Skip booklet index and go to page content

Atlantic Maritime Ecozone evidence for key findings summary

Theme: Biomes

Key finding 1
Forests

Theme Biomes

National key finding
At a national level, the extent of forests has changed little since 1990; at a regional level, loss of forest extent is significant in some places. The structure of some Canadian forests, including species composition, age classes, and size of intact patches of forest, has changed over longer time frames.

Forest is the predominant land cover in the AME, although total estimates have varied depending on the methods used. Using a mix of remote and ground-based sampling, the Canadian National Forest Inventory found that forests comprised approximately 77% of the area of the AME in 2001, consisting of 44% coniferous, 33% mixed, and 21% broadleaf forest.Footnote10 Based on 2005 remote sensing data, Ahern et al.Footnote7 estimated forest cover at over 85%. Differences between the two estimates reflect different methodologies and definitions of forest rather than a change in the area of forest in the AMEFootnoteiii.

Land clearing for agriculture and urban areas reduced the extent of post-settlement forests in certain areas, yet the AME remains well forested overall. By the beginning of the 20th century, 70% of the forest had been cleared for agriculture in PEI.Footnote14 Agricultural land also replaced forest in much of Nova Scotia’s Annapolis and New Brunswick’s Saint John river valleys. However, Ahern et al.7 found no significant change in the extent of forest cover between 1985 and 2005 based on remote sensing data. An analysis of forest density found that, other than in the Annapolis River Valley, the Saint John River Valley, and on most of Prince Edward Island, forest density was high for most of the AME. Over 30% of the 1 km2 cells within the AME were more than 90% forested and another 20% were more than 80% forested.Footnote7

Age class distribution and composition of forests have changed through time, however, drawing general conclusions for the AME as a whole was difficult because there were no long-term data sets that covered the entire ecozone+. In general, the successional stage and age distribution of the forest shifted from old-growth to younger age classes.Footnote15 Over the past several decades, forests have also become simplified in species and ecosystem diversity as a result of forest clearing and regrowth and natural disturbances.Footnote16

For more than 300 years the economy of the region has been dependent on forests to supply a diversity of products and services.Footnote17

There are three forest regions in the AME (Figure 4):Footnote18

  1. The Acadian Forest Region, which extends into the northeastern United States, includes all of Nova Scotia and Prince Edward Island, and all but the northwestern corner of New Brunswick. It occupies an area of 122,000 km2, is entirely within the AME in Canada, and represents 44% of the area of the AME.Footnote19, Footnote20 The region is transitional between the mostly deciduous forests of the south and west and the boreal coniferous forests of the north, and includes components of both.Footnote16
  2. The Great Lakes–St. Lawrence Forest Region is predominantly a closed, mixed coniferous-deciduous forest. It is strongly influenced by the warm summers of the maritime climate that allow hardwoods to thrive. The forest region extends inland from the Great Lakes and St. Lawrence River to southeastern Manitoba, excluding the area north of Lake Superior. In the AME, this region occupies the northeast corner of New Brunswick, part of the Gaspé Peninsula, and the southern shore of the St. Lawrence River.
  3. The Boreal Forest Region extends in a continuous belt from Newfoundland and Labrador west to the Rocky Mountains and north to Alaska. In the AME, it stretches from the northwestern tip of New Brunswick into the Gaspé Peninsula. This forest region is mostly coniferous, with black spruce (Picea mariana) and balsam fir (Abies balsamea) as principal species, but also includes some deciduous trees, such as white birch (Betula papyrifera) and trembling aspen (Populus tremuloides).

Quebec uses major bioclimate domains and subdomains to classify its forests and four of these include parts of the AME: sugar maple–basswood (east), sugar maple–yellow birch (east), balsam fir–yellow birch (east), and balsam fir–white birch (east) (Figure 5). These subdomains also include parts of the Boreal Shield and Mixedwood Plains ecozones+. Because the sugar maple--basswood (east) mostly includes land outside the AME, it is not included here. The Quebec forest subdomains in the AME overlap with the Great Lakes–St. Lawrence and Boreal forest regions defined above.

Figure 4. Forest regions and the principal tree species within each region.

map

Long Description for Figure 4

This map depicts the locations and boundaries of the three forest regions in the Atlantic Maritime Ecozone+ and lists the principal tree species within each region. The Acadian forest region covers Nova Scotia, Prince Edward Island, and most of New Brunswick with the exception of an area near the Quebec–New Brunswick border.  Principal tree species of the Acadian forest region are: red spruce, balsam fir, maple, and yellow birch.  The Great Lakes–St. Lawrence forest region covers the east coast of the Gaspé Peninsula, most of the east coast of the St. Lawrence River, and runs along the Canada–U.S. border.  Principal tree species of the Great Lakes–St. Lawrence forest region are: red pine, eastern white pine, eastern hemlock, yellow birch, maple, and oak.  Within the Atlantic Maritime Ecozone+, the Boreal forest region covers the northern Gaspé Peninsula with the exception of a strip along Chaleur Bay and a large patch inland of the St. Lawrence encompassing Edmondston, New Brunswick. Larger areas of this forest region are found west of the St. Lawrence River outside of the ecozone+. Principal tree species of the Boreal forest region are: white spruce, black spruce, balsam fir, jack pine, white birch, and trembling aspen.

Source: Natural Resources Canada, 2007Footnote21

Figure 5. Quebec forest domains.

map

Long Description for Figure 5

This map shows the distribution of major bioclimate domains and subdomains that the Province of Quebec uses to classify its forests. Four domains are included in the Atlantic Maritime Ecozone+: sugar maple–basswood (east), sugar maple–yellow birch (east), balsam fir–yellow birch (east), and balsam fir–white birch (east). The balsam fir–white birch (east) domain covers the inland area of the Gaspé Peninsula, and balsam fir–yellow birch (east) surrounds the coast of Gaspé and continues down the St. Lawrence River until just north of Québec City.  South of the balsam fir–yellow birch (east) domain is the sugar maple–yellow birch (east) domain which covers the remaining area of southern Quebec in the Atlantic Maritime Ecozone+, with the exception of a pocket of sugar maple–basswood (east) in the southwest corner of the ecozone+.

