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Biodiversity in Canadian Lakes and Rivers

Synthesis of Data

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Biodiversity is a notoriously complex and often poorly defined concept. Reporting on biodiversity patterns by simply amassing existing data on the occurrence of species and habitats across Canada will quickly run into problems of data comparability. For example, combining single species surveys (such as from fisheries stock assessment or endangered species plans) into distribution maps may seem to yield consistent information, until one realises that how, when, and where observations were made is likely to vary considerably depending on the study. When collating data in this way, apparent species 'absences' are open to a variety of interpretations. Such problems are compounded when site-collected species data are combined to examine patterns of faunal richness at larger geographical scales. For scientifically sound interpretation of biodiversity patterns, therefore, data should ideally be collected using a consistent methodology. Of course, this is often impossible to achieve when combining historical data, and extremely difficult in new multi-partner initiatives, as methods standardization is a highly contentious issue with significant transaction costs. A possible solution to this problem is the development of metadata approaches, which permit data to be shared within a network, even when collected using a diversity of methods. Here the metadata can form the basis of a screening tool to extract data with common properties for specific reporting purposes, while still permitting data to be shared among a diversity of partners.

Table 10, Table 11, and Table 12 summarize the important trends in lakes and rivers in Canada derived from data analyses, literature analyses, and published scientific studies nationally and for each ecozone+. One of the major conclusions that can be drawn from this analysis is a general lack of consistently collected, longer-term data sets. Despite recently developed national biomonitoring strategies (for example, see Canadian Aquatic Biomonitoring Network in Environment Canada, 2009a), records for biological community monitoring are limited. Our knowledge of the biodiversity within Canada's freshwater ecosystems is highly fragmented, with much valuable information currently inaccessible for monitoring and reporting purposes. While some aspects of biodiversity, notably habitat diversity, are being captured by ongoing initiatives, such as the Nature Conservancy of Canada's freshwater habitat mapping studies (Ciruna et al., 2007), others remain lost in an institutional hinterland of fragmented and neglected data archipelagos. To improve our ability to work with this untapped resource of currently unavailable data, there is an urgent need for improved, strategic efforts in the area of ecoinformatics. Linking up existing on-line data sources through improved data discovery tools, and making currently off-line data available is an important first step in understanding national-level patterns in aquatic biodiversity, and how these have been changing in recent years.

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Table 10. Summary of national trends from this analysis, literature analysis, and previous published scientific research.
Trends derived for data from 1970 to 2005
VariableTrend description
Magnitude of monthly conditionsFew trends apparent. Strong ↑ in April runoff and ↓ trend for May to August runoff
Magnitude of runoff-minimumMajority ↔ esp. longer duration. ~ quarter of sites ↓
Magnitude of runoff-maximumMajority ↔ but large number of sites showing tendency towards ↘ esp. long duration
Timing of annual minimumFew sites with significant trends
Nearly half of sites showing tendency towards ↗ (later) annual minimum
Timing of annual maximumFew sites with significant trends. Majority of sites showing tendency towards ↘ (earlier) annual maximum
Frequency of extreme low flow eventsMajority of sites ↔
Frequency of extreme high flow eventsMajority of sites ↔
Duration of extreme eventsMajority of sites ↔  Slight trend towards ↓ trend in duration of low pulse events.
Flashiness of eventsFew sites with significant trends for rise rate and fall rate. Tendency towards ↗ in fall rate ↘ and in rise rate for nearly half of sites. ↑ number of reversals for third of sites.
Ice freeze-upIceWatch (2008) report suggests little evidence for changes in ice freeze-up.
Analysis for this report shows sites reflects this result.
Ice break-upIceWatch (2008) report showed 40 of the 285 sites showed significantly (p<0.05) earlier spring melt (with an additional 168 sites showing a non-significant (p>0.05) earlier tendency)
Analysis for this report demonstrated 8 out of 69 sites showed a significantly (p<;0.05) earlier spring melt (with an additional 46 sites demonstrating a non-significant (p>0.05) earlier tendency)
Habitat connectivityPeak number of dams >10m in height (57) completed in 1971.
Earliest large dam completed in 1830.
Majority of dams completed between 1950 and 1990 with recent decline.
Interbasin transfers and diversions (mainly for hydropower) have altered hydrological regimes, particularly in SK, QC, ON, and NL.
Trends in land use changes have caused shifts in hydrological regimes, e.g., Lower Fraser Basin
ContaminantsFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south
NutrientsGlozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems
AcidificationAcidic deposition in eastern Canada has reduced since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Table 10 Reference:
↑ = significant increase (p<0.1); ↗ tendency towards increase (p>0.1); ↓ = significant decrease (p<0.1); ↘ = tendency towards decrease (p>0.1); N.D. = not enough available data

