences 50, no. 1 (January 2013): 32–43. http://dx.doi.org/10.1139/e2012-037.
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The Wood Lake meteorite was found in the Muskoka region of Ontario in July 2003. We examine the mineralogy, physical properties, shock, and weathering state of this recently reported Canadian meteorite. Bulk physical properties for Wood Lake (bulk density 3.57 ± 0.10 g/cm3, grain density 3.64 ± 0.01 g/cm3, and magnetic susceptibility log χ = 5.17) are typical of slightly weathered H chondrite falls and consistent with visual observations of its observed low weathering state (W1). Reconnaissance X-ray micro computed tomography of a Wood Lake fragment yields a similar bulk density (3.56 g/cm3) and allows for a three-dimensional description of the meteorite. Petrographic and electron probe microanalysis examination of the Wood Lake meteorite reveal sharp definition of chondrule margins, occasional mesostasis chondrule glass, only minor development of recrystallized matrix feldspar, and little variation in silicate chemical compositions, indicating Wood Lake to be an H4 ordinary chondrite. Mineral chemistry for Wood Lake olivine (Fa18.6 ± 0.7, n = 26) and low-Ca pyroxene (Fs17.5 ± 2.6, n = 16) agrees well with H chondrite averages for these minerals. The bulk of the stone has undergone a low to moderate level of shock (S3), as indicated in thin section by undulose optical extinction and the presence of planar dislocations in olivine and pyroxene grains. Moderate distortion of olivine crystal structures observed using in situ micro X-ray diffraction quantifies the shock deformation as a full width half maximum (FWHMχ) of 3.38° ± 1.13° (16 reflections from seven olivine grains), consistent with shock stage S3 ordinary chondrites. Wood Lake is confirmed as a new Canadian meteorite find that likely arrived on Earth not long before it was recovered.
9
Paterson, Andrew M., David S. Morimoto, Brian F. Cumming, John P. Smol, and Julian M. Szeicz. "A paleolimnological investigation of the effects of forest fire on lake water quality in northwestern Ontario over the past ca. 150 years." Canadian Journal of Botany 80, no. 12 (December 1, 2002): 1329–36. http://dx.doi.org/10.1139/b02-117.
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Fire is an important mechanism of disturbance in boreal ecosystems; however, the effects of fire on lake ecosystems are still not well understood. This study provides a detailed assessment of the impacts of fire on the limnology of a small oligotrophic lake (Lake 42), located approximately 200 km northwest of Thunder Bay, Ont. The study lake is characterized by a small drainage ratio (watershed area : surface area) and a relatively long water residence time. Age establishment and fire scar analyses determined that at least one, and perhaps two, major fires had burned to the lake's shoreline in the past ca. 150 years. Using a paleoecological approach, diatoms were examined in a 210Pb-dated sediment core. Following watershed fires, minimal changes were noted in the diatom species assemblage. These findings may be explained by the low sedimentation rates and small drainage ratio of the study lake, although other studies suggest that the biological response may be minimal compared with physicalchemical responses in some ecosystems. Beginning in the early 1980s, however, distinct changes were noted in the species assemblage and in diatom-inferred total phosphorus. Our findings suggest that the study lake may be more sensitive to precipitation inputs of nutrients than to inputs resulting from watershed disturbances.Key words: paleolimnology, diatoms, forest fire, water quality.
10
Hesslein, Raymond H. "Whole-Lake Metal Radiotracer Movement in Fertilized Lake Basins." Canadian Journal of Fisheries and Aquatic Sciences 44, S1 (December 18, 1987): s74—s82. http://dx.doi.org/10.1139/f87-282.
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Seven radiotracers: 75Se, 203Hg, 85Sr, 134Cs, 59Fe, 65Zn, and 60Co were added to the separated basins of Lake 226, Experimental Lakes Area, northwestern Ontario. The basins, L226N and L226S were part of an ongoing eutrophication experiment in which C, N, and P were being added to L226N and C and N to L226S. The radiotracers moved to the sediments by sorption to settling particles and by being directly absorbed. The loss rates ranged from 3–8%∙d−1. Areal distribution in the sediments was largely governed by the percent sorbed to particles. Both basins exhibited seasonal anoxic hypolimnia in which redissolution of 59Fe, 60Co, and 203Hg was great, of 75Se, 85Sr, and 65Zn only minimal, and of 134Cs negligible. The overall behavior of each of the isotopes was nearly identical in the two basins, partly due to interbasin mixing. A least squares fit of the affinity for particles and loss rates to a whole-lake model yielded a settling velocity of 0.18 m∙d−1 and a benthic boundary layer of 370 μm thickness.
11
Belontz, Sara L., Patricia L. Corcoran, Linda Kimpe, Paul A. Helm, and Chris Marvin. "A temporal record of microplastic accumulation in sediment cores of the Great Lakes, North America, reflects macroeconomic and regional influences." FACETS 9 (January 1, 2024): 1–10. http://dx.doi.org/10.1139/facets-2023-0057.
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Documented plastic pollution throughout the Laurentian Great Lakes system prompted investigation of microplastics (MPs) in sediment cores. We examined offshore sediment cores from Lake Huron (LH43) and Lake Ontario (403A) to understand temporal trends and changes in microplastic (MP) pollution in the size range 53 µm to 2 mm. MP abundances varied from 18.1 to 280.1 particles per g of dry weight sediment ( N g−1 dw) in LH43, and 8.2–488.4 g−1 dw in core 403A. The 15 cm cores are equivalent to 56 years of accumulation in Lake Huron and 72 years of accumulation in Lake Ontario. Analysis of the two cores shows an increasing trend in MP accumulation from 1964 to 1989, which mirrors the global plastic production rate. Subsequent peaks and troughs in the MP abundance profiles reflect macroeconomic changes and regional controls. These results show how changing abundances of MPs in lake sediment cores can act as proxies for global perturbations in oil supply as well as national economic shifts.
12
Dunlop, David J. "Paleomagnetism of Archean rocks from northwestern Ontario: V. Poohbah Lake alkaline complex, Quetico Subprovince." Canadian Journal of Earth Sciences 22, no. 1 (January 1, 1985): 27–38. http://dx.doi.org/10.1139/e85-003.
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The Poohbah Lake alkaline complex is a late synkinematic Kenoran pluton in the Quetico gneiss belt of the western Superior Province. Three units of the complex, porphyritic syenite (PS), malignite (M: a nepheline–clinopyroxene–K-feldspar rock), and hornblende syenite (HS), as well as baked Archean schists near the intrusive contact, have a predominantly reverse-polarity R magnetization with mean direction D = 198° I = −22.5° (k = 62, α95 = 5°, N = 13 sites) and a paleopole at 60°E, 50.5°N. Pyrrhotite and coarse primary magnetite are carriers of the R remanence. PS, M, and biotite pyroxenite (BP) exhibit also a predominantly normal N magnetization carried by fine-grained, probably secondary magnetite. N is systematically steeper than R: its mean direction is D = 359.5° I = +55.5° (k = 28, α95 = 8°, N = 13 sites) with a paleopole at 90°E, 77.5°N. R and N do not record an asymmetric field reversal, since reverse-polarity N vectors and normal-polarity R vectors are occasionally found. R resembles in polarity and direction the natural remanent magnetization (NRM) of the 2630 Ma Matachewan diabase. It is probably the primary NRM of the Poohbah Lake pluton, with an age of about 2650 Ma in approximate agreement with the K/Ar isochron age of 2700 ± 25 Ma. N resembles in polarity and direction NRM's from the 2580 Ma Shelley Lake granite and the late Archean Burchell Lake granite. It is probably a secondary NRM about 2550 Ma in age, as suggested by updated K/Ar mica ages. The characteristic NRM of HS samples and secondary magnetizations in other rock types have poles on the Grenville Track of the polar wander path but there is no evidence for Grenvillian-age events in the area.
13
Li, Lianxiang, and Sherwin S. Desser. "Three new species of Octosporella (Protozoa: Coccidia) from cyprinid fish in Algonquin Park, Ontario." Canadian Journal of Zoology 63, no. 8 (August 1, 1985): 1859–62. http://dx.doi.org/10.1139/z85-276.
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Among the protozoan parasites observed in cyprinid fish from Lake Sasajewun and Lake Opeongo, Algonquin Park, Ontario, were coccidian parasites with oocysts containing eight sporocysts, each of which housed two sporozoites. Three new species of Octosporella Ray and Raghavachari, 1942 are described: Octosporella notropis sp. n. from the intestine, spleen, and swim bladder of the common shiner, Notropis cornutus (Mitchill), and Octosporella opeongoensis sp. n. and Octosporella sasajewunensis sp. n. from the swim bladder of the golden shiner, Notemigonus crysoleucas (Mitchill). The present report represents the first time parasites of this genus have been recorded from fish.
14
Barica, J. "Ammonia and Nitrite Contamination of Hamilton Harbour, Lake Ontario." Water Quality Research Journal 25, no. 3 (August 1, 1990): 359–86. http://dx.doi.org/10.2166/wqrj.1990.019.