Source: Ministère des Ressources naturelles et Faune, 2005Footnote22

Top of Page

Forest age structure

It has been estimated that as much as 50% of the forest in the AME may have been dominated by late-successional, old-growth forest types before European settlement.Footnote15 In 2003, only about 1–5% of forests were estimated to be older than 100 years, and ground surveys suggest that far less than this had true old-growth forest characteristics.15 A high proportion of the forests fell within the young age classes in 1999 (Figure 6), reflecting re-growth after forest harvesting.10

Figure 6. Age-class distribution by forest type on stocked forest land as a percentage of the total stocked forest area in the Atlantic Maritime ecozone+, 1999.

graph

Long Description for Figure 6

This figure is a bar graph showing the age-class distribution by forest type (softwood, mixedwood, and hardwood) on stocked forest land as a percentage of the total stocked forest area in the Atlantic Maritime Ecozone+ in 1999. The graph shows that the forest distribution was skewed toward the younger forest classes in 1999 (<81 years old). For the three types of forest, over 40% of the forest falls in the 41–80 year-old age class.  The second highest percentage age class was the youngest forest in the 0–40 year-old age class which comprised over 20% of the total stocked forest area in all forest types.  Uneven-aged and the 81 – 120 year-old age class both comprised just over 10% of stocked forest land, while the 121–160 year old age class comprised less than 2.5%. The oldest age class, the 161+ age class, made up less than 1% of stocked forest. 

Source: adapted from Canadian Council of Forest Ministers, 200510

Acadian forest

Younger forests increased and older forests declined between 1958 and 2003 in Nova Scotia (Figure 7).Footnote23 The youngest age class (less than 20 years) increased as a proportion of total forest cover, from 3.8% in the early 1970s to 23.9% in the 1997–2003 inventory. Forests greater than 101 years of age decreased from 8.7% in 1958 to 0.3% in the 1997–2003 inventory and forests between 81 and 100 years decreased from 16.4 to 1.2%.

Figure 7. Percent of total forest area in each age class in Nova Scotia, 1958–2003.

graph

Long Description for Figure 7

This figure is a bar graph showing the following information:

Data for figure 7.
Years1958
(%)
1965-71
(%)
1970-78
(%)
1975-82
(%)
1976-85
(%)
1979-89
(%)
1999
(%)
1997-2003
(%)
<20 yrs 5.63.86.210.61216.323.9
21-40 yrs6.312.711.913162015.312.8
41-60 yrs34.540.135.134.936.440.336.332.3
61-80 yrs34.332.632.728.225.122.111.511.9
81-100 yrs16.477.58.353.411.2
>101 yrs8.70.91.11.90.70.60.20.3

Time periods are ranges and vary as Pannozza and Coleman (2008) compiled data from several sources: Forest Resources of Nova Scotia (1958); Nova Scotia Forest Inventory provincial summary (1965–1971, 1970–1978, 1975–1982, 1976–1985, 1979–1989); Department of Natural Resources GIS 1995 inventory data (1999); and Department of Natural Resources GIS unpublished inventory data (1997–2003).
Source: adapted from Pannozza and Coleman, 2008Footnote23

Forest subdomains in Quebec portion of AME

Trends from the 1970s to the 1990s showed a gain in balsam fir domain forest stands in a mature developmental stage (Figure 8). Within this 30-year period, 19% of the balsam fir–yellow birch forest sub-domain became mature, while 23% was lost from the young category.Footnote24 In the balsam fir–white birch sub-domain, mature forest stands and regenerated stands remained stable (2% increase and 1% decrease respectively) over the same time period, while young forest stands decreased by 5% and regenerating forest stands increased by 3%. For the sugar maple–yellow birch subdomain, young forest stands decreased by 3% and regenerated stands increased by 6%.24 Over the 30-year period, the proportion of mature stands did not change. These data included areas outside the AME.

Figure 8. Proportion of forest at each major developmental stage in Quebec’s subdomains that occur in the Atlantic Maritime ecozone+, 1970s, 1980s, and 1990s.

graph

Long Description for Figure 8

This figure has three bar graphs that show the following information:

Data for figure 8

Balsam fir – yellow birch (east)
TypePercent of total forest
1970-79
Percent of total forest
1980-89
Percent of total forest
1991-99
Mature29.0142.2748.30
Young50.1634.0627.29
Regenerated13.1614.3019.33
Regenerating7.679.375.07
Balsam fir – white birch (east)
TypePercent of total forest
1970-79
Percent of total forest
1980-89
Percent of total forest
1991-99
Mature49.3255.2651.55
Young22.0918.9021.55
Regenerated21.4714.5616.54
Regenerating7.1211.2810.37

 

Sugar Maple -  yellow birch (east)
Type1970-791980-891991-99
Mature42.1937.8442.61
Young38.9641.9735.75
Regenerated10.7310.3416.77
Regenerating8.129.864.87

Development stages are based on stand height and growth in volume: regenerating = disturbed stands <2 m in height; regenerated = disturbed stands 2–7 m in height; young = stands >7 m with increasing mean annual growth (volume); mature = stands >7 m with decreasing mean annual growth (volume).
Data included area outside the AME.
Source: Ministère des Ressources naturelles et Faune, 2009, Statistiques forestières, unpublished data; updated from Ministère des Ressources naturelles, 2002Footnote25

Top of Page

Forest composition

In many parts of the AME, the forest has been simplified both in species and ecosystem diversity over the past several decades. This was primarily a result of forest clearing for agriculture and subsequent abandonment, timber removal of selected species, and clear-cutting as well as natural disturbance.16

Acadian forest

As older forests were replaced by relatively young, often even-aged, early successional forest types, the abundance and age of late-successional species such as sugar maple (Acer saccharum), red spruce (Picea rubens), eastern hemlock (Tsuga canadensis), red oak (Quercus rubra), yellow birch (Betula alleghaniensis), American beech (Fagus grandifolia), and eastern white cedar (Thuja occidentalis) declined.16, Footnote26 Younger forests have higher frequencies of balsam fir, red maple (Acer rubrum), white spruce (Picea glauca), white birch, and trembling aspen.16, Footnote27 Similar changes are occurring in other eastern forests where species composition was altered by logging and land clearing throughout the twentieth century.Footnote28

A case study in Kings County, NB, compared forest species composition in 1800 and 1993. Species distribution in 1800 was more even than in 1993 (Figure 9).16 The study showed that cedar was likely as common as balsam fir in the early 1800s, but by the 1990s, balsam fir was four times as common as cedar. The spruce genus increased in frequency, as did poplar, and white pine remained stable, but the rest of the other tree genera were more common 200 years ago than today. Cedar, hemlock, ash, beech, and larch declined over the time period. Balsam fir and the spruces comprised about 50% of the forest in 1993, while 200 years ago, they accounted for only 25%.16

Figure 9. Estimated frequency of major forest tree genera in Kings County, NB, 1800 and 1993.

graph

Long Description for Figure 9

This graph shows the estimated frequency of major forest tree genera in Kings County, New Brunswick, in the years 1800 and 1993. In general, species distribution in 1800 was more even than in 1993. The graph shows that, in 1800, spruce, maple and birch make up more than 50%, while the rest is relatively even. In 1993, the amount of spruce, fir and poplar increased substantially. Cedar was likely as common as balsam fir in 1800 but, by 1993, balsam fir was four times as common as cedar. The spruce genus increased in frequency, as did poplar, and white pine remained stable, but the rest of the other tree genera were more common 200 years ago than today. Cedar, hemlock, ash, beech, and larch declined over the time period. Balsam fir and the spruces comprised about 50% of the forest in 1993, while in 1800, they accounted for only 25%.

