Overview 2014

The St. Lawrence hydrographic system, including the Great Lakes, is one of the largest in the world. Its surface area of 1.6 million km² is the third largest in North America, after the Mississippi and Mackenzie rivers. It drains more than 25% of the Earth’s freshwater reserves and influences the environmental processes of the North American continent. Over 30 million Americans and 15 million Canadians live in this immense basin. (Source: 2008 Overview

Long Description

The map show the hydrographic system of the Great Lakes (Lake Superior, Lake Michigan, Lake Huron, Lake Erie, Lake Ontario) and the various sections of the St. Lawrence River. The freshwater fluvial segment extends from Cornwall to Pointe-du-Lac and is characterized by a series of three freshwater riverine lakes. The riverine estuary extends from Pointe-du-Lac to the point on Île d’Orléans and is characterized by freshwater. The head of the upper estuary marks the transition from freshwater to brackish water then salt water downstream from Baie-Saint-Paul to the mouth of the Saguenay. The river finally extends towards the lower estuary and the Gulf.

Long Description

In the freshwater ecosystem, we can see a cross-section of the river with the various key elements of the aquatic ecosystem, i.e., the fish community, the benthic invertebrate community, the wetland plants and the Great Blue Heron. On the water and on the shorelines, we see the elements of human pressure from fishing, agriculture, industry, and wastewater discharges. In the marine ecosystem, we can see phytoplankton, zooplankton, the Beluga Whales, seabirds, and shellfish beds. And on the water and the shorelines, we see commercial fishing, the flowering of red algae, agriculture and wastewater discharges that can contribute fecal coliforms (E coli).

Long Description

This figure represents the distribution of the state of each indicator on a scale from poor to good. Each indicator is identified by a symbol and the coloured circle around it is the same colour as the status it represents. The classes of states are as follows: poor (red), moderate-poor (orange), moderate (yellow), moderate-good (yellowish green), and good (green). The upper part represents indicators for the marine environment, i.e. the upper estuary, the lower estuary and the Gulf, and the lower part represents the fluvial section and estuary.

Throughout the St. Lawrence, certain indicators seem to actually be more sensitive to change than others. The reintroduction of the Striped Bass saw remarkable progress, from a poor state in 2003 to a moderate-good state in 2014. However, several indicators have worsened recently, primarily in the upper estuary, the lower estuary and the Gulf of St. Lawrence. The Beluga Whale population declined dangerously from a moderate state in 2008 to a poor state in 2014, and the Northern Gannet population also declined to a worrisome degree from a good state in 2003 and 2008 to a moderate-poor state in 2014.

Long Description

Each overview (2003, 2008 and 2014) is represented as a pie chart based on its distribution of the state of each indicator. The classes of states are as follows: poor (red), moderate-poor (orange), moderate (yellow), moderate-good (yellowish green), and good (green). In 2003, the distribution was as follows: 8.3% good, 33.3% moderate-good, 33.3% moderate, 16.7% moderate-poor and 8.3% poor. In 2008, the distribution was as follows: 8.3% good, 25% moderate-good, 58.3% moderate, 8.3% moderate-poor and 0% poor. In 2014, the distribution was as follows: 0% good, 41.7% moderate-good, 41.7% moderate, 8.3% moderate-poor and 8.3% poor.

* The finding on the left corresponds to the Lake Saint-Pierre archipelago, and the one on the right to the north and south shores of Lake Saint-Pierre.
** This finding concerns only the section located between the cities of Bécancour and Batiscan.

Long Description
We can see a cross-section of the river with various key indicators of the freshwater aquatic ecosystem based on the categories of water and biological resources, each indicator being represented by its respective symbol. The water element is represented by water flows and levels and the physical chemistry and bacteriology of the water; the biological resources are represented by the fish community, the benthic invertebrate community, invasive plants in the wetlands, and the wetlands.

Long Description

The chart presents the daily flow curves calculated at Sorel in cubic metres per second for the years 2008, 2009, 2010, 2011 and 2012. The Y axis represents the Julian days (January 1 to December 31). In 2008, the flows varied between 7,700 and 15,800 m3/s; in 2009, between 8,300 and 15,200 m3/s; in 2010, between 7,200 and 12,400 m3/s; in 2011, between 8,100 and 14,700 m3/s and in 2012, between 7,000 and 14,300 m3/s. The years 2008, 2009 and 2011 resemble one another with annual average flows that are near the historical average, whereas the flows observed in 2010 and 2012 are lower.