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Abstract The temporal and spatial distribution of total and toxic unionized ammonia, nitrite, nitrate and total dissolved nitrogen concentrations in Hamilton Harbour, Lake Ontario, were investigated during 1987–1988. The concentrations of toxic un-ionized ammonia in vertical and horizontal profiles depended on ammonia loadings from the Hamilton and Burlington municipal sewage treatment plants, the seasonal nitrogen cycle, pH and water temperature. Toxic ammonia levels in the Harbour exceeded the International Joint Commission objective of 20 μg/L at all sampling sites for about half of the year (spring and summer). For extended periods in the late spring and mid-summer, concentrations frequently exceeded the chronic toxicity threshold of 300 μg/L. Toxic un-ionized ammonia concentrations were distributed unevenly over the Harbour with a distinct areal zonation and patchiness. Volatilization of ammonia, estimated at 6.8 tonnes per summer, reduced the toxic effect but was insignificant in the overall NH3-N budget. The nitrite concentrations exceeded the chronic toxicity thresholds of 30 μg/L for most of the summer and frequently surpassed the cold-water fish toxic levels of 250 μg/L. Near the outfall from the Hamilton sewage treatment plant, nitrite levels were 600–1,200 μg/L. The frequency of nitrite toxic episodes was however lower than those of un-ionized ammonia. Nitrite was less abundant than total ammonia and can be considered as a less serious contaminant. Nitrification in Hamilton Harbour appeared to be inhibited by high toxic un-ionized ammonia levels.
15
Mills, K. H. "Responses of Lake Whitefish (Coregonus clupeaformis) to Fertilization of Lake 226, the Experimental Lakes Area." Canadian Journal of Fisheries and Aquatic Sciences 42, no. 1 (January 1, 1985): 129–38. http://dx.doi.org/10.1139/f85-016.
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The responses of an unexploited population of lake whitefish (Coregonus clupeaformis) to fertilization of Lake 226 (L226), the Experimental Lakes Area, northwestern Ontario, were measured for 4 yr (1973–77). A vinyl sea curtain separated the lake into a northeast (NE) basin, which received P, N, and C additions, and a southwest (SW) basin, which received only N and C additions. Lake whitefish in the NE basin grew faster, had higher coefficients of condition, and had greater recruitment and production than those in the SW basin during the 2nd through 4th yr of fertilization. No differences between basins were detected in annual survival for fish [Formula: see text], but survival of age 0 fish was greater in the NE basin. Whitefish production in L226NE averaged twice that in L226SW from the 2nd to the 4th yr of fertilization, though significant variations occurred between years in both the NE and SW populations.
16
Jeffries, Dean S., John R. M. Kelso, and Ian K. Morrison. "Physical, Chemical, and Biological Characteristics of the Turkey Lakes Watershed, Central Ontario, Canada." Canadian Journal of Fisheries and Aquatic Sciences 45, S1 (December 19, 1988): s3—s13. http://dx.doi.org/10.1139/f88-262.
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The Turkey Lakes Watershed (TLW) in central Ontario was selected for intensive research into the effects of the long-range transport of air pollutants (primarily acidic deposition) at a site on the Canadian Shield having both vulnerable terrain and an undisturbed Great Lakes forest type. The terrestrial and aquatic resources within the basin are representative of the surrounding region of Algoma, although for Ontario, it does have high relief (290 m) and high annual precipitation (>1200 mm). The TLW contains a chain of four lakes (five distinct lake basins) that range from 5.8 to 52.0 ha in area and 2.2 to 12.2 m in mean depth. The lakes are dimictic and, except for the deepest lake, experience dissolved oxygen depletion in undisturbed bottom waters. There is a gradient in the major ion composition of lakes within the TLW, the most dilute waters occurring at high elevations. Calcium levels increase from 55 to 138 μmol∙L−1 down the chain. Sulphate is the dominant lake water anion in the headwater lake, while alkalinity dominates in the lowest lake. Phosphorus is the limiting nutrient in these lakes; NO3-N levels are relatively high (7.9–16.4 μmol∙L−1) because the terrestrial basin exhibits low utilization of this nitrogen species. Seasonal and episodic variations in surface water composition can be large. The headwater lake contains no fish; however, fish communities in the lower three lakes (composed of 8-11 species) are typical of the Algoma region. The distribution of benthic organisms is primarily a function of lake depth and presence/absence of fish rather than variations in water chemistry. Zooplankton species composition is similar across all lakes, and cyanophytes are the dominant algae throughout. The forest is an uneven-aged, mature-to-overmature, old-growth tolerant hardwood stand. The principal tree species is sugar maple (90%) with lesser amounts of other hardwoods (9%, usually yellow birch) and various conifers (1%). Production is typical of forest at this northerly latitude (47°N). Foliar bioelement concentrations are generally similar to those observed at Hubbard Brook, New Hampshire.
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Dillon, P. J., R. D. Evans, and Lewis A. Molot. "Retention and Resuspension of Phosphorus, Nitrogen, and Iron in a Central Ontario Lake." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 7 (July 1, 1990): 1269–74. http://dx.doi.org/10.1139/f90-145.
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Sediment traps were used to estimate the downward flux of total phosphorus, total Kjeldahl nitrogen, and iron in a small Precambrian shield lake for 4 yr. The flux as determined by the sediment trap method was much higher than the retention of the same elements as measured by mass balance methods (input–outflow). Total phosphorus (TP) sedimentation was about 17 times higher than retention while N was about three times higher and Fe was about 31 times higher. Very high N/P ratios in epilimnetic waters (36/1 by weight) and low N/P ratios in trap material (8/1) and surficial sediments (mean 8/1, range 4–11/1), in conjunction with high sedimentation to retention ratios, strongly suggest that resuspended sediment is a major component of trap material. Fe/TP ratios suggest that surficial sediment from shallow waters (< 13 m) was the largest contributor to resuspended sediment. Large amounts of biologically available phosphorus originating with resuspended sediment may enter upper waters. The difference between N/P ratios in surficial sediments (4–11/1) and nutrients retained from mass balance calculations (50/1) is attributed to denitrification.
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Chan, Vincy, Brandon Zagorski, Daria Parsons, and Angela Colantonio. "Older Adults with Acquired Brain Injury: Outcomes After Inpatient Rehabilitation." Canadian Journal on Aging / La Revue canadienne du vieillissement 32, no. 3 (August 6, 2013): 278–86. http://dx.doi.org/10.1017/s0714980813000317.
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RÉSUMÉCette étude a examiné un profil basé sur la population des personnes âgées atteintes des lésions cérébrales acquises (LCA), et de leur résultats fonctionnels, en réadaptation en milieu hospitalier au Canada. Les personnes âgées de 65 ans et plus qui ont été admises en réadaptation en milieu hospitalier de soins aigus pour un traumatisme cranio-cérébrale (TCC) (n = 1 214) ou une lésion cérébrale non pas traumatique (nTCC) (n = 1 530) ont été identifiées en Ontario de 2003/04 à 2009/10. Les caractéristiques démographiques et cliniques et les notes fonctionnelles totales de l’instrument (FIMMD) ont eté examinées. On a utilisé le Base de données sur les congés des patients (BDCP) et le Système nationale d’information sur la réadaptation (SNIR). Les résultats ont montré que les personnes plus âgées atteintes d’un traumatisme cranio-cérébrale (TCC) présentaient un niveau d’indépendence fonctionelle plus élevé que celles sans TCC à l’admission et à la sortie. Cependant, les deux groupes ont faits des gains importants (p = .001) et similaires (p > .05). Nous concluons que les personnes âgées avec TCC et nTCC font des gains similaires de réadaptation en milieu hospitalier. L’incapacité fonctionnelle initiale plus faible des patients nTCC à l’admission et les profils cliniques différents offrent des implications pour la répartition des soins et des ressources cliniques.
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Beis, M. J., and D. K. Cone. "A report of Thelohanellus notatus (Mavor) (Myxozoa) from Notropis hudsonius (Clinton) (Cyprinidae) in Ontario." Canadian Journal of Zoology 68, no. 3 (March 1, 1990): 602–3. http://dx.doi.org/10.1139/z90-087.
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Thelohanellus notatus (Mavor) is reported from young of the year Notropis hudsonius (Clinton) (Cyprinidae) in Lake Mindemoya, Manitoulin Island, Lake Huron, Ontario. The parasite produced large cysts (1–5 mm in diameter) in body musculature and mesenteries, with aggregations occurring at the base of fins. Forty-six of 47 fish were infected. Intensity was unusually high at 2–30 cysts per fish. The study is the first report of the parasite from Manitoulin Island and from N. hudsonius.
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Daly, Tamara, Albert Banerjee, Pat Armstrong, Hugh Armstrong, and Marta Szebehely. "Lifting the ‘Violence Veil’: Examining Working Conditions in Long-term Care Facilities Using Iterative Mixed Methods." Canadian Journal on Aging / La Revue canadienne du vieillissement 30, no. 2 (June 2011): 271–84. http://dx.doi.org/10.1017/s071498081100016x.