Source: Loo and Ives, 200316

Forest subdomains in Quebec portion of AME

From the 1970s to 1990s, conifers, particularly balsam fir, in the balsam fir subdomains declined,25 while mixedwood stands increased. In the balsam fir–yellow birch and balsam fir–white birch subdomains, conifer proportions decreased by 8 and 16%, respectively. Conifers in the sugar maple–yellow birch subdomain declined, while mixedwood stands increased (Figure 10). These data include public and private forests, and include all the area of the subdomains, including some area outside the AME.

Figure 10. Proportion of total area covered by different forest cover types in the Quebec subdomains that occur in the Atlantic Maritime ecozone+, 1970s, 1980s, and 1990s.

graph

Long Description for Figure 10

This figure has three bar graphs that show the following information:

Data for figure 10.

Balsam fir - yellow birch (east)
TypePercent of total forest
1970-79
Percent of total forest
1980-89
Percent of total forest
1991-99
Conifer34.6525.7126.96
Mixed37.7039.3143.63
Deciduous19.9825.6124.33
Regeneration7.679.375.07
 Percent of total forest

 

Balsam fir - white birch (east)
TypePercent of total forest
1970-79
Percent of total forest
1980-89
Percent of total forest
1991-99
Conifer70.6158.3454.62
Mixed16.2620.0927.68
Deciduous6.0110.287.33
Regeneration7.1211.2810.37

 

Sugar maple -  yellow birch (east)
TypePercent of total forest
1970-79
Percent of total forest
1980-89
Percent of total forest
1990-99
Coniferous19.6218.1917.20
Mixed37.2738.3643.68
Deciduous34.9933.5934.25
Regeneration8.129.864.87

Forest cover types are based on stand height and composition; regenerating = <2 m in height; deciduous = >75% deciduous; mixed = 25–75% deciduous; coniferous = >75% coniferous. Data included area outside the AME.
Source: Ministère des Ressources naturelles et Faune, 2009, Statistiques forestières, unpublished data; updated from Ministère des Ressources naturelles, 200225

Top of Page

Differences in land cover types were also measured between 1993 and 2001 for the Appalachian Ecoregion which overlaps with parts of the area above. Jobin et al.Footnote29 reported that the abundance of mixedwood forest declined by over 12% while coniferous stands increased by 7% over this time period (Figure 11).

Figure 11. Change in forest types for the Appalachian Ecoregion in southern Quebec between 1993 and 2001.

graph

Long Description for Figure 11

This figure is a bar graph depicting the following information:

Data for figure 11.
TypePercent of forest
1993
Percent of forest
2001
Deciduous32.1732.64
Mixed woods44.1028.07
Coniferous16.7325.85
Regenerating4.1512.79
Harvest/Burn2.850.65

Source: Jobin et al., 200729

Fragmentation

Fragmentation reduces habitat connectivity, increases edge density, and increases the isolation of remnant habitat patches. In contrast to more remote, less populated ecozones+, remaining natural ecosystems of the AME are highly fragmented. Only 5% of the AME is covered by intact fragments of natural ecosystems (primarily forests) larger than 50 km2 (Figure 12).19

Figure 12. Intact landscape fragments larger than 50 km2 in the Atlantic Maritime ecozone+, 2003.

map

Long Description for Figure 12

This map shows the remaining intact landscape fragments in the Atlantic Maritime Ecozone+ larger than 50 km2 in 2003.  In 2003, the landscape was highly fragmented and only 5% was covered by intact fragments of natural ecosystems (primarily forests) larger than 50 km2.  The largest areas of intact forest occurred on the northern tip of Cape Breton, in interior areas of the southern tip of Nova Scotia, and in interior areas of the Gaspé Peninsula.

A landscape fragment is a contiguous mosaic of various ecosystems, naturally occurring and essentially undisturbed by significant human influence.
Source: adapted from Lees et al., 200619

Top of Page

Forest birds

Changes in the age structure of the forest, with increasing early-successional stands and decreasing contiguous mature stands, and the replacement of some hardwood stands with softwood plantations and agricultural land have resulted in changes in the bird community.Footnote30 Footnote31 Overall, forest bird populations have been generally stable but with a tendancy to decline, especially since 2000 (Figure 13). There have been large declines for several species, while others have stable or increasing populations. For example, the Canada warbler (Cardellina canadensis), a species recently assessed as Threatened by the Committee on the Endangered Status of Wildlife in Canada (COSEWIC), has declined by 80% in the AME since the 1970s. Although the primary cause of its decline is unclear, research has shown this species is sensitive to forest fragmentation and human disturbance. Populations may have been affected on both the breeding and wintering grounds by habitat loss and degradation. The decline in spruce budworm (Choristoneura fumiferana) abundance may also have reduced an important food source for Canada warbler.Footnote32 Footnote33 The boreal chickadee (Poecile hudsonicus) has also declined markedly in this region and throughout its range.Footnote34 Footnote35

The AME region in Canada and similar neighbouring areas in the United States support over 90% of the world’s breeding population of Bicknell’s thrush (Catharus bicknelli), one of the rarest songbirds in North America and listed as Threatened in Canada.Footnote36 This bird lives in the high-elevation coniferous forests and is particularly susceptible to climate change, which may result in shifts in high-elevation breeding zones. Other threats incude habitat loss and degradation on both the breeding and wintering grounds, squirrel predation at nests, and environmental contaminants.Footnote37 Footnote38 Footnote39 Surveys over the last several years indicate this species has undergone considerable annual decline.35 Footnote40 Footnote41

Figure 13. Annual indices of population change for birds of forest habitat (left) and shrub-early successional habitat (right), 1968–2006.

graph

Long Description for Figure 13

This figure has two line graphs showing the following information:

Data for figure 13.
Forest habitat
-Year
Forest habitat
- Abundance Index
Shrub-early successional habitat -
Abundance index
1968165.3144.2
1969211.1173.7
1970226.2164.9
1971242.9166.2
1972254.2172.6
1973226.1175.9
1974234.8175.2
1975211.0159.0
1976205.1157.3
1977202.5160.4
1978214.8145.7
1979198.1125.2
1980207.6143.1
1981225.5142.6
1982220.3138.1
1983240.9155.1
1984218.7149.0
1985222.2154.6
1986233.1146.1
1987196.7132.9
1988206.6125.1
1989211.5132.5
1990212.8130.7
1991204.6123.9
1992208.6143.4
1993209.4145.2
1994172.8120.8
1995233.1134.2
1996207.6140.3
1997206.8147.6
1998205.0140.3
1999220.9144.5
2000194.7129.4
2001198.8139.0
2002196.3137.7
2003187.2148.7
2004183.4130.1
2005171.3134.7
2006177.9124.9

Shrub/early successional assemblage includes shrubland, old field, and mid-successional stage habitat from grassland to forest.