A healthy aquatic ecosystem includes a quantity and quality of water that provides a space for biological communities to live, feed and reproduce, allowing for the creation of a biological diversity of species in benthic and fish communities and among wetland plants. A healthy aquatic ecosystem maintains its structure, processes and ecological functions and allows for resilience to change while conserving a natural variability. Within an aquatic ecosystem, there are numerous complex links within the food webs, with the various elements acting on each other. It is therefore difficult, in a monitoring study, to identify the causes of the changes observed in the ecosystem. In this regard, research work can provide more explanatory elements regarding cause and effect.

Long Description
The chart presents the daily flow curves calculated at Sorel in cubic metres per second for the years 2008, 2009, 2010, 2011 and 2012. The Y axis represents the Julian days (January 1 to December 31). In 2008, the flows varied between 7,700 and 15,800 m3/s; in 2009, between 8,300 and 15,200 m3/s; in 2010, between 7,200 and 12,400 m3/s; in 2011, between 8,100 and 14,700 m3/s and in 2012, between 7,000 and 14,300 m3/s. The years 2008, 2009 and 2011 resemble one another with annual average flows that are near the historical average, whereas the flows observed in 2010 and 2012 are lower.

The St. Lawrence River is fed by two main controlled watersheds: the Great Lakes and the Ottawa River. The flow at the outlet of Lake Ontario near Cornwall generally varies between 6000 and 9000 m³/s over the course of a year (average annual flow: 7060 m³/s), whereas the outflow of the Ottawa River at Carillon varies between 1000 and 8000 m³/s (average annual flow: 1910 m³/s). Several tributaries also contribute to the flow of the river on its way to the estuary, the largest being the Richelieu and Saint-Maurice rivers.

The flow of the St. Lawrence varies a lot from year to year and is dependent on the inter-annual variations in water inflows to Lake Ontario, which are themselves dependent on climate conditions. Over the last few decades, the St. Lawrence water flow pattern has been modified through several human interventions, the consequences of which, whether local or extended, have had a direct impact on water levels. Therefore, using the level as an indicator of water quantity in the St. Lawrence remains useful but is limited in scope. The river’s flow is therefore a better indicator of the state of its hydrology.

For the 2008-2012 period, the inter-annual and seasonal variation has been significant (Figure 7). The years 2008, 2009 and 2011 resemble one another, with annual average flows that are near the historical average, whereas the flows observed in 2010 and 2012 are lower. Among other things, the freshet observed in 2010 was very low, with a flood peak that was nearly non-existent and subsequent flows that were very low until mid-summer. In 2012, the high water came early and the flows dropped quickly afterward, resulting in values that were below the bar of 7500 m³/s for an extended period starting in mid-summer.

Long Description

The map shows the geographic location of sampling sites for the physical and chemical, and bacteriological quality of the water in the fluvial section from Lake Saint-François to Quebec City, from 2008 to 2010. The colour green corresponds to good or satisfactory water quality, which is not of concern, yellow corresponds to questionable water quality, which is to be monitored, and red represents poor or very poor water quality, which is of concern. The sites are then grouped in pie charts by section of the river. Lake Saint-François and Lake Saint-Louis: green (100%); Montréal-Sorel section: green (64%), yellow (9%) and red (27%); fluvial estuary: green (71%) and yellow (29%). The overall finding associated with the indicator is moderate-good.

The finding regarding water quality in terms of physical, chemical and bacteriological parameters is moderate-good, a slight decrease since the last report. We see a decrease in bacteriological quality, the result of an increase in flow and untreated wastewater overflows following more significant precipitation over the last few years. In effect, average annual precipitation recorded from May to October in southern Quebec increased from 2000 to 2010. The annual percentage for stations at good or satisfactory remained above 59% from 1995 to 2010, but rose to 75% between 2003 and 2005 and 67% from 2008 to 2010.

Water quality at Québec depends on pollution sources located upstream, but is also influenced by precipitation and flow. This station makes it possible to briefly summarize what is happening in the fluvial St. Lawrence. From 1995 to 2010, we do not see any significant trends in findings regarding concentrations of suspended solids and phosphorous. However, we do see a slight rise in concentrations of fecal coliforms, with the estimated values rising from 107 UFC/100 mL at the start of the period to 171 UFC/100mL at the end of 2010.

Long Description

The map shows the geographic situation of sampling sites for benthic macroinvertebrates in the fluvial section extending from Lake Saint-François to Lake Saint-Pierre, from 2004 to 2010. The colour green corresponds to a state similar to or of better quality than the reference sites, yellow corresponds to a state that diverges slightly from the reference (between the 25th and 10th percentile or the 75th and 90th percentile), and red represents the most disturbed sites, where the quality diverges greatly from the reference (< 10th percentile or > 90th percentile). The sites are then grouped in pie charts by section of the river. Lake Saint-François: green (84%), yellow (8%) and red (8%); Lake Saint-Louis: green (98%) and yellow (2%); Montréal-Sorel section: green (65%), yellow (19%) and red (16%); Lake Saint-Pierre: green (55%), yellow (26%) and red (19%). The overall finding associated with the indicator is moderate.

