9 results
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2. How different is different? Defining management and conservation units for a problematic exploited species.
- Author
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Bernard, Andrea M., Ferguson, Moira M., Noakes, David L.G., Morrison, Bruce J., and Wilson, Chris C.
- Subjects
LAKE whitefish ,MICROSATELLITE repeats ,SPAWNING ,CANADA. Committee on the Status of Endangered Wildlife ,FISH conservation ,FISHERY management - Abstract
Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2009
- Full Text
- View/download PDF
3. Limnology in northeastern Ontario: from acidification to multiple stressors.
- Author
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^Keller, W.
- Subjects
LIMNOLOGY ,ACIDIFICATION ,ATMOSPHERIC sulfur compounds ,EMISSIONS (Air pollution) ,COASTAL organisms - Abstract
Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2009
- Full Text
- View/download PDF
4. Changes in phytoplankton communities following logging in the drainage basins of three boreal forest lakes in northwestern Ontario (Canada), 1991-2000.
- Author
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Nicholls, K.H., Steedman, R.J., and Carney, E.C.
- Subjects
PHYTOPLANKTON ,LAKES ,BIODIVERSITY ,LOGGING ,WATERSHEDS - Abstract
Focuses on changes in phytoplankton abundance, biodiversity and community structure in three small Precambrian Shield boreal forest lakes in northwestern Ontario for several years before and after experimental watershed and shoreline clearcut logging operations and associated forest regeneration practices. Possible effects of forest harvesting within drainage basins; Data analysis; Total phytoplankton biovolumes in the three lakes.
- Published
- 2003
- Full Text
- View/download PDF
5. Critical loads of acidity for surface waters in south-central Ontario, Canada: regional application of the Steady-State Water Chemistry (SSWC) model.
- Author
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Henriksen, A., Dillon, P.J., and Aherne, J.
- Subjects
ACID pollution of rivers, lakes, etc. ,SULFUR deposits - Abstract
Estimates critical loads of acidity and the amount by which these critical loads are exceeded by atmospheric deposition, for 1469 lakes from five regions in south-central Ontario, using single lake chemistry measurements and sulphur deposition data for the period 1976-1999. Reduction in the portion of lakes with critical load exceedances due to the declining sulphur deposition.
- Published
- 2002
- Full Text
- View/download PDF
6. Scaled chrysophytes as indicators of water quality changes since preindustrial times in the Muskoka-Haliburton region, Ontario, Canada.
- Author
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Paterson, Andrew M., Cumming, Brian F., Smol, John P., and Hall, Roland I.
- Subjects
CHRYSOPHYCEAE ,SEDIMENTS ,WATER quality - Abstract
Examines the scaled chrysophytes preserved in modern and fossil sediment samples from lakes in Ontario. Evaluation of the changes in water quality; Determination of chrysophyte distributions using redundancy analysis; Introduction of a multi-indicator reconstruction model.
- Published
- 2001
- Full Text
- View/download PDF
7. Diet of Mysis relicta in Lake Ontario as revealed by stable isotope and gut content analysis.
- Author
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Johannsson, Ora E, Leggett, Mike F, Rudstam, Lars G, Servos, Mark R, Mohammadian, M Ali, Gal, Gideon, Dermott, Ron M, and Hesslein, Ray H
- Subjects
MYSIS relicta ,LAKES ,AQUATIC animals ,AQUATIC biology - Abstract
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 δ[sup 13] C was slow compared with that of δ[sup 15] N. 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.L'analyse des isotopes stables chez les proies et les prédateurs potentiels combinée à l'examen des contenus du tube digestif permet de quantifier le régime alimentaire. Cette information rend possible l'évaluation quantitative du rôle des espèces-clés dans le transfert de l'énergie et des contaminants, de leur impact sur les communautés de proies et de leur vulnérabilité aux perturbations. Le régime alimentaire de Mysis relicta au lac Ontario au printemps, à l'été et en automne a été analysé à l'aide de ces deux techniques. Le jour, les Mysis se nourrissent sur le fond, mais la nuit ils s'alimentent à la fois dans les zones pélagique et profonde. Un fractionnement trophique de 2,2‰ de l'azote entre les Mysis et leurs proies donne la correspondance optimale entre la signature d'isotopes stables observée chez les Mysis et celle estimée à partir de leur régime alimentaire. Le taux de renouvellement tissulaire du δ[sup 13] C est faible par comparaison à celui du δ[sup 15] C. Les diatomées constituent 50% de la nourriture assimilée en mai. En septembre, 25% des Mysis de grande taille à alimentation benthique ont des restes d'amphipodes dans leur tube digestif et 20% ont du phytoplancton. Le reste du régime alimentaire est composé de zooplancton et de rotifères. L'apport des amphipodes et du phytoplancton n'a pu être quantifié. Les taux révisés de consommation journalière, basés sur ces informations nouvelles et sur des estimations du taux de clearance de la consommation, donnent des estimations de consommation journalière semblables à celles obtenues à l'aide des modèles bioénergétiques antérieurs.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