Source: Downes et al., 2011Footnote42using data from the Breeding Bird SurveyFootnote43

A large portion of forested land in the ecozone+ is in early successional stages. The overall slightly negative trends in the indices of population change for birds inhabiting forest and shrub-early successional habitat types (Figure 13) were influenced by the strong declines in abundant species such as the white-throated sparrow (Zonotrichia albicollis) and song sparrow (Melospiza melodia). However, declines in these species have been largely balanced by increases in several generalist species, such as Nashville warbler (Oreothlypis ruficapilla), yellow warbler (Setophaga petechia), and chestnut-sided warbler (Setophaga pensylvanica), which utilize and have benefited from increases in shrub-early successional forest habitat.Footnote44

Cumulative human impact

The organization Two Countries One Forest quantified the human footprint on terrestrial ecosystems of the Appalachian/Acadian Ecoregion (which includes the AME) by integrating four categories of human influence: settlement, access, land use, and electrical power infrastructure (Figure 14).Footnote45 In 2008, the greatest human impacts were primarily on coastlines, valleys, and other low-lying areas, reflecting the historical pattern of settlement. Only 0.2% of the ecoregion has a human footprint score of 0, indicating no human transformation of the landscape. More than 90% of the ecoregion has a low human footprint (score of less than 50). Large areas are classified as having low impact; however, they tend to be separated by areas with high levels of human activity, thus fragmenting the region.45 Only 5% of the total landscape is in intact natural fragments of larger than 50 km2.19

Figure 14. The human footprint of the Northern Appalachian/Acadian Ecoregion, 2008.

map

Long Description for Figure 14

This figure is a temperature map showing the degree of human impact over the Northern Appalachian/Acadian Ecoregion (which includes the Atlantic Maritime Ecozone+).  The greatest human impacts have been primarily on coastlines, valleys, and other low-lying areas, reflecting the historical pattern of settlement. Only 0.2% of the ecoregion has a human footprint score of 0, indicating no human transformation of the landscape. More than 90% of the ecoregion has a low human footprint (score of less than 50). Large areas are classified as having low impact; however, they tend to be separated by areas with high levels of human activity indicating fragmentation of the region.

Source: Trombulak et al., 200845

Top of Page

Key finding 3
Wetlands

Theme Biomes

National key finding
High loss of wetlands has occurred in southern Canada; loss and degradation continue due to a wide range of stressors. Some wetlands have been or are being restored.

There has been extensive wetland loss in the AME, particularly in coastal areas, where shoreline development is a continuing threat (see Coastal wetlands section on page 29). Although three of the four provinces in the AME have had wetland inventories completed since the 1980s, wetland mapping and assessment methodologies have changed, making it difficult to determine the amount of change over time.10, Footnote46 According to data from Canada’s Forest Inventory (CanFI),Footnote13 in 2001, wetlands covered approximately 3.5% of the land area of the ecozone+ and approximately 35% of those were treed.10 Although estimates of freshwater wetland losses are not available for the AME as a whole, approximately 16 to 18% of freshwater wetlands in Nova Scotia had been developed or converted to other ecosystem types between European settlement and 1998.Footnote47 Coastal wetland loss in Nova Scotia has been estimated at 65%.Footnote48

Many wetlands in the AME remain under continued threat of loss and degradation due to industrial and urban development, port expansion, cottage subdivisions, and agriculture. However, each of the four provinces have wetland conservation or similar policies that have mitigated the impacts of development projects and land-use decisions to some degree.Footnote49 Bogs are being impacted by commercial peat moss extraction and cranberry production.

Waterfowl

Trends for selected breeding waterfowl species show either stable or increasing populations since 1993 (Table 3).Footnote50 The American black duck (Anas rubripes), the most abundant duck in the AME, has been the focus of special conservation effort because the wintering population in the United States decreased by almost 50% between 1955 and 1985.Footnote51 Footnote52 In the AME, from 1993 to 2006, black duck populations were stable (Table 3).50 Logging, hydroelectric development, transmission line construction, agriculture, urbanization, and industrial development threaten breeding and staging habitats.51 In addition, it is likely that the species has had to compete for habitat with a growing mallard (Anas platyrhynchos) population.Footnote53 Some evidence shows that habitat availability and quality may not be limiting, however,53 and recent increases and stabilization of the black duck may reflect increased hunting restrictions in Canada and the United States.52 Black ducks are also closely related to mallards and the two species interbreed regularly, which may represent an additional conservation concern for the species.Footnote54 Footnote55 Footnote56

Table 3. Abundance trends for selected breeding waterfowl species in the Atlantic Maritime Ecozone+, 1990s–2000s.Table note1
SpeciesNesting habitatTrend
(%/yr)
PAnnual Index (in thousands)
1990s
Annual Index (in thousands)
2000s
Annual Index (in thousands)
% change
Mallard
(Anas platyrhynchos)
Ground30.1*2.34.698.1
American black duck
(Anas rubripes)
Ground2.2 57.763.710.5
Green-winged teal
(Anas crecca)
Ground5.9n8.411.738
Ring-necked duck
(Aythya collaris)
Overwater6.5*21.232.352.2
Canada goose
(Branta canadensis)
Ground22.5*1.13.6244.3

Table 3 - Notes

Table note 1

In this table: P is the statistical significance: * indicates P<0.05; n indicates 0.05<P<0.1; no value indicates not significant
For a description of how species were selected and data methodology, see Fast et al., 2011.
Source: Fast et al., 201150

Return to note1referrer

Top of Page

Key finding 4
Lakes and rivers

Theme Biomes

National key finding
Trends over the past 40 years influencing biodiversity in lakes and rivers include seasonal changes in magnitude of stream flows, increases in river and lake temperatures, decreases in lake levels, and habitat loss and fragmentation.