The general finding for the benthic macroinvertebrate communities indicator in the fluvial section is moderate, the same finding as for data from Lake Saint-Pierre in 2004. Three parameters are considered for findings for this community: the number of taxa, the percentage of mayflies, stone-flies and caddisflies (groups of insects sensitive to pollution), and the percentage of oligochaetes (group of worms tolerant to pollution). To determine the state of a site, the criteria were established based on data from reference sites considered to be less disturbed sites. The colour green thus corresponds to a state similar to or of better quality than the reference sites; the colour yellow corresponds to a state that diverges slightly from the reference (between 25^th and 10^th percentile or between 75^th and 90^th percentile); and the colour red represents the most disturbed sites, which diverge the most from the reference (< 10^th percentile or > 90^th percentile). Although the parameters retained assess different properties of the benthic communities, they react in a similar manner. Once combined, we see that the most degraded benthic communities are in the fluvial section, in the Berthier-Sorel archipelago and, to a lesser degree, on the north shore of Lake Saint-François.

Long Description

The map shows the pie charts illustrating the distribution of the indicator for the health of fish communities. The colour green corresponds to a good indicator, yellow represents a moderate indicator, orange corresponds to a poor indicator and red represents a very poor indicator. Lake Saint-François: yellow (11%), orange (77%) and red (12%); Lake Saint-Louis: yellow (50%) and orange (50%); Berthier-Sorel archipelago: yellow (22%) and orange (78%); Lake Saint-Pierre: yellow (68%) and orange (32%); Bécancour-Batiscan: green (13%), yellow (63%) and orange (24%). The overall finding associated with the indicator is moderate.

The fluvial St. Lawrence ecosystem, which is unique in North America, gradually turns into an estuary and then an inland sea before flowing into the Atlantic. The 118 species of freshwater fish found there reflect its diversity and full complexity. Of these species, about 15 migratory species use saltwater and freshwater habitats alternatively to complete their life cycles. More than half of these species are in a vulnerable situation due to the anthropogenic problems that they encounter in freshwater.

Since 1995, the RSI, a fish-monitoring network operated by the MFFP, collects a large quantity of standardized and reproducible data regarding fish and their habitats in the fluvial section of the St. Lawrence. Through the use of an index of biotic integrity (IBI) and other methods, those data are used to evaluate the health of fish communities. The IBI uses 12 descriptors, including the diversity of species, their abundance relative to certain trophic levels (insectivore, omnivore, piscivore, etc.), the contribution of species that tolerate or do not tolerate pollution, and the prevalence of external anomalies on fish (La Violette et al. 2003).

The results of the IBI suggest that the health of fish communities in the fluvial St. Lawrence has remained stable overall since 1995, within low-to-moderate values (Figure 10). A detailed analysis of the indicator shows a high level of variability between the various sections of the river, showing some improvements or deteriorations locally in the health of fish communities.

It is important to note that the IBI integrates an amalgam of information and thus provides an overview of the state of fish communities in the St. Lawrence River. To refine that evaluation, a detailed analysis by species remains essential to shed light on certain highly contrasting trends between species and sectors (Table 2). For instance, an increase in the abundance of Lake Sturgeon has been observed in the St. Lawrence River over the last decade. As well, the discovery of new spawning grounds and the return of the species to certain abandoned spawning grounds confirms that the Lake Sturgeon situation is improving in the St. Lawrence. The reintroduction of the Striped Bass following its disappearance from the estuary in the late 1960s is also well under way, and the species is reproducing naturally (see the indicator for the Striped Bass). On the other hand, the American Eel has seen a significant decline in the St. Lawrence in recent years. Between 1983 and 2000, in the upstream portion of the St. Lawrence, the number of young eel running toward the Great Lakes fell by 99.8% at the fishway at the Moses-Saunders Dam in Cornwall. Since that time, the abundance has increased at that location and now varies between 40 000 to 50 000 young fish per year. The loss of fluvial rearing habitat due to the construction of dams, mortality due to hydroelectric plant turbines, and fisheries operations are some examples of factors that have contributed to the decline in the eel population.

The abundances measured by means of gill net are presented for various age groups in order to shed light on the failure to recruit the species. It should be noted that a five-year moratorium on the commercial and sport fishing of Yellow Perch was ordered for Lake Saint-Pierre in 2012.