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RÉSUMÉLe présent document se concentre sur les méthodes mixtes nous avons utilisé pour comprendre conditions de travail de leur travailleurs dans les établissements de soins de longue durée. Nous avons mené une enquête auprès des syndiqués travailleurs de santé en Ontario (n= 917), et une autre enquête dans trois provinces (n= 948) et quatre pays Scandinaves (n= 1625). Neuf groupes de discussion avec les Canadiens ont eu lieu; les répondants ont été présentés avec des questions du sondage et aussi descriptive des résultats statistiques et ont été demandé: “Est-ce le reflet de votre expérience?” Les contraintes de temps pour les travailleurs et la fréquence des expériences des travailleurs de la violence physique et attentions sexuelles non désirées sont signalés. Nous discutons comment de le façon dont nous utilisé des méthodes qualitatives et quantitatives étè itératif. Nous avons trouvé pas seulement la cohérence des données mais aussi la divergence des données qui montrent comment une culture de la violence dans les établissements de soins de longue durée est acceptée par les travailleurs comme d’habitude. Comment le constat de la violence structurelle vu le jour et la signification profonde, le contexte et les idées qui proviennent de la combinaison de nos méthodes itératives sont discutées.
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Farmer Jr., Robert E., Gwenoth O'Reilly, and Deng Shaotang. "Genetic variation in juvenile growth of tamarack (Larixlaricina) in northwestern Ontario." Canadian Journal of Forest Research 23, no. 9 (September 1, 1993): 1852–62. http://dx.doi.org/10.1139/x93-235.
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Nested designs incorporating provenances and families and clones within provenances were used in two common garden tests near Thunder Bay, Ont. (48°N, 84°W) to evaluate genetic variation in growth and sylleptic branching among and within populations of tamarack (Larixlaricina (Du Roi) K. Koch) from 46°N, 80°W to 53°N, 93°W. At 7 and 8 years there was a north-south trend of increasing height among provenances. Genetic variation in height was related to both rate and duration of shoot elongation, but latitudinal variation in shoot growth mainly resulted from differences in late-season elongation. There was substantial genetic variance in height within populations, and broad-sense heritability based on pooled variances was 0.23 for one test population at 8 years and 0.11 for the second at 7 years. The more vigorous southern provenances had a greater potential for sylleptic branching in the test area than northern sources, and wide within-population variation in syllepsis was under stronger genetic control than growth (broad-sense heritability = 0.47 in year 6). Patterns of genetic variation observed in the study were not congruent with patterns of morphological and allozyme variation previously reported for the sampled populations.
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Brubacher, Laura Jane, Matthew Little, Abby Richter, and Warren Dodd. "Le rôle de la prescription d’aliments frais dans le contexte des services sociaux : une étude qualitative en Ontario (Canada)." Promotion de la santé et prévention des maladies chroniques au Canada 44, no. 6 (June 2024): 298–308. http://dx.doi.org/10.24095/hpcdp.44.6.03f.
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Introduction Les programmes de prescription alimentaire, qui font partie du mouvement de la prescription sociale, sont une stratégie de lutte contre l’insécurité alimentaire et l’alimentation sous-optimale dans les établissements de soins de santé. Ces programmes sont offerts conjointement à d’autres services sociaux, en particulier les mesures de soutien fondées sur le revenu et les programmes d’aide alimentaire, sans que les interactions entre ces programmes et les services préexistants aient été suffisamment évaluées. Cette étude, qui a été menée dans le cadre l’évaluation d’un programme de prescription alimentaire de 52 semaines intitulé Fresh Food Prescription (FFRx) (avril 2021 à octobre 2022), vise à déterminer la manière dont l’adhésion au programme a transformé l’attitude des participants envers les mesures de soutien fondées sur le revenu et les programmes d’aide alimentaire. Méthodologie Cette étude a été menée à Guelph (Ontario, Canada). Des entrevues individuelles (n = 23) et des entrevues de suivi (n = 10) ont été réalisées pour explorer les expériences des participants en lien avec le programme. Des données qualitatives ont été étudiées par thème au moyen d’une analyse comparative constante. Résultats Les participants ont décrit leur expérience du programme FFRx en relation avec les mesures de soutien fondées sur le revenu et les programmes d’aide alimentaire déjà en place. Le programme FFRx semble avoir accru leur revenu disponible pour les frais de subsistance, permis aux participants de consacrer leur revenu à d’autres besoins et réduit les sacrifices nécessaires pour répondre à leurs besoins de base. Ce programme a diminué la fréquence du recours aux autres programmes d’aide alimentaire. Certaines spécificités du programme FFRx (comme la livraison de nourriture) lui ont valu la préférence des participants par rapport aux autres mesures d’aide alimentaire. Conclusion À mesure que d’autres programmes de prescription alimentaire et de prescription sociale vont être mis au point, il est essentiel d’évaluer comment ces initiatives entrent en interaction avec les services déjà en place et comment elles renforcent et influencent les services sociaux en général.
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Kaufman, Scott D., Ed Snucins, John M. Gunn, and Wayne Selinger. "Impacts of road access on lake trout (Salvelinus namaycush) populations: regional scale effects of overexploitation and the introduction of smallmouth bass (Micropterus dolomieu)." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 2 (February 2009): 212–23. http://dx.doi.org/10.1139/f08-205.
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In lake trout ( Salvelinus namaycush ) lakes of northeastern Ontario, Canada, aerial surveys of fishing activity on individual lakes (N = 589) and quantitative gillnet surveys (N = 65) were used to assess the effects of road access on angling effort and the presence of introduced smallmouth bass ( Micropterus dolomieu ). Angling effort, particularly during the open-water season, was highest and often exceeded estimated sustainable levels on lakes with good road access. Approximately 25% of the remote lakes also received excessive pressure during the winter season. Angler numerical responses to lake trout abundance were detected in remote lakes, but not in road-accessible lakes. Smallmouth bass were more prevalent in lakes with road access and human settlement (either cottages or lodges), supporting the theory that they were introduced into these lakes. Lake trout populations were depleted throughout much of the study range. Even without road access or smallmouth bass, lake trout abundance was still 47% lower than in unexploited reference lakes. When bass and (or) road access were present, lake trout abundance decreased by 77%. Remote lake trout populations in this area are clearly vulnerable to the negative impacts of improved access, a vector for both overexploitation and species introductions.
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Levitt, Anthony J., and Michael H. Boyle. "The Impact of Latitude on the Prevalence of Seasonal Depression." Canadian Journal of Psychiatry 47, no. 4 (May 2002): 361–67. http://dx.doi.org/10.1177/070674370204700407.
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Background: This study sought to determine whether the prevalence of the seasonal subtype of major depression (SAD) in the community varied as a function of latitude. Methods: Random telephone numbers were generated across 8 degrees of latitude (41.5 °N to 49.5°N) for the province of Ontario. Eight strata of 1 degree each were sampled equally throughout a 12-month period. Using a validated and structured diagnostic interview, we interviewed by telephone respondents over 20 years of age who had lived in the region for 3 years or more. We evaluated patterns of symptom change across seasons to establish a diagnosis of SAD according to DSM-IV criteria. Results: Of the 2078 households that were assessed for eligibility, 1605 (77%) completed the interview. The crude prevalence of lifetime SAD was 2.6% (95% CI, 1.9 to 3.5). There was no impact of latitude on prevalence of either major depression or the seasonal subtype across the 8 strata, although the global measure of the severity of seasonal change in mood was significantly negatively correlated with latitude. Conclusions: SAD is a common subtype of major depression in Ontario, but there is no evidence to support an increase in prevalence with increasing latitude. Contexte: Cette étude visait à déterminer si la prévalence du caractère saisonnier de la dépression majeure (DMS) dans la communauté variait selon la latitude. Méthodes: Des numéros de téléphone aléatoires ont été fournis sur 8 degrés de latitude (de 41,5°N. à 49,5°N.) dans la province de l'Ontario. Huit bandes de 1 degré chacune ont été échantillonnées également sur une période de 12 mois. À l'aide d'une entrevue diagnostique validée et structurée, nous avons interviewé par téléphone des répondants âgés de plus de 20 ans qui habitaient la région depuis 3 ans ou plus. Nous avons évalué les changements des modèles de symptômes selon les saisons pour établir un diagnostic de DMS selon les critères du DSM-IV. Résultats: Sur les 2 078 ménages admissibles, 1 605 (77 %) ont terminé l'entrevue. La prévalence brute de la DMS à vie était de 2,6 % (95 % IC, 1,9 à 3,5). La latitude n'influait pas sur la prévalence de la dépression majeure ou du caractère saisonnier dans les 8 bandes, bien que la mesure globale de la sévérité du changement saisonnier de l'humeur ait indiqué une corrélation négative significative à la latitude. Conclusions: La dépression majeure saisonnière est un sous-type répandu de la dépression majeure en Ontario, mais aucune preuve ne soutient une augmentation de la prévalence parallèle à l'accroissement de la latitude.