Of the 1,792 lakes in the Atlantic Provinces, 98% are less than 99 km2 in size.Footnote57 The largest lake in the AME is Grand Lake, NB. The Saint  John River in New Brunswick is the largest river system in the AME.Footnote58 Seven rivers/river systems within the AME are classified as Canadian Heritage Rivers: the Saint John, St. Croix, and Upper Restigouche rivers in New Brunswick; the Shelburne River and Margaree-Lake Ainslie river system in Nova Scotia; and the Hillsborough River and Three Rivers (Cardigan, Brudenell, and Montague/Valleyfield) river system on Prince Edward Island. 58, Footnote59 Runoff increases significantly from west to east, varying from 60 cm annually in the western part of the AME to 200 cm along the Atlantic coast.58 59 Footnote60 Footnote61

Lakes and rivers in the AME support diverse aquatic communities including species at risk such as the Atlantic salmon (Salmo salar), striped bass (Morone saxatilis), Atlantic whitefish (Coregonus huntsmani), American eel (Anguilla rostrata), wood turtle (Glyptemys insculpta), Blanding’s turtle (Emydoidea blandingii), dwarf wedgemussel (Alasmidonta heterodon), yellow lampmussel (Lampsilis cariosa), skillet clubtail (Gomphus ventricosus), cobblestone tiger beetle (Cicindela marginipennis), and several coastal plain flora.

Streamflow in natural rivers

Two analyses of streamflow in rivers with minimal flow control or impact upstream over the past 40 years were conducted for ESTR. Cannon et al.Footnote62 looked at seasonal trends in streamflow at sites across Canada between two periods, 1961–1982 and 1983–2003. To facilitate the analysis of trends nationally, sites were organized into six groups with similar intra-seasonal patterns of flow (hydrology groups). Across sites in the AME, changes in flows between 1961–1982 and 1983–2003 included earlier onsets of spring freshet and decreased summer flows (summer flow period from August to October).62 Monk and BairdFootnote63 found that minimum and maximum flow variables decreased at a high proportion of sites from 1970 to 2005 and the annual 1-day minimum flow occurred later in the year. Although the rise rate decreased significantly at 32% of the sites and the fall rate increased at 29%, no overall trend was found in the variability of annual runoff.63 Figure 15 summarizes the number and direction of significant trends in streamflow variables for the 34 stations analyzed by Monk and Baird63 and Figure 16 shows the results of the Cannon et al.62 analysis of seasonal trends at representative sites.

Figure 15. Summary of the total number of sites displaying increasing and decreasing trends in various streamflow variables in the Atlantic Maritime ecozone+, 1970–2005.

graph

Long Description for Figure 15

This figure is a bar graph showing the number and direction of significant trends in streamflow variables for 34 hydrometric gauging stations in the Atlantic Maritime Ecozone+.  The graph shows that both maximum and, to a lesser extent, minimum flow variables decreased at a high proportion of sites from 1970 to 2005. The rise rate decreased significantly at 32% of the sites and the fall rate increased at 29% of sites.  While this graphs shows a high degree of variability was observed, no overall trend was found in the analysis of annual runoff.

Based on 34 gauging sites. Only sites with significant trends (p<0.1) are shown.
Source: Monk and Baird, 201463

Figure 16. Changes in streamflow between 1961–1982 and 1983–2003 for representative sites of each hydrology group in the Atlantic Maritime ecozone+.

a) location of sites
map

b) Group 4a: Kennebecasis River
map

c) Group 4d: St. Mary’s River
map

d) Group 3a: Saint John River
map

e) Group 6a: Northwest Miramichi River
map

Long Description for Figure 16

This figure is comprised of one small map showing the location of monitoring sites and four line graphs depicting annual changes in streamflow at representative sites for each hydrology group over two time periods: 1961–1982 and 1983–2003.  The four monitoring sites shown are: Kennebecasis River representing Group 4a, St. Mary’s River representing Group 4d, Saint John River representing Group 3a, and Northwest Miramichi River representing Group 6a.  General trends between the two time periods observed across all of the sites shown were earlier onsets of spring freshet and decreased summer flows from August to October.

Hydrology groups represent clusters of rivers showing similar hydrologic responses to variations in climate. For information on the specific hydrology groups mentioned above, see Cannon et al. 2011.62
Source: Cannon et al., 201162

Top of Page

Water control structures

Although water control structures are less common in the AME than in some ecozones+, their impacts are often greater because of the coastal nature of the ecozone+ and large number of  watersheds with limited numbers of natural lakes. Ecological impacts include local and regional species extirpations and habitat loss and alteration. Impacts of these structures on lakes and rivers include altering natural water level fluctuations, peak flows, seasonal flooding, and natural disturbance regimes, as well as decreasing water quality.Footnote64 A total of 74 large dams (greater than 10 m in height) have been constructed in the AME, although few since the 1970s.

Figure 17. Spatial distribution of dams greater than 10 m in height within the Atlantic Maritime ecozone+, grouped by year of completion between 1830 and 2005.

map

Long Description for Figure 17

This map shows the location and age class of dams greater than 10 m in height in the Atlantic Maritime ecozone+.  A total of 74 large dams have been constructed in the ecozone+, although few since the 1970s.

Source: Canadian Dam Association, 2003Footnote65

Examples of the impacts of dams on biodiversity in the AME include:

  • extirpation of three plants, Canadian honewort (Cryptotaenia canadensis), prairie goldenrod [Oligoneuron album (syn. Solidago ptarmicoides)], and American bittersweet (Celastrus scandens) from the Saint John River, NB, due to flooding from hydroelectric dams;Footnote66
  • local extirpation of two species at risk, Plymouth gentian (Sabatia kennedyana) and pink coreopsis (Coreopsis rosea), from at least two lakes in the Tusket River system in extreme southwestern Nova Scotia;Footnote67, Footnote68
  • extirpation of one of only two populations of the endangered Atlantic whitefish (Coregonus huntsmani) in Nova Scotia as a result of the damming the Tusket River in 1929Footnote69 ; and
  • extirpation of the dwarf wedgemussel (Alasmidonta heterodon), a species that was restricted to the AME in Canada, likely as a result of the loss of its fish host due to construction of a causeway over the tidal portion of the Petitcodiac River, NB, in 1967–1968.Footnote70 Footnote71

Top of Page

Key finding 5
Coastal

Theme Biomes

National key finding
Coastal ecosystems, such as estuaries, salt marshes, and mud flats, are believed to be healthy in less-developed coastal areas, although there are exceptions. In developed areas, extent and quality of coastal ecosystems are declining as a result of habitat modification, erosion, and sea-level rise.

The coast is a defining feature of the AME. Coastal features include bays, coves, harbours, inlets, passages, channels, basins, points, heads, promontories, islands, capes, beaches, barrens, estuaries, and salt marshes.Footnote72 There is some information on the status of coastal features in the AME, however, trends in this biome are not well known. Where data exist, they are not comprehensive and not necessarily representative of the entire AME. Given these caveats, available data suggest that coastal wetlands, beaches, and dunes declined and that stressors, such as development (industrial, urban, and cottage development),Footnote73 recreation, sea-level rise, and storm surges increased. Climate change will increase impacts to these coastal habitats.73 Some coastal dependent species, such as certain shorebirds, also declined.