Long Description
The figure presents a series of maps of Lake Saint-Pierre, which correspond to 5 different sampling periods for 1- and 2-year-old Perch: 2002, 2007, 2009, 2011 and 2013. The abundances measured by means of gill nets are presented for various age groups in order to shed light on the failure to recruit the species. It should be noted that a five-year moratorium on the commercial and sport fishing of Perch was ordered for Lake Saint-Pierre in 2012. On the maps, circles of different sizes represent the abundance, i.e. the number of captures per station (0, 1–5, 6–10, 11–25 and 26–65). From 2002 to 2013, we saw a decrease in the number of Perch sampled. From 2002 to 2007, that decrease was quite significant for 1-year-old Perch, and was very significant for 2-year-old Perch from 2009 to 2011. In 2013, the majority of stations showed an abundance of nil or very low.

The status of Yellow Perch is very different upstream, for instance in lakes Saint-François and Saint-Louis, near Montréal, where Yellow Perch are abundant and support sustainable sport fishing. In Lake Saint-Louis, Yellow Perch have been re-established, particularly over the past 20 years, and particularly on the south shore, where efforts to reduce industrial emissions seem to have been successful. The findings between the various sections of the river are explained by the fact that there is additional pressure on fish populations in Lake Saint-Pierre. The decline of the Yellow Perch population, which occurred despite several strict management measures aimed at reducing and then eliminating fish mortality, now suggests the need for an examination of other possible solutions in order to return to the support capacity that existed in the past.

The state of Walleye stocks evaluated in 2010 indicates a decline in populations in the St. Lawrence River. In Lake Saint-François and downstream from the Laviolette bridge in Trois-Rivières, populations are declining due to the modification of the habitat and pressure from fishing. However, the Walleye population in Lake Saint-Louis is in good health. The species is considered to be at risk in Lake Saint-Pierre, where an increase in the mortality rate and decrease in the abundance of mature females have been noted. A management plan for the species was implemented in 2011 throughout Quebec in order to improve the state of stocks and the quality of fish. That plan sets forth, for the St. Lawrence River, the release of Walleye measuring less than 37 cm and more than 53 cm for sport and commercial fishing in order to protect recruits and spawners.

In short, certain species of fish show encouraging signs of re-establishment, suggesting that key pressures have lessened over time. Fish communities in the St. Lawrence, however, remain very fragile. In some sectors of the St. Lawrence, particularly in Lake Saint-Pierre, there are numerous indicators of deterioration of the ecosystem, and the situation has become critical for some species of fish. Major challenges thus remain to ensure that fish in the St. Lawrence have a healthy environment, which will require the restoration of habitats in the flood plains and large areas of aquatic-grass beds, the improvement of water quality, and the improvement of connectivity between habitats.

Long Description

A map is shown of the wetlands on Boucherville Islands; the background is a satellite image and the various types of wetlands are illustrated on it using different colours: light blue represents shallow water, mauve corresponds to low marshes, yellow represents high marshes and green corresponds to treed swamps. The pie charts in the figure show the four elements used to characterize the state of the wetlands, i.e. protection of wetland functions, anthropogenic pressure on them, internal dynamics and the diversity of habitats. For the Boucherville Islands, the findings regarding the state of these four elements are respectively good (green), good (green), moderate (yellow) and moderate (yellow). The trends are good (green), moderate (yellow), poor (red) and moderate (yellow). The overall finding associated with the indicator is moderate-good.

The indicator for size of freshwater wetland areas was modified to incorporate four aspects: direct anthropogenic pressures on coverage, the internal dynamic of the wetlands, the diversity of wet habitats, and the protection of wetlands against external stressors. The sectors of the Boucherville islands and Lake Saint-Pierre were examined. The general state of the wetlands in those sectors is qualified as moderate-good, and the general trend is stable.

Long Description

A map is shown of the wetland gains and losses in Lake Saint-Pierre; the background is a satellite image and the various types of gains and losses are illustrated on it using different colours: light green represents wetland gains in open water, dark green corresponds to perennial wetland gains in open water, pink represents wetland losses to open water and red corresponds to wetland losses due to anthropogenic activity. The pie charts in the figure show the four elements used to characterize the state of the wetlands, i.e., protection of wetland functions, anthropogenic pressure on them, internal dynamics and the diversity of habitats. For Lake Saint-Pierre, the findings regarding the state of these four elements are respectively poor (red), good (green), good (green) and good (green). The trends are moderate, stable, stable, and stable (all characterized by the colour yellow).

Direct anthropogenic pressures on wetlands are estimated using the net gains and losses in size. Between 2002 and 2010, no net loss of wetland area caused by direct human activities was noted in the area of the Boucherville Islands. The net gains and losses are therefore nil and are primarily due to the park status conferred on this sector. A difference in area has been observed, but this is the result of a drop in water levels between the two dates. Regarding