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Abara, Erinma, Miya Narushima, and Emmanuel O. Abara. "Patterns of computer and Internet usage among urology patients in two rural Northern Ontario communities." Canadian Urological Association Journal 4, no. 1 (April 16, 2013): 37. http://dx.doi.org/10.5489/cuaj.772.
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Introduction: We wanted to determine if the Internet can be usedas a potential health promotion tool among urology patients inNorthern Ontario. We identified patients’ computer and Internetaccess and use patterns in Kirkland Lake and Kapuskasing, Ontario.Materials and Methods: This study was reviewed and approved bythe ethics boards of the Kapuskasing and Kirkland Lake hospitalsand Brock University. Data were collected by hand-written questionnairesin English and French. We performed a descriptiveanalysis of the data obtained.Results: Out of the 137 questionnaires distributed and collected,we achieved a 95% response rate (7 questionnaires were incomplete).There were 67 men (52 %) and 63 women (48%) rangingin age from 24 to 84 (mean 56). Languages spoken were English(57%), French (38%) and other (5%). We divided the responsesinto 3 groups: non-Internet users, those with a computer but noInternet access and Internet users. Internet and non-Internet userswere studied. Our results indicated that younger respondents, thosewith higher education and higher paying jobs, used the computerand Internet more often. The main reason behind their Internetwas to seek health information for themselves, family and friends.Conclusion: About half of the respondents (55%) used the Internetto access health information. Patients’ reactions toward onlinecommunication with their family physician were mixed. One limitationof this study is the small sample size, which inhibits makingfar-reaching conclusions. Our results demonstrate that individualempowerment, access to health information and access toservices via emerging technologies are important issues for urologypatients in rural Northern Ontario.Introduction : Nous avons cherché à déterminer si Internet peut êtreutilisé comme outil potentiel de promotion de la santé chez despatients en urologie dans le Nord de l’Ontario. Nous avons vérifiél’accès à un ordinateur et à Internet et les schémas d’utilisation depatients des régions de Kirkland Lake et de Kapuskasing (Ontario).Matériel et méthodologie : L’étude a été revue et approuvée par lescomités d’éthique des hôpitaux de Kapuskasing et de Kirkland Lakeet de la Brock University. Les données ont été recueillies à l’aidede questionnaires remplis à la main en anglais et en français. Nousavons ensuite procédé à une analyse descriptive des données.Résultats : Sur les 137 questionnaires distribués et retournés, nousavons obtenu un taux de réponse de 95 % (7 questionnaires n’ontpas été remplis). Les répondants comptaient 67 hommes (52 %) et63 femmes (48 %) dont l’âge variait entre 24 et 84 ans (moyennede 56 ans). Les langues parlées étaient l’anglais (57 %), le français(38 %) et d’autres langues (5 %). Nous avons divisé les réponsesen trois groupes : ceux qui n’utilisent pas Internet, ceux qui ontaccès à un ordinateur mais aucun accès à Internet et ceux qui utilisentInternet. Les patients utilisant ou n’utilisant pas Internet ont étéétudiés. Nos résultats indiquent que les répondants plus jeunes,ayant un niveau de scolarité plus élevé et des emplois mieuxrémunérés utilisent l’ordinateur et Internet plus souvent. La principaleraison de l’emploi d’Internet était la recherche d’informationsmédicales pour eux-mêmes, pour leur famille et leurs amis.Conclusion : Environ la moitié des répondants (55 %) utilisaientInternet pour trouver des renseignements sur la santé. Les réactionsdes patients vis-à-vis la communication en ligne avec leurmédecin de famille étaient mitigées. Les résultats de l’étude sontlimités par la petite taille de l’échantillon, ce qui empêche detirer des conclusions profondes. Nos résultats montrent que laresponsabilisation individuelle et l’accès à des renseignements etdes services de nature médicale par le biais des nouvelles technologiessont des points importants pour les patients en urologiedans les régions rurales du Nord de l’Ontario.
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Thomson, Ashley M., Claire L. Riddell, and William H. Parker. "Boreal forest provenance tests used to predict optimal growth and response to climate change: 2. Black spruce." Canadian Journal of Forest Research 39, no. 1 (January 2009): 143–53. http://dx.doi.org/10.1139/x08-167.
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Height, diameter, and survival data were obtained from 20 range-wide black spruce ( Picea mariana (Mill.) BSP) provenance trials established from 1973 to 1977. Population response functions based on February minimum temperatures were developed for 23 Ontario and Great Lakes states provenances to predict climate values maximizing height growth for individual seed sources. Site transfer functions based on February maximum temperatures and May maximum temperatures were developed for five test sites to predict climate values maximizing height growth for test locations. Contour lines representing optimal performance were fitted to current (1961–1990) and future (2041–2070) climate grids. For black spruce seed sources from the east of Lake Superior and Lake Huron, optimal height growth was achieved between 45° and 47°N; for the western sources optimal performance moved north between 46° and 48°N. In eastern Ontario, height growth of northern sources may increase with transfer to warmer environments and with future temperature increases. Central sources are currently growing at or close to optimum and will be negatively affected by increased future temperatures. Southern sources may currently benefit from transfer to cooler environments, and the effects of global warming may cause significant height growth loss and the potential extirpation of local populations.
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Krueger, Andrea M., and Francine M. G. McCarthy. "Great Canadian Lagerstätten 5. Crawford Lake – A Canadian Holocene Lacustrine Konservat-Lagerstätte with Two-Century-Old Viable Dinoflagellate Cysts." Geoscience Canada 43, no. 2 (May 18, 2016): 123. http://dx.doi.org/10.12789/geocanj.2016.43.086.
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In addition to commonly preserved microfossils like pollen and diatoms, the varved sediments of Crawford Lake, Ontario, contain the fossilized remains of otherwise rare microfossils. Bottom water anoxia resulted from the physiography of this small, deep lake and enhanced biochemical oxygen demand (BOD) during two distinct phases of human settlement: prehistoric Iroquoian (approximately 1268–1486 CE) and historic Euro-Canadians (since 1822 CE). The exceptional preservation of delicate organic-walled microfossils like rotifer loricae and cellulosic dinoflagellate thecae provides unparalleled insights into a Holocene freshwater lake ecosystem and allows the biological and taphonomic components of the fossil assemblage to be isolated. Bottom water anoxia may also have increased the longevity of cell contents: resting cysts of Parvodinium [Peridinium] inconspicuum (Lemmermann) Carty and Peridinium volzii Lemmermann. These were germinated from varves deposited nearly two centuries ago, extending the known span of viability of dinoflagellates.RÉSUMÉEn plus des microfossiles couramment conservés comme le pollen et les diatomées, les sédiments varvés du lac Crawford en Ontario, contiennent les restes fossilisés de microfossiles très rares. Le caractère anoxique des eaux de fond s’explique par la physiographie de ce petit lac profond et par une augmentation de la demande biochimique en oxygène (DBO) durant deux phases distinctes de peuplement humain : phase préhistorique iroquoienne (environ 1268 à 1486 CE) et une phase historique euro-canadienne (depuis 1822 CE). La préservation exceptionnelle de délicats microfossiles à membranes organiques comme rotifère lorica et les thèques cellulosiques de dinoflagellés, ouvre une fenêtre inédite sur l’écosystème d’un lac d’eau douce Holocène et permet aux composants biologiques et taphonomiques de l'assemblage de fossiles d'être préservés isolément. L’anoxie des eaux de fond peut également avoir augmenté la longévité du contenu des cellules: kystes dormants de Parvodinium [Peridinium] inconspicuum (Lemmermann) Carty et de Peridinium volzii Lemmermann. Ces derniers ont été activés à partir de varves déposés il y a près de deux siècles, ce qui allonge la durée connue de la viabilité des dinoflagellés.
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Fee, E. J., R. E. Hecky, G. W. Regehr, L. L. Hendzel, and P. Wilkinson. "Effects of Lake Size on Nutrient Availability in the Mixed Layer during Summer Stratification." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 12 (December 1, 1994): 2756–68. http://dx.doi.org/10.1139/f94-276.
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Fluxes to the summer mixed layer of N, Si, and P were estimated in a size series of northwestern Ontario Canadian Shield lakes. Increasing turbulence caused upward fluxes through the thermocline to increase with lake size for nutrients that increased in concentration below the thermocline (soluble reactive Si, total inorganic N, and NO3−; but not total N or any form of P). Precipitation and terrestrial runoff were equally important sources of N and P in all but very small lakes (< 100 ha), where precipitation supplied much more than runoff. Runoff was the only important source of Si, except in very large lakes (> 100 000 ha) where mixing through the thermocline was important. N2-fixation was unimportant except in intermediate-sized fakes (700–2000 ha). Si fluxes nearly equaled phytoplankton requirements, but N and P were below requirements, and recycling within the mixed layer must be the most important source of these nutrients. N and P deficits increased progressively with lake size, implying that the efficiency of nutrient recycling increased with lake size; mixed layers in large lakes are more turbulent and thicker than in small lakes and these processes increase the probability of nutrient regeneration within the mixed layer.