Coastal wetlands

Although coastal wetlands and shores cover less than 1% of the AME, they are one of the most important habitat types for maintaining native biodiversity. Loss and fragmentation of this ecosystem type in the AME is one of the most severe cases of wetland loss in Canada.27 As already mentioned in the Wetlands section (page 24), an estimated 65% of the area covered by coastal marshes has been lost since European settlement.48 Wetland loss began over 300 years ago when Acadians began draining salt marshes for agriculture. Since 1900, many coastal wetlands have been drained, flooded, and/or filled in for urban, industrial, or agricultural purposes and coastal developments, particularly cottage subdivisions.Footnote74

Hanson et al.Footnote75 quantified change in the extent of salt marshes in two undeveloped (Cape Jourimain and Shemogue) and three developed (Aboiteau, Shediac, and Cocagne) sites along the Northumberland Strait in southeastern New Brunswick between 1944 and 2001. Salt marshes declined at all five sites over the study period from a combination of development and climatic variables (Figure 18).

Figure 18. Decline in area of vegetated salt marsh in five locations in southeastern New Brunswick between 1944 and 2001.

graph/map

Long Description for Figure 18

This map and bar graph depict the following information:

Data for figure 18.- Percent change
Cape Jourimain (1)Shemogue (2)Aboiteau (3)Shediac (4)Cocagne (5)
-28%-5%-27%-21%-36%

Study sites Cape Jourimain (1) and Shemogue (2) are undeveloped areas. The other three sites (3–5) are largely residential.
Source: adapted from Hanson et al., 200675

Coastal wetlands continue to be degraded as a result of terrestrial runoff and sedimentation, the restriction of tidal water movement due to barriers and culverts,73 and the rise in sea levels due to climate change. Industrial and commercial development, as well as some agricultural practices, are among the principal threats to estuarine ecosystems.Footnote76 Continued sea-level rise will result in additional negative impacts on the coast73 (see Sea-level rise and coastal erosion section on page 36).

Eelgrass

Eelgrass meadows are among the most productive ecosystems in the world,Footnote77 and also among the most threatened.Footnote78 Eelgrass (Zostera marina) is an important food for migrating and wintering waterfowl, and provides foraging areas for other birds.Footnote79, Footnote80, Footnote81 Comprehensive trend data do not exist for eelgrass but compiling results from a number of mainly short-term studies (Table 4) suggests a general decline in eelgrass and some abrupt die-offs, along with some areas with stable to increasing trends.Footnote7780 Loss of eelgrass beds worldwide have been attributed to a range of natural and human-induced disturbances, including coastal erosion, hurricanes, sediment and nutrient loading (see Nutrient loading and algal blooms section on page 52), and various forms of mechanical disturbance.Footnote82 Another factor in declines on the Atlantic coast is the spread of the invasive green crab (Carcinus maenas), which can uproot eelgrass plants.Footnote83

Table 4. Trends in eelgrass from studies in Nova Scotia and the Gulf of the St. Lawrence.
LocationYearsEelgrass trends
Lobster Bay, NS1978–2000Estimated losses of 30 and 44% in two areasFootnote84
Antigonish Harbour, NS2000–2001Biomass decline of 95% followed by 50% decline in geese and ducks that feed on the eelgrassFootnote85
4 Nova Scotia inlets1992–2002Loss of 80% of total intertidal area occupied by eelgrassFootnote86
13 southern Gulf of St. Lawrence estuaries2001–2002Biomass decline of 40%Footnote87
Gulf of St. Lawrence in QuebecvariousManicouagan Peninsula distribution expanded (1986 to 2004); generally also expanding or stable in other areasFootnote88

Shorebirds

Although the AME supports a number of breeding shorebird species, it is most important for migrant shorebirds. Coastal habitats, particularly those around the upper Bay of Fundy, are of critical importance as stopover and refueling areas, particularly for the smaller sandpipers.Footnote89, Footnote90, Footnote91 The number of shorebirds passing through the Canadian Atlantic provinces declined since surveys were started in 1974 (Table 5),.Footnote92 9.Footnote3, Footnote94, Footnote95, Footnote96 with declines particularly pronounced in the 1990s.Footnote97 The reasons for the declines are not fully understood. Although coastal habitats have changed in ways that can negatively affect shorebirds,Footnote98 trends in at least some species likely reflect factors in other parts of the birds’ migration ranges.98

Table 5. Trends in abundance of shorebirds migrating through coastal areas of the Atlantic Maritime Ecozone+, 1974–2006.Table note1
SpeciesTrend
(%/yr)
PAbundance index
1970s
Abundance index
1980s
Abundance index
1990s
Abundance index
2000s
Change
%
Red knot
(Calidris canutus)
-10.9*39.511.29.13.3-97.5
Least sandpiper
(Calidris minutilla)
-6.6*80.722.29.811.6-88.8
Lesser yellowlegs
(Tringa flavipes)
-5.0*29.252.216.49.8-80.6
Semipalmated sandpiper
(Calidris pusilla)
-4.9 5170.948922623.73074.5-80.0
Black-bellied plover
(Pluvialis squatarola)
-3.0*51.043.123.026.7-62.3
Dunlin
(Calidris alpina)
-2.8 26.328.611.415.5-59.7
Ruddy turnstone
(Arenaria interpres)
-2.8**13.210.911.44.2-59.7
Short-billed dowitcher
(Limnodromus griseus)
-2.7 292.8281.739.6141.0-58.4
Sanderling
(Calidris alba)
-2.3 42.934.719.824.0-52.5
Greater yellowlegs
(Tringa melanoleuca)
-0.9 13.012.89.810.8-25.1
Hudsonian godwit
(Limosa haemastica)
-0.9 5.54.13.52.9-25.1
Willet
(Tringa semipalmata)
-0.8 16.615.911.114.1-22.6
White-rumped sandpiper
(Calidris fuscicollis)
-0.2 16.115.312.616.4-6.2
Semipalmated plover
(Charadrius semipalmatus)
1.9 103.8123.0153.1159.382.6
Whimbrel
(Numenius phaeopus)
2.5 1.91.53.14.3120.4

Table 5 - Notes

Table note 1

In this table: P is the statistical significance: ** indicates P<0.01, * indicates P<0.05, no value indicates not significant “Change” is the percent change in the average abundance index over the entire period calculated from the overall trend (%/yr).
Source: Gratto-Trevor et al., 201197

Return to note1referrer

Relatively few species of shorebirds breed in the AME, and only a small number in coastal areas. Of the four coastal breeding species in the AME for which trends can be determined from Breeding Bird Survey data (Table 6), only the trend for Wilson’s snipe (Gallinago delicata) was significant, declining at 2.6%/yr (P<0.01).97