8. Calcium declines in northeastern Ontario lakes.
- Author
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Keller, W, Dixit, S S, and Heneberry, J
- Subjects
LAKES ,CALCIUM ,WATER quality ,AQUATIC ecology - Abstract
Thousands of lakes in northeastern Ontario, Canada, have been acidified by sulphur deposition associated with emissions from the Sudbury area metal smelters. However, water quality improvements including increased pH and reduced sulphate concentrations have followed large reductions in Sudbury emissions that were implemented, beginning in the 1970s. Substantial decreases in Ca concentrations accompanied these other changes in lakewater chemistry. Monitoring of 38 lakes 20–128 km from Sudbury showed declines in Ca concentrations, averaging 2.7 µeq·L[sup –1] ·year[sup –1] , over the period 1981–1999. Declines were particularly apparent during the 1990s, averaging 3.8 µeq·L[sup –1] ·year[sup –1] . Paleolimnological reconstructions of the long-term Ca patterns in six lakes suggest that general lakewater Ca declines occurred through much of the 20th century. Comparison of recent measured Ca concentrations in 16 lakes with diatom-inferred pre-industrial Ca concentrations indicates that overall decreases in Ca have been large, averaging 74.6 µeq·L[sup –1] or 46%. Long-term Ca patterns may reflect a combination of factors including climatic changes, forest harvesting activities, and leaching by acid deposition, the effects of which we can not separate. Calcium declines have biological implications that will need to be considered in the development of appropriate targets as these lakes continue to recover from acidification.Des milliers de lacs du nord-est de l'Ontario, Canada, ont été acidifiés par les dépôts de soufre provenant des émissions des fonderies de la région de Sudbury. Cependant, les réductions importantes des émissions depuis les années 1970 ont entraîné une amélioration de la qualité de l'eau et, en particulier, un accroissement du pH et une diminution des concentrations de sulfates. Des réductions importantes des concentrations de Ca ont accompagné ces changements dans la chimie des eaux des lacs. Le suivi de 28 lacs situés à des distances de 20 à 128 km de Sudbury indique des déclins dans les concentrations de Ca d'en moyenne 2,7 µeq·L[sup –1] ·année[sup –1] de 1981 à 1999, particulièrement durant les années 1990 où les taux étaient en moyenne de 3,8 µeq·L[sup –1] ·année[sup –1] . Des reconstitutions paléolimnologiques de l'évolution à long terme du Ca dans six des lacs laissent croire que le déclin général du Ca dans l'eau des lacs s'est poursuivi pendant presque tout le vingtième siècle. Une comparaison des concentrations récentes de Ca dans 16 lacs avec les concentrations estimées d'après les peuplements de diatomées avant l'ère industrielle montre que le déclin de Ca a été important, en moyenne de l'ordre de 74,6 µeq·L[sup –1] ou de 46%. Cette évolution à long terme du Ca peut être le reflet d'une combinaison de facteurs, dont les effets ne peuvent être séparés, en particulier les changements climatiques, les activités de coupe des forêts et le lessivage dû aux précipitations acides. Les déclins du Ca ont des implications biologiques qu'il sera nécessaire de considérer dans la définition d'objectifs appropriés, à mesure que ces lacs se rétablissent de l'acidification.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
9. Application of fuzzy cluster analysis to Lake Simcoe crustacean zooplankton community structure.
- Author
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Nicholls, Kenneth H. and Tudorancea, Claudiu
- Subjects
FUZZY sets ,CRUSTACEA ,ZOOPLANKTON - Abstract
Proposes the use of fuzzy cluster membership weights for ranking species important in a classification of the sampling unit, using crustacean-zooplankton data from Lake Simcoe in Ontario. Identification of elements of interannual and spatial variability in the crustacean zooplankton; Other aspects of crustacean zooplankton community structure.
- Published
- 2001
- Full Text
- View/download PDF
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