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Zhang, Kevin, Avika Misra, Patrick J. Kim, Seyed M. Moghadas, Joanne M. Langley, and Marek Smieja. "Disparition rapide de la grippe après la mise en œuvre de mesures d'atténuation de la COVID-19 à Hamilton, Ontario." Relevé des maladies transmissibles au Canada 47, no. 04 (May 7, 2021): 221–27. http://dx.doi.org/10.14745/ccdr.v47i04a04f.
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Contexte : Des mesures de santé publique, telles que la distanciation physique et la fermeture des écoles et des services non essentiels, ont été rapidement mises en œuvre au Canada pour freiner la propagation de la maladie à coronavirus 2019 (COVID-19). Nous avons cherché à étudier les conséquences des mesures d'atténuation pendant la vague printanière de COVID-19 sur l'incidence d'autres virus respiratoires confirmés en laboratoire à Hamilton, en Ontario. Méthodes : Tous les échantillons d'écouvillons nasopharyngés (n = 57 503) soumis à un dépistage systématique du virus respiratoire dans un laboratoire régional desservant tous les centres hospitaliers de soins de courte durée de Hamilton entre janvier 2010 et juin 2020 ont été examinés. Les tests de dépistage de la grippe A et B, du virus respiratoire syncytial, du métapneumovirus humain, du virus para-influenza I-III, de l'adénovirus et du rhinovirus/entérovirus ont été effectués systématiquement à l'aide d'un panel multiplex de virus respiratoires par réaction en chaîne par polymérase mis au point par le laboratoire. Un modèle de régression linéaire bayésien a été utilisé pour déterminer la tendance des taux de positivité de tous les échantillons de grippe au cours des 26 premières semaines de chaque année de 2010 à 2019. Le taux de positivité moyen de l'inférence bayésienne a été comparé au taux de positivité hebdomadaire des échantillons de grippe rapporté en 2020. Résultats : Le taux de positivité de la grippe en 2020 a fortement diminué après la mise en œuvre d’interventions relatives à la COVID-19 à l'échelle de la population. Les semaines 12–26 ont rapporté 0 % de positivité pour la grippe, à l'exception de 0,1 % rapporté la semaine 13. Conclusion : Les mesures de santé publique mises en œuvre pendant la pandémie de COVID-19 ont été associées à une incidence réduite d'autres virus respiratoires et devraient être envisagées pour atténuer la gravité de la grippe saisonnière et des pandémies dues à d'autres virus respiratoires.
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Kidd, Karen A., Michael J. Paterson, Raymond H. Hesslein, Derek CG Muir, and Robert E. Hecky. "Effects of northern pike (Esox lucius) additions on pollutant accumulation and food web structure, as determined by δ13 C and δ15 N , in a eutrophic and an oligotrophic lake." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 11 (November 1, 1999): 2193–202. http://dx.doi.org/10.1139/f99-148.
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In May 1993 and 1994, northern pike (Esox lucius) were added to eutrophic Lake 227 and oligotrophic Lake 110 at the Experimental Lakes Area in northwestern Ontario. Both lakes were previously dominated by cyprinids, and northern pike additions significantly decreased cyprinid densities in both lakes. Food web relationships were determined pre- and post-manipulation using stable carbon (δ13C) and nitrogen (δ15N) isotope analyses of zooplankton, benthic invertebrates, and fishes. In Lake 110, fathead minnow (Pimephales promelas) shifted from a zooplanktivorous to a zoobenthivorous diet as indicated by a shift in isotopic composition to more depleted δ15N and enriched δ13C values after northern pike additions. It was not possible to direct predator-induced shifts in cyprinid diets in Lake 227. Concentrations of mercury and organochlorines (sum of polychlorinated biphenyls (ΣPCB), dichlorodiphenyltrichloroethane (ΣDDT), and hexachlorocyclohexane (ΣHCH)) in these fish did not change markedly after northern pike introductions despite the shifts in diet for fathead minnow from Lake 110. However, concentrations of all contaminants were lower in biota from eutrophic Lake 227 when compared with Lake 110, which is consistent with previous studies. Our results indicate that nutrient availability, rather than short-term changes in food web structure, determined contaminant concentrations in fish and other biota from these lakes.
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Burden, Elliott T., John H. McAndrews, and Geoffrey Norris. "Palynology of Indian and European forest clearance and farming in lake sediment cores from Awenda Provincial Park, Ontario." Canadian Journal of Earth Sciences 23, no. 1 (January 1, 1986): 43–54. http://dx.doi.org/10.1139/e86-005.
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Palynologic analyses of four short cores collected along shallow- to deep-water transects in Second and Gignac lakes indicate two periods of forest clearance for farming. The first deforestation was by Huron Indians between A.D. 1450 and 1650, when a maple (Acer), beech (Fagus), and oak (Quercus) forest was cleared and corn (Zea) planted. This disturbance is identified by decreased tree pollen and increased Pteridium, Artemisia, and other herbs and is confirmed by Zea pollen in Gignac Lake. From 1650 to 1875 there was a forest succession to oak, birch (Betula), and pine (Pinus). Following this recovery European loggers and farmers cleared this forest and attempted farming. Besides a reduction in tree pollen, a product of this deforestation includes the pollen of weedy Ambrosia, Gramineae, and introduced European Rumex and Plantago. During the last 25 years an increase in tree pollen indicates local forest recovery consistent with present land use.By relating upland vegetation successions to lacustrine algal assemblage changes, probable ecological controls on algae during the last 600 years are identified. Peridinium willei Huitfeldt-Kaas and Pediastrum respond to changes induced by forest clearance and agriculture. Aquadulcum awendae n. sp. and Peridinium wisconsinense Eddy prefer less alkaline water.Variations in palynomorph influx are related to basin morphology and water circulation. Gignac Lake, a steep sided and relatively deep lake, directs palynomorphs from shallow marginal banks to the deeper basin, whereas Second Lake, with a gently sloping shallow lake bottom, preferentially accumulates palynomorphs close to shore.
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Mumby, James A., Timothy B. Johnson, Thomas J. Stewart, Edmund A. Halfyard, Brian C. Weidel, Maureen G. Walsh, Jana R. Lantry, and Aaron T. Fisk. "Feeding ecology and niche overlap of Lake Ontario offshore forage fish assessed with stable isotopes." Canadian Journal of Fisheries and Aquatic Sciences 75, no. 5 (May 2018): 759–71. http://dx.doi.org/10.1139/cjfas-2016-0150.
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The forage fish communities of the Laurentian Great Lakes continue to experience changes that have altered ecosystem structure, yet little is known about how they partition resources. Seasonal, spatial, and body size variation in δ13C and δ15N was used to assess isotopic niche overlap and resource and habitat partitioning among the five common offshore Lake Ontario forage fish species (n = 2037; alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), round goby (Neogobius melanostomus), and deepwater (Myoxocephalus thompsonii) and slimy (Cottus cognatus) sculpins). Round goby had the largest isotopic niche (6.1‰2, standard ellipse area), followed by alewife (3.4‰2), while rainbow smelt, slimy sculpin, and deepwater sculpin had the smallest and similar niche size (1.7‰2–1.8‰2), with only the sculpin species showing significant isotopic niche overlap (>63%). Stable isotopes in alewife, round goby, and rainbow smelt varied with location, season, and size, but did not vary in the sculpin species. Lake Ontario forage fish species have partitioned food and habitat resources, and non-native alewife and round goby have the largest isotopic niche, suggestive of a boarder ecological niche, and may contribute to their current high abundance.
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Barber, M. Craig, Luis A. Suárez, and Ray R. Lassiter. "Modelling Bioaccumulation of Organic Pollutants in Fish with an Application to PCBs in Lake Ontario Salmonids." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 2 (February 1, 1991): 318–37. http://dx.doi.org/10.1139/f91-044.
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A model describing passive accumulation of organic chemicals from the aqueous environment and contaminated food in fish is developed. This model considers both biological attributes of the fish and physicochemical properties of the chemical that determine diffusive exchange across gill membranes and intestinal mucosa. Important biological characteristics addressed by the model are the fish's gill morphometry, feeding and growth rate and fractional aqueous, lipid, and nonlipid organic composition. Relevant physicochemical properties are the chemical's molar volume and n-octanol/water partition coefficient (Kow), which are used to estimate the chemical's aqueous diffusivity and partitioning to the fish's lipid and nonlipid organic fractions respectively. The model is used to describe and to analyze the bioaccumulation of polychlorinated biphenyls (PCBs) in Lake Ontario alewife (Alosa pseudoharengus), coho salmon (Oncorhynchus kisutch), rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), and lake trout (Salvelinus namaycush).
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Venkiteswaran, J. J., S. L. Schiff, M. J. Paterson, N. A. P. Flinn, H. Shao, and R. J. Elgood. "Changing nitrogen deposition with low δ15N−NH4 + and δ15N−NO3 − values at the Experimental Lakes Area, northwestern Ontario, Canada." FACETS 2, no. 1 (May 1, 2017): 249–66. http://dx.doi.org/10.1139/facets-2016-0060.