Table 6. Trends in abundance of coastal breeding shorebirds, 1970s to 2000s.Table note1
SpeciesTrend
(%/yr)
Abundance index
1970s
Abundance index
1980s
Abundance index
1990s
Abundance index
2000s
Change
%
Upland sandpiper
(Bartramia longicauda)
-3.1 30.20.10.1-70%
Spotted sandpiper
(Actitis macularius)
-2.6 0.80.90.70.4-64%
Willet
(Tringa semipalmata)
-3.1 1.110.40.4-71%
Wilson's snipe
(Gallinago delicata)
-2.6**5.24.82.92.3-64%

Table 6 - Notes

Table note 1

In this table: P is the statistical significance: ** indicates P<0.01, no value indicates not significant Change indicates the percent change in the average abundance index over the survey period (1968–2006) calculated from the overall trend (%/yr).
Source: Gratto-Trevor et al., 201197 using data from the Breeding Bird Survey43

Return to note1referrer

Top of Page

Waterfowl

The AME has many coastal areas where large numbers of waterfowl traditionally congregate during the spring and fall migrations.Footnote99 Many waterfowl also winter in this region, for example, Barrow’s goldeneye (Bucephala islandica).Footnote100 Recent milder winters with longer ice-free periods have resulted in larger wintering populations and potential increases in the residency times of waterfowl during migration.Footnote101 Trends in breeding waterfowl are summarized in the Wetlands section on page 24.

Sandy shores and sand dunes

Sandy shores and sand dunes are primarily located along the New Brunswick coast of Northumberland Strait, the Minas Basin, the north shore of PEI, and Îles de la Madeleine. Beaches and dunes are important habitat for many species of wildlife, providing food and habitat to shorebirds and other fauna, flora, and microorganisms.76 They are threatened by development, sand mining, recreation, sea-level rise, and increased storm severity related to climate change (see Sea-level rise and coastal erosion section on page 36).

Data on trends in erosion and deposition rates for beach and dune habitat is limited. O’Carroll et al.Footnote102 conducted a retrospective analysis of aerial photos to assess temporal changes in beach and dune habitat at five locations in southeastern New Brunswick between 1944 and 2001. They found that the amount of beach and dune habitat had declined in all sites, with a greater decline in beach than in dune in all five locations (Figure 19). Sand removal for aggregate production and the expansion of shoreline protection have also contributed to changes in these areas. The variety of changes observed illustrates that local accretion and erosion processes, storm events, and human activity have all been important factors in shaping coastal sand ecosystems.102

Figure 19. Decline in area of beach and dune habitat in five locations in southeastern New Brunswick between 1944 and 2001.

graph/map

Long Description for Figure 19

This map and bar graph depicts the following information:

Data for figure 19.
Cape Jourimain (1)
Percent change
Shemogue (2)
Percent change
Aboiteau (3)
Percent change
Shediac (4)
Percent change
Cocagne (5)
Percent change
-22%-8%-12%-32%-40%

Study sites Cape Jourimain (1) and Shemogue (2) are undeveloped areas. The other three sites (3–5) are largely residential. For Shediac, the 32% decline was between 1944 and 1971 with little additional loss between 1971 and 2001.
Source: adapted from O’Carroll et al., 2006102

Piping plover

The Atlantic population of piping plovers (Charadrius melodus melodus), listed as Endangered under Canada’s Species at Risk Act, prefers early-successional habitat, such as barrier islands converted from sand spits by storm activity (Figure 20).73 In 2002, the global piping plover breeding population was estimated at only 5,945 adults.Footnote103 In the AME, 442 adults in 2001 and 435 adults in 2006 were detected at breeding sites. Despite active conservation programs there was been a 13% decline in the number of adults from 1991 to 2006 (Figure 20). There are several threats to piping plovers, with predation being one of the most important factors limiting populations across the North American breeding range. Current estimates in eastern Canada suggest that hatching success is less than 55%.Footnote104 In addition, habitat loss and degradation are significant problems. Increased use of beaches and coastal development, including construction of cottages or homes, wharves, jetties, and erosion control structures can impact nesting beaches as well as brood-rearing and foraging habitat.Footnote105 Impacts from climate change are another factor, including storm surges, which are becoming more frequent, and sea-level rise.Footnote106, Footnote107

Figure 20. Distribution of 2006 piping plover nesting sites (left, map) and the number of piping plover adults counted during surveys (right, bar chart) in the Atlantic Maritime ecozone+, 1991, 1996, 2001, and 2006.

map/graph

Long Description for Figure 20

This figure is comprised of a map that shows the distribution of piping plover nesting sites and a bar graph that shows the number of adults counted during International Piping Plover Censuses between 1991 and 2006 at survey sites in the Atlantic Maritime Ecozone+.  Nesting sites in the ecozone+ are concentrated along the southwest coast of Nova Scotia as well as the north coast of Prince Edward Island.  The graph shows the following information:

Data for figure 20. - Number of adults
1991199620012006
761047082

Count data from International Piping Plover Censuses 1991–2006. Numbers reported reflect “high counts” and include all adults counted during all surveys at all sites (some sites surveyed multiple times).
Source: map from Environment Canada, 2006;106 data from Ferland and Haig, 2002103 and Elliot-Smith et al., 2009Footnote108

Coastal development

Since 1990, coastal areas of the AME have become more heavily populated. In New Brunswick, for example, the proportion of coastal subdivisions as a percentage of all subdivisions in the province increased 35% from 1990 to 1999.Footnote109 In Nova Scotia, increased urbanization led to population declines in many rural areas of the province, while populations increased along the coast. There was a dramatic increase in the rates of subdivision and lot registrations on coastal land through the 20th century (Figure 21).76

Figure 21. Trends in lot registration within two km of the Nova Scotia coastline by decade.

graph

Long Description for Figure 21

This graph shows following information:

Data for figure 21.
YearNumber of
registrations
Before 18891,000
1889-19081,500
1909-1918800
1919-1928500
1929-19381,100
1939-19482,600
1949-19585,100
1959-196814,500
1969-197841,500
1979-198857,500
1989-199874,500
1999-200869,500

Source: adapted from Nova Scotia Property Online Database by CBCL Limited, 200976

Sea-level rise and coastal erosion

Rates of sea-level rise depend on several factors, including the rate of glacier and ice cap melting, the warming of ocean waters, and isostatic rebound, which is the vertical movement of the Earth’s crust.Footnote110 A national overview of coastal sensitivity to sea-level rise and associated storm impacts demonstrated that the Atlantic region has some of Canada’s most severely threatened coastal areas.Footnote111 Approximately 80% of the coastline is considered highly sensitive. Its most sensitive coastlines are generally low-lying areas with salt marshes, barrier beaches, and lagoons.