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Table 11. Summary of hydrological trends by ecozone+, 1970–2005.
Ecozone+Magnitude of monthly conditionsMagnitude of runoff-minimumMagnitude of runoff-maximumTiming of annual minimumTiming of annual maximumFrequency of extreme low flow eventsFrequency of extreme high flow eventsDuration of extreme eventsFlashiness of events
ArcticN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Atlantic MaritimeStrong ↓ for late spring and summer runoffTendency towards ↘Tendency towards ↗ (later) minimumTendency towards ↘ (earlier) maximumTendency towards ↘Tendency towards ↘ rise rate and ↗ fall rate; ↔ in reversals
Boreal CordilleraN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Boreal PlainsN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Boreal ShieldFew sites with trends↓ and ↘ (except longer duration ↔)↓ and ↘↗ in southern area; ↘ across area + western area↘ across area; ↗ in central + western areaTendency towards ↘Tendency towards ↗ in extreme low + high flow eventsTendency towards ↘ rise rate, ↗ in fall rate; ↔ reversals
Hudson PlainsN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Mixedwood PlainsN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Montane CordilleraFew clear trends but strong ↑for April runoffTendency towards ↘Tendency towards ↘(earlier) maximumTendency towards ↗Tendency towards ↗ rise rate; ↔ fall rate; ↑ in reversals
Newfoundland BorealNo clear trend. Slight ↓ for August↓ and ↘Trend towards ↗ (later) minimumTrend towards ↗ (later) maximum
Pacific Maritime↓ trend in late spring and summer runoff↓and ↘↑ and ↗Tendency towards ↗ (later) minimumTrend towards ↘ (earlier) maximumTendency towards ↗Tendency towards
PrairieN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Taiga CordilleraN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Taiga Plain↑ trend in winter and early spring runoff↔for rise rate and fall rate; ↑ reversals
Taiga ShieldN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Western Interior BasinN.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.N.D.
Table 11 Reference:
↑ = significant increase (p<0.1); ↗ tendency towards increase (p>0.1); ↓ = significant decrease (p<0.1); ↘ = tendency towards decrease (p>0.1); ↔ = split between increasing and decreasing trends; N.D. = not enough available data

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Table 12. Summary of trends from this analysis, literature analysis, and previous published scientific research by ecozone+.
Ecozone+Ice freeze-up (using evidence from
Table 7)
Ice break-up (using evidence from
Table 8
Habitat connectivity (using data from Canadian Dam Association)ContaminantsNutrientsAcidification
ArcticN.D.Trend towards earlier break-up (c)No dams recordedFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Atlantic MaritimeEarlier (a)Later (b); No clear trend (a)74 dams, development throughout 20th centuryFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Boreal CordilleraEarlier (a)Earlier (a, b and c)4 dams, built between 1950 and 1970Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Boreal PlainsMixed trend (c)Trend towards earlier break-up (c)14 dams, built between 1950–1990Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Boreal ShieldN.D.N.D.265 dams, development throughout 20th century
42% built between 1950–1980
Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Hudson PlainsN.D.N.D.13 dams, built between 1960 and 1990
10 of 13 built between 1970–1980
Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Mixedwood PlainsMixed trend (c)Later (b); Mixed trend (c)67 dams, development throughout 20th centuryFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Montane CordilleraMixed trend (c)Trend towards earlier break-up (c)39 dams, development throughout 20th centuryFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Newfoundland BorealEarlier trend (c)Trend towards earlier break-up (c)39 dams, development throughout 20th century with 38% built between 1980–1990Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Pacific MaritimeN.D.N.D.47 dams, development throughout 20th centuryFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
PrairieMixed trend (c)Earlier (a and b); Mixed trend (c)83 dams, majority (64%) built between 1950 and 1970Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Taiga CordilleraN.D.N.D.No dams reportedFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Taiga PlainN.D.N.D.1 dam, built in 1989Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Taiga ShieldTrend towards later freeze-up (c)Trend towards earlier break-up (c)177 dams
Majority (88%) built between 1970 and 1990
Few long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.
Western Interior BasinN.D.N.D.19 dams, development throughout 20th centuryFew long-term trends information outside the Great Lakes region. Studies in the Arctic indicate continued concerns with rising POP levels from pollutants transported from the industrialised south.Glozier et al. (2009 - draft report) provide a national summary of long-term (1990–2006) trends in nitrogen and phosphorous in aquatic systems.Acidic deposition in eastern Canada has decreased since the 1970s and pH levels in lakes affected in these regions are recovering. However, there is little evidence of any biological recovery in many affected lakes.

Sources: (a) 1957–1996: Zhang et al. (2001); (b) 1960–1997: Burn and Hag Elnur (2002); (c) 1961–1990: Duguay et al. (2006)

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