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Ammonium deposition at the International Institute for Sustainable Development Experimental Lakes Area (IISD–ELA), in northwestern Ontario, Canada, has doubled in the last 45 years and thus is no longer among the low nitrogen (N) deposition sites in North America. This may be related to the concurrent intensification of Manitoba agriculture to the west and upwind of the ELA. Large increases in ammonium deposition at the ELA were important in driving the observed trend and increased the NH4 + to NO3 − ratio of input to aquatic and terrestrial systems. Stable isotope analyses of two years of bulk (wet and dry) atmospheric deposition revealed very large ranges in δ15N−NH4 + (22‰ range), δ15N−NO3 − (18‰), and δ18O–NO3 − (19‰). Few other δ15N−NH4 +, δ15N−NO3 −, and δ18O–NO3 − values have been published for Canadian precipitation. Increases in δ15N of NH4 + and NO3 − in July occurred with increases in total N deposition. The wide range and seasonal trends of δ15N and δ18O values in ELA precipitation mean that studies characterizing N inputs to watersheds and lakes require an ongoing and comprehensive annual sampling regime. Global trends of declining δ15N of N deposition evident in lake sediment records may be a result of increases in NH4 + deposition with lower δ15N−NH4 + values. Similarly, the relationship in Lake Superior between increasing NO3 − and lower δ15N−NO3 − values may be explained by increased atmospheric deposition of N with low δ15N values.
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Edge, T. A., I. U. H. Khan, R. Bouchard, J. Guo, S. Hill, A. Locas, L. Moore, et al. "Occurrence of Waterborne Pathogens and Escherichia coli at Offshore Drinking Water Intakes in Lake Ontario." Applied and Environmental Microbiology 79, no. 19 (July 8, 2013): 5799–813. http://dx.doi.org/10.1128/aem.00870-13.
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ABSTRACTThe occurrence of waterborne pathogens was investigated at three drinking water intakes located about 2 km offshore in Lake Ontario. Water sampling was conducted over 3 years forCampylobacterspp.,Cryptosporidiumspp.,Giardiaspp., cultivable enteric viruses, and water quality parameters. All pathogens were detected in the offshore source water for each water treatment plant (WTP1 to WTP3), although at relatively low frequencies and concentrations.Giardiawas the most common pathogen, occurring in 36% of water samples from the influent of WTP1 (n= 46), and with a maximum concentration of 0.70 cysts/liter in this influent.Cryptosporidiumoccurred as frequently as 15% in the WTP2 influent (n= 35), with a maximum concentration of 0.40 oocysts/liter in the WTP1 influent. The humanBacteroidalesHF183 DNA marker was most common in the WTP1 influent (19%), and this was the only WTP where theCryptosporidium hominisgenotype was detected. No water quality parameter was predictive of pathogen occurrence across all three WTP influents.Escherichia coliwas often below detection when pathogens were detected, and spikes inE. coliconcentrations often did not coincide with pathogen occurrence. After summer rain events, river plumes hadE. coliconcentrations as high as 222 CFU/100 ml in surface waters 2 km offshore, without impacting drinking water intakes below the thermocline on the lake bottom. At times, prechlorination to control mussels at offshore intake cribs compromised the use ofE. colifor “raw” water quality assessment, particularly for chlorine-resistantCryptosporidium. E. colimeasured by standard methods did not reliably predict pathogen occurrence at drinking water intakes in offshore ecosystems.
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King, E. M., J. W. Valley, and D. W. Davis. "Oxygen isotope evolution of volcanic rocks at the Sturgeon Lake volcanic complex, Ontario." Canadian Journal of Earth Sciences 37, no. 1 (April 1, 2000): 39–50. http://dx.doi.org/10.1139/e99-106.
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Igneous zircons from the Sturgeon Lake volcanic complex, host to several massive sulphide deposits in the Superior Province, Canada, have an average δ18O(zircon) of 5.4 ± 0.3 VSMOW (n = 9 rocks). These zircons are from units differing in age by 18 million years in the 2.7 Ga complex. There is no detectable interaction of high δ18O, supracrustal lithologies in the magma. Quartz from volcanic units beneath the largest ore body, the Mattabi deposit, has an average δ18O of 9.3 ± 0.6. Quartz phenocrysts from the Mattabi unit and overlying volcanics have elevated and heterogeneous δ18O values averaging 13.8 ± 0.9 and are not in magmatic equilibrium with zircons. The δ18O values of whole-rock powders range from 5.6 to 14.3 and follow the trend observed in the δ18O values of quartz. Healed microcracks are visible in cathodoluminescence images (but are not obvious optically) of quartz phenocrysts from units with high δ18O values and disequilibrium Δ(quartz-zircon) suggesting that recrystallization facilitates the elevation of δ18O. Quartz phenocrysts from volcanic units with Δ(quartz-zircon) values near equilibrium at magmatic temperatures do not display healed microcracks in cathodoluminescence. The elevated δ18O(quartz) values are not restricted to units hosting orebodies, but are seen in all rocks in the volcanic stratigraphy that postdate eruption of the Mattabi unit. Oxygen isotope ratios combined with physical volcanology studies suggest that impermeable volcanic layers control the size and location of the many hydrothermal systems that may have occurred in the Sturgeon Lake complex.
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Kehoe, F. Patrick, and C. Davison Ankney. "Variation in digestive organ size among five species of diving ducks (Aythya spp.)." Canadian Journal of Zoology 63, no. 10 (October 1, 1985): 2339–42. http://dx.doi.org/10.1139/z85-346.
Full textAbstract:
Ceca length, small intestine length, and gizzard weight were measured for individuals of five species of diving ducks collected at Long Point Bay, Lake Erie, and Mitchell's Bay, Lake St. Clair, Ontario, in the falls of 1982 and 1983. The five species were Lesser Scaup (Aythya affinis, N = 84), Ring-necked Duck (Aythya collaris, N = 57), Greater Scaup (Aythya marila, N = 54), Redhead (Aythya americana, N = 58), and Canvasback (Aythya valisineria, N = 112). The diets of these species reportedly differ in diversity as well as in amount of fibre, and interspecific differences in gut morphology, not explained by differences in body weight, were accounted for by general differences in diet. Canvasbacks, although the heaviest species, had the shortest ceca, short intestines and light gizzards, presumably because their diet contains the least fibre. Conversely, the relatively small-bodied scaup species had the longest small intestines, likely because of their diverse diets which include animal and plant material. Our results show that morphological differences in waterfowl guts reflect dietary differences at a particular time and location and also illustrate the importance of adjusting gut measurements to body weight before making interspecific comparisons.
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McQueen, D. J., and D. R. S. Lean. "Influence of Water Temperature and Nitrogen to Phosphorus Ratios on the Dominance of Blue-Green Algae in Lake St. George, Ontario." Canadian Journal of Fisheries and Aquatic Sciences 44, no. 3 (March 1, 1987): 598–604. http://dx.doi.org/10.1139/f87-073.
Full textAbstract:
Data collected at Lake St. George, Ontario, over five summers spanning a period of 13 yr showed that there was no correlation between percent blue-green algal composition and the ratio of total nitrogen (TN) to total phosphorus (TP), However, percent blue-green algae was positively correlated with temperature and negatively correlated with nitrate nitrogen (NO3-N), total inorganic nitrogen (TIN), and the ratio of NO3-N:TP. Multiple correlations involving percent blue-green algae (dependent variable) with respect to temperature, in combination with one of NO3-N, TIN, NO3-N:TP, or TIN:TP, were also significant. In all cases, temperature effects accounted for most of the explained variation. The strongest correlation was found for the multiple regression involving percent blue-green algae versus temperature and the NO3-N: TP ratio. The pattern that emerged from the Lake St. George data set was that when temperature exceeded 21 °C and the ratio of NO3-N:TP was below 5:1, the likelihood of a blue-green algal bloom was high. When temperature was below 21 °C and NO3-N:TP exceeded 5:1, blue-green blooms never occurred.
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Evans, B., and P. Laughton. "EMERGING TRENDS IN ELECTRICAL ENERGY USAGE AT CANADIAN (ONTARIO) MUNICIPAL WASTEWATER TREATMENT FACILITIES AND STRATEGIES FOR IMPROVING ENERGY EFFICIENCY." Water Science and Technology 30, no. 4 (August 1, 1994): 17–23. http://dx.doi.org/10.2166/wst.1994.0149.