Over the past century, sea level in the Atlantic region has been rising; several harbours have experienced average rise rates of between 22 and 32 cm/century (Figure 22). Average sea level along the coastline of eastern Quebec  rose by 17 cm over the last century.107Footnote112 A portion of sea-level rise is likely due to land subsidence after glacier retreat, but much is due to sea-level rise from changing climate. For example, from 1911 to 2005, the annual mean sea level at Charlottetown rose at an average rate of 32 cm/century.107 Of this, approximately 20 cm/century was likely due to land subsidence after glacier retreat and the remaining 12 cm/century was due to sea-level rise.107 Footnote113

Figure 22. Trend in annual mean water level in six harbours in the Atlantic Maritime ecozone+.

graph

Long Description for Figure 22

This figure is composed of six line graphs with trend lines showing the rate of sea level rise for harbours in the Atlantic Maritime Ecozone+.  Sea levels increased at similar rates in all six harbours. The graphs show the following information:

Data for figure 22.
HarbourYearsTrends (cm/century)
Halifax, NS1920-200832
North Sydney, NS170-200830
Yarmouth, NS1967-200830
Pictou, NS1966-199524
Charlottetown, PEI1911-200832
Saint John, NB1906-200822

Source: CBCL Limited, 200976using data from Marine Environmental Data Service, Ottawa, 2008Footnote114

One of the primary impacts of rising sea levels is an increase in coastal retreat or coastal erosion. Although coastal erosion is a natural phenomenon, rising sea levels as well as other climate change-related impacts to physical and climatic processes will accelerate erosion rates in parts of the AME, such as the Gulf of St. Lawrence.Footnote115 Footnote116 Accelerated coastal erosion is correlated with changes in climatic variables such as increased storm frequency,115 Footnote117 shorter ice season, more freeze/thaw cycles and winter rain events,Footnote118 and higher sea levels.116 The most sensitive areas to coastal erosion within the AME are on the Gaspé Peninsula, at the entrance of the Baie des Chaleurs, and around PEI and Îles de la Madeleine.

In some areas of PEI, there is already evidence of a significant increase in coastal erosion rates. For example, erosion rates at Pigots Point, Savage Harbour were 1.4 m/yr from 1968 to 1981 and 3.2 m/yr from 1981 to 1990. This is not necessarily the case throughout the AME, however. In 2006, Environment Canada quantified sea-level rise, storm surge, and coastal erosion on the region’s Gulf of St. Lawrence coastal zone and found that coastal retreat rates for southeastern New Brunswick did not increase significantly during the second half of the 20th century.107

In addition to erosion, other impacts on ecosystems from sea-level rise include higher and more frequent flooding of wetlands and adjacent shores, expanded flooding during severe storms and high tides, accelerated coastal (dune and cliff) retreat or erosion, breaching of coastal barriers and destabilization of inlets, saline intrusion into coastal freshwater aquifers, and damage to coastal infrastructure. Increased storm surge activity also has implications for coastal erosion and flooding (see Natural disturbance section on page 73).

Top of Page

Key finding 7
Ice across biomes

Theme Biomes

National key finding
Declining extent and thickness of sea ice, warming and thawing of permafrost, accelerating loss of glacier mass, and shortening of lake-ice seasons are detected across Canada’s biomes. Impacts, apparent now in some areas and likely to spread, include effects on species and food webs.

Although ice is not a defining feature of the AME, it can provide important habitat for species adapted to living in, under, and on top of ice, and provide crossing points for land animals, and help to regulate water circulation. The timing and duration of ice cover on rivers, lakes, and the ocean are important factors in the types of plants and animals that water bodies can support.

River and lake ice

Information on overall trends in river and lake ice break-up and freeze-up in the AME was limited and inconclusive,63, Footnote119 Footnote120 Footnote121 and trends were limited to individual rivers or lakes (Table 7.1 and table 7.2).Footnote122 Of the ten sites covered by a recent analysis of data from the volunteer IceWatch program, only one trend, toward a later ice thaw date, was detected from 1950 to 2005.122

Table 7.1 Trends in lake freeze-up dates from studies in the Atlantic Maritime Ecozone+.
Freeze upDatesChange over time periodTrend per yearSignificance
Grand Lake, NB1201952–198017.4 days earlier0.6 days/year<0.1
Lake Utopia, NB1201971–200037.5 days later1.25 days/year<0.001

 

Table 7.2 Trends in lake break-up dates from studies in the Atlantic Maritime Ecozone+.
Break upDatesChange over time periodTrend per yearSignificance
Lake Utopia, NB1201961–199015.6 days earlier0.5 days/year<0.01
Miramichi River, NB1211829–19557.3 days earlier/100 years <0.01
Saint John River, NBFootnote1231950s–1980s15 days earlier ?

Sources are indicated as reference numbers after the name of the lake/river.

Prowse and CulpFootnote124 provided a review of the effects of ice on instream ecological communities. In general, the life cycles of many aquatic organisms are both directly and indirectly influenced by ice through factors such as ice cover duration, instream temperatures, and hydrological variability. For example, Cunjak et al.Footnote125 demonstrated that the interannual variability in the juvenile survival of Atlantic salmon (Salmo salar) in Catamaran Brook, NB, generally improved with increasing average winter flow but the lowest measured survival was associated with an atypical winter breakup and ice jam triggered by rain-on-snow snowmelt events.

Sea ice

Sea ice is important in the AME as it is believed to have a dampening effect on wave action that causes coastal erosion and flooding.107 In parts of the AME that have sea ice annually, ice cover varies from year-to-year; cycles are apparent and have some correlation with the North Atlantic Oscillation, a phenomenon of fluctuations in the difference in atmospheric pressure between the Icelandic Low and the Azores High, which in turn influences wind strength and direction. In the Gulf of the St. Lawrence, sea ice has shown a tendency toward decreasing ice cover and length of the ice season but these trends were not significant (Figure 23).107 Saucier and SennevilleFootnote126 suggest that winter sea ice will be gone from the Gulf of St. Lawrence before the end of the 21st century, which could result in significant coastal erosion, including loss of coastal marshes (see Coastal section on page 29).

Figure 23. Trend in total accumulated ice coverage (top) and length of season (cover >10%) (bottom) for the Gulf of St. Lawrence, 1971–2005.

graph

Long Description for Figure 23

Figure 23 shows two line graphs depicting the trend in accumulated ice coverage and the length of season where ice coverage is above 10% on the Gulf of the St. Lawrence.  Both graphs show levels at yearly increments between 1971 and 2005 as well as a trend line.  The graphs show that sea ice cover area and duration has shown a tendency toward decreasing ice cover and length of the ice season but these trends were not significant

Source: Forbes et al., 2006.107

Top of Page

 

Introduction