Full textAbstract:
The province of Ontario is Canada's most populous province with over 8 million residents out of a total population of 27 million. The Province is situated in the eastern portion of North America and stretches from 41°N to 50° N. All the Great Lakes fall within Ontario's boundaries and the Province is estimated to have over 280,000 lakes. The area along Lake Ontario is home to 5 million of the residents who are serviced by 11 large sewage treatment plants. The remaining 403 treatment plants are scattered throughout the province. with an average size of 20 000 m3/d. Ontario Hydro commissioned a study of the wastewater treatment plants to identify the main power users at the various types of sewage treatment plants, as well as potential areas within each plant where significant energy savings could be generated. By using this information, Ontario Hydro hoped to assess the potential to reduce the load and identify any electrical efficiency improvements, fuel switching and load shifting opportunities that may exist as well as the impact of environmental regulations on power saving initiatives. It was found that several major opportunities existed. These included:■ that up to 25% of power currently used can be reduced by introducing energy efficient measures■ of all the unit operations in wastewater treatment plants, aeration accounts for 42% of the power usage, influent and effluent pumping - 20%, and dewatering - 6%. Of this influent and effluent pumping, specifically influent represented the best target area as significant aeration system upgrade had already taken place.
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Malley, D. F., P. C. Williams, M. P. Stainton, and B. W. Hauser. "Application of Near-Infrared Reflectance Spectroscopy in the Measurement of Carbon, Nitrogen, and Phosphorus in Seston from Oligotrophic Lakes." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 8 (August 1, 1993): 1779–85. http://dx.doi.org/10.1139/f93-199.
Full textAbstract:
The application of near-infrared spectroscopy (NIRS), widely used in the agricultural, food, and pharmaceutical industries, is extended to the measurement of C, N, and P in seston from oligotrophic lakes at the Experimental Lakes Area, northwestern Ontario. Seston from 150-mL aliquots of lake water from several depths in two lakes on one mid-June sampling date was collected on Whatman GF/C filters and measured first by NIRS then analyzed by standard wet chemistry methods. Correlation between chemically measured and NIRS-predicted values gave coefficients of determination between 0.913 and 0.982. The rapid, low-cost, nonchemical, nondestructive, efficient analysis of C, N, and P in seston by NIRS is feasible.
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Welch, Harold E., John A. Legauit, and Hedy J. Kling. "Phytoplankton, Nutrients, and Primary Production in Fertilized and Natural Lakes at Saqvaqjuac, N.W.T." Canadian Journal of Fisheries and Aquatic Sciences 46, no. 1 (January 1, 1989): 90–107. http://dx.doi.org/10.1139/f89-013.
Full textAbstract:
Whole-lake phosphorus (P) and nitrogen (N) addition experiments at Saqvaqjuac, N.W.T. (63°N in the central Canadian arctic), showed that the lakes were P limited but required both P and N for increased production. Photosynthetic response to 0.1 g P and 1.0 g N∙m−2∙yr−1 was immediate (15→30 g C∙m−2∙yr−1), with simultaneous increases in protozoa, while oligotrophic chrysophyte assemblages gave way to volvocalean greens. Cyanophytes were not important during P-only or P and N additions or in oligotrophic lakes, but formed permanent blooms in several naturally mesotrophic lakes near sea level. Retention of P was naturally low, but high during P addition. Silicon (Si) retention was always very high. Chlorophyll: P ratios were similar to those of subarctic and north-temperate lakes. Saturation light intensity (Ik) tracked surface light flux with a 2- to 3-wk delay, averaging 15 E∙m−2∙s−1 in winter and peaking at 140 E∙m−2∙s−1 in July. Comparison of our data with those for lakes in the Experimental Lakes Area (northwestern Ontario, 50°N) and Char Lake (75°N) shows that with increasing latitude, in small lakes, (a) phytoplankton production decreases, (b) phytoplankton production per unit light decreases less sharply, and (c) the proportion of primary production occurring beneath ice cover increases.
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Foster, Neil W., Ian K. Morrison, and H. S. D. Swan. "Growth Response of a Boreal Black Spruce Stand to Fertilizer Treatments." Northern Journal of Applied Forestry 3, no. 4 (December 1, 1986): 142–44. http://dx.doi.org/10.1093/njaf/3.4.142.
Full textAbstract:
Abstract Results are reported for a fertilizer field trial with nitrogen (N), phosphorus (P), and potassium (K) fertilizers in a 100-yr-old black spruce stand in the Lake Nipigon region of northern Ontario. A comparison of four levels of N (0, 112, 224, and 336 kg/ha) revealed significant effects (p = .05) of treatment on diameter growth. In a comparison of N (112 and 224 kg/ha) in combination with K and PK (74 and 93 kg/ha, respectively) the volume growth of fertilized trees, at the end of 5 and 10 years, was generally greater than that of controls, but not significantly greater (p = .05). The best 10- year growth response was to 224 kg N/ha, which produced 7.4 m3/ha of extra wood over controls. No additional growth was realized when K and PK were added with N. North. J. Appl. For. 3:142-144, Dec. 1986.
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Samarasin, Pasan, Charles K. Minns, Brian J. Shuter, William M. Tonn, and Michael D. Rennie. "Fish diversity and biomass in northern Canadian lakes: northern lakes are more diverse and have greater biomass than expected based on species–energy theory." Canadian Journal of Fisheries and Aquatic Sciences 72, no. 2 (February 2015): 226–37. http://dx.doi.org/10.1139/cjfas-2014-0104.
Full textAbstract:
Biodiversity in northern Canada (north of 60°N latitude) is threatened, primarily by increasing resource exploitation and by climate change. Unfortunately, we have relatively limited knowledge of aquatic biodiversity for this region, making it difficult to develop suitable policies to manage these threats. Here we describe, quantify, and test hypotheses related to fish biodiversity and biomass in 37 lakes in a diamond mining district (the Barrenlands) in the Northwest Territories, Canada (64°N, 110°W). To estimate species richness and biomass of fish, we took advantage of exhaustive sampling and monitoring surveys conducted in the region and compared our northern estimates against estimates from southern Canadian lakes. We found that most of the 37 northern lakes contained two to four species, with the largest lake containing eight species. Salmonids dominated this system, with lake trout (Salvelinus namaycush) being the dominant species in abundance and biomass. Comparative analysis with similar-sized southern Canadian lakes showed no significant difference in the slopes of species richness versus lake area curves. Surprisingly, total fish biomass distributions for northern, Barrenlands lakes were also similar to southern, Ontario lakes. Overall, our results suggest that Barrenlands lakes are important natural resources of Canada that should be conserved for the future. Under anticipated scenarios of climate change, these lakes may represent important refugia for coldwater fishes (e.g., lake trout) as habitats at the southern edges of their ranges become more limiting.
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Lom, Jiří, Sherwin S. Desser, and Iva Dyková. "Some little-known and new protozoan parasites of fish from Lake Sasajewun, Algonquin Park, Ontario." Canadian Journal of Zoology 67, no. 6 (June 1, 1989): 1372–79. http://dx.doi.org/10.1139/z89-195.
Full textAbstract:
One hundred and twenty-six fish of eight species, taken from Lake Sasajewun, Ontario, were examined for protozoan parasites. Detailed descriptions are given for Sphaerospora diminuta Li and Desser from the pumpkinseed, Lepomis gibbosus, and for Goussia degiustii Molnar and Fernando from the common shiner, Notropis cornutus. Oocysts of G. degiustii are pleomorphic and exhibit low tissue specificity. Goussia freemani Molnar and Fernando from the kidney of N. cornutus is tentatively synonymized with Goussia leucisci Shulman and Zaika. Two new species of Sphaerospora are described: Sphaerospora paulini n.sp. from the renal tubules of creek chub, Semotilus atromaculatus, with spherical spores 8.1 (8.0–8.5) μm in diameter, containing ovoid polar capsules 2.8 (2.5–3.4) × 2.6 (2.5–3.0) μm, and polar filament with 4–5 coils; and Sphaerospora hankai n.sp. from the renal tubules of the brown bullhead, Ictalurus nebulosus, with subspherical spores 6.1 (5.4–6.6) × 6.0 (5.4–6.5) μm, unequal subspherical polar capsules (larger, 2.8 (2.5–3.1) × 2.7 (2.3–2.9) μm; smaller, 2.4 (2.1–2.6) × 2.0 (1.9–2.2) μm), and polar filament with 4–5 coils in larger capsule, 3–4 coils in smaller capsule. Eimeria patersoni n.sp. is described from the kidney, spleen, and liver of L. gibbosus. Oocysts are subspherical (11.9 × 10.6), sporocysts ellipsoidal (10.4 (9.9–11.2) × 3.5 (2.6–4.0) μm), and sporozoites stubby (3.6 × 2.0 μm); sporocyst residuum has 1–3 large granules.
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Eady, Allison, Bianca Dreyer, Brandon Hey, Manuel Riemer, and Anne Wilson. "Réduire les risques de chaleur extrême pour les personnes âgées : communiquer les risques et renforcer la résilience." Promotion de la santé et prévention des maladies chroniques au Canada 40, no. 7/8 (July 2020): 239–50. http://dx.doi.org/10.24095/hpcdp.40.7/8.01f.
Full textAbstract:
Introduction Les changements climatiques mondiaux entraînent des vagues de chaleur qui ont une incidence disproportionnée sur les personnes âgées et divers autres groupes socialement vulnérables. Afin d’atténuer les risques associés aux épisodes de chaleur extrême, il est essentiel d’élaborer et de promouvoir des ressources permettant de faire face à ces épisodes. Une meilleure compréhension du rôle de la perception des risques et des facteurs qui les influencent permettra d’améliorer les réactions du public aux événements menaçants, en particulier chez les personnes âgées. Méthodologie Cette étude à méthodologie mixte visait à examiner la perception des risques et les pratiques d’adaptation des personnes âgées en effectuant des entrevues qualitatives (n = 15) et une enquête (n = 244) auprès de personnes âgées de la région de Waterloo (Ontario). Résultats Les personnes âgées ont fait preuve d’une connaissance relativement précise des risques, comme l’indique le lien entre les mesures du risque réel et la perception de leur risque personnel. Alors que l’on associe souvent la vulnérabilité à la chaleur à une perception inexacte du risque, dans notre échantillon, cette vulnérabilité semble plus fortement liée à la situation sociale et à l’accès aux ressources. Les participants ont cité les liens sociaux comme des ressources importantes pour la résilience et ont mentionné la stigmatisation entourant la vulnérabilité ainsi que d’autres normes sociales comme des obstacles à la recherche de soutien. Conclusion L’une de nos constatations importantes est la relation positive entre la perception des risques par les participants et le risque réel de subir les conséquences négatives d’une chaleur extrême, alors que les problèmes de préparation aux situations d’urgence et de réduction des risques sont souvent présentés comme des questions de sensibilisation aux risques plutôt que de situation sociale et d’inégalité. Outre l’augmentation des ressources publiques pour composer avec la chaleur extrême, la communication sur les ressources, la promotion des liens sociaux et la réduction de la stigmatisation peuvent s’avérer des aspects cruciaux dans l’augmentation de la résilience des personnes âgées face aux vagues de chaleur.
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Findlay, David L., Cheryl L. Podemski, and Susan E. M. Kasian. "Aquaculture impacts on the algal and bacterial communities in a small boreal forest lakeThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 11 (November 2009): 1936–48. http://dx.doi.org/10.1139/f09-121.
Full textAbstract:
A whole-lake experiment to examine the impacts of aquaculture on a freshwater ecosystem was conducted at the Experimental Lakes Area in northwestern Ontario, Canada. From 2003 to 2006, a 10 tonne fish capacity aquaculture cage stocked with rainbow trout ( Oncorhynchus mykiss ) was operated in Lake 375 and the impact of excess nutrients on the algal and bacteria communities was examined. The experiment was designed as a nutrient loading experiment with fish food and fish excretion the source of nutrients. Total N and P concentrations increased over the 4 years (15× and 4×, respectively). Phytoplankton biomass increased 4× annually following the start of aquaculture operation in 2003. The most dramatic responses occurred during spring and fall mixing, with blooms of chrysophytes and dinoflagellates increasing biomass by up to 12×. Bacteria biomass and densities were unaffected except for increases in late fall. Periphyton biomass was relatively unaffected except for an increase in biomass in the fourth year. The combination of a long water residence time in the lake coupled with an extremely high fish stocking density in Lake 375 resulted in an immediate impact on water quality. The results suggest that the impacts of aquaculture are accumulative and continual stocking will further impact water quality.
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Craigie, G. Eoin, and Scott A. Petrie. "Moult intensity and chronology of Tundra Swans during spring and fall migration at Long Point, Lake Erie, Ontario." Canadian Journal of Zoology 81, no. 6 (June 1, 2003): 1057–62. http://dx.doi.org/10.1139/z03-089.
Full textAbstract:
Moult intensity and chronology in staging Eastern-Population (EP) Tundra Swans (Cygnus columbianus columbianus) were studied during spring in 1999 and 2000 (n = 35) and during fall in 1999, 2000, and 2001 (n = 47) at Long Point, Lake Erie, Ontario. To test for age, sex, and seasonal differences in moult intensity, 20 feather regions were scored according to the proportion of growing feathers. Adult, subadult, and juvenile Tundra Swans moulted contour feathers at low intensities during spring and fall. Males and females of all three age classes had similar patterns and intensities of moult during spring and fall. Shared costs of incubation and brood rearing, perennial monogamy, and lack of a breeding plumage could be some of the pressures selecting for intersexual similarities in feather replacement during migration. Adult, subadult, and juvenile Tundra Swans moulted more intensively during fall than spring. Larger lipid reserves and seasonal dietary differences may allow fall-staging Tundra Swans to moult more intensively than spring-staging birds at Long Point. Overlap of nutritionally costly events (moult and migration) may be necessary as Tundra Swans spend half of their annual cycle on spring and fall staging areas. However, reduced daily nutritional costs associated with moulting at low intensities and migrating slowly apparently permits the overlap of these two life-cycle events.
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Johannsson, Ora E., Mike F. Leggett, Lars G. Rudstam, Mark R. Servos, M. Ali Mohammadian, Gideon Gal, Ron M. Dermott, and Ray H. Hesslein. "Diet of Mysis relicta in Lake Ontario as revealed by stable isotope and gut content analysis." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 10 (October 1, 2001): 1975–86. http://dx.doi.org/10.1139/f01-118.
Full textAbstract:
Stable isotope analysis of the potential prey and predator can be combined with gut content analysis to quantify the diet. This dietary knowledge allows the quantitative assessment of the role of key species in energy and contaminant transfer, their impact on prey communities, and their susceptibility to perturbation. The diet of Mysis relicta was examined in Lake Ontario in spring, summer, and autumn using both techniques. Mysids fed on the bottom during the day and in the pelagia and on the bottom at night. A trophic fractionation of 2.2 N between mysids and their prey provided the best correspondence between the observed stable isotope signature of mysids and that estimated from their diet. Tissue turnover rate of δ13C was slow compared with that of δ15N. Diatoms formed 50% of the assimilated diet in May. In September, 25% of large mysids feeding on the bottom contained amphipod parts and 20% contained phytoplankton. The remainder of the diet consisted of zooplankton and rotifers. The contribution of amphipods and phytoplankton could not be quantified. Revised daily consumption estimates, based on this new diet information and clearance rate estimates of consumption, gave daily consumption estimates similar to those estimated from previous bioenergetic modelling.
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Blades, David C. A., and Stephen A. Marshall. "TERRESTRIAL ARTHROPODS OF CANADIAN PEATLANDS: SYNOPSIS OF PAN TRAP COLLECTIONS AT FOUR SOUTHERN ONTARIO PEATLANDS." Memoirs of the Entomological Society of Canada 126, S169 (1994): 221–84. http://dx.doi.org/10.4039/entm126169221-1.
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AbstractThis report is a synopsis of the terrestrial arthropod faunas collected from four peatlands in southern Ontario. The peatlands surveyed were the Wylde Lake bog (43°55′N, 80°30′W), Crieff fen (43°25′N, 80°07′W), Oliver bog (43°20′N, 80°16′W), and the Wainfleet bog (42°55′N, 79°17′W). Arthropods were collected in yellow pan traps (aluminum pan traps at Wainfleet) during the period May 1987 to June 1988 (including the period of snow cover from December to March). A total of 33 029 specimens were removed from the pan trap samples and of these 17 173 individuals were assigned to species. Between 603 and 870 species of arthropods were identified from each site. Collections from each site were compared using taxonomic and ecological groupings (based on feeding behaviour and habitat preference) of species. Sorensen's Index of Similarity was used to compare the overlap of species among sites. The Hymenoptera, Diptera, Coleoptera, and Araneae were the most species-rich orders collected at each site. More species preferring peatlands were collected at each of the three undisturbed peatlands (Wylde L., Crieff, and Oliver) than at the mined bog, Wainfleet. Species not usually associated with peatlands were more numerous in the Wainfleet collection than in collections from the undisturbed sites. It is concluded that grouping of species by habitat preference is a useful technique for assessing habitat disturbance.
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Herborg, Leif-Matthias, Nicholas E. Mandrak, Becky C. Cudmore, and Hugh J. MacIsaac. "Comparative distribution and invasion risk of snakehead (Channidae) and Asian carp (Cyprinidae) species in North America." Canadian Journal of Fisheries and Aquatic Sciences 64, no. 12 (December 1, 2007): 1723–35. http://dx.doi.org/10.1139/f07-130.
Full textAbstract:
As nonindigenous species are a major threat to global biodiversity, cost-effective management requires identification of areas at high risk of establishment. Here we predict suitable environments of 14 high-profile species of nonindigenous snakehead (Channidae) and Asian carp (Cyprinidae) species in North America based upon ecological niche modelling and compare the driving environmental variables for the two fish groups. Snakeheads distributions were correlated with thermal factors, whereas those of Asian carps were related mainly to precipitation. Predicted suitable ranges for these nonindigenous species can be divided into three main areas: Mexico and the southern United States (five species); Mexico and the United States up to ~35 °N (three species); and most of Mexico, continuous United States, and southern Canada (six species). For the province of Ontario, we combined the number and location of aquarium stores and live fish markets with predicted areas of suitable environments to identify areas at risk of introduction and establishment. We identified several watersheds draining into northwestern Lake Ontario as having the highest risk, highlighting the increased predictive value of this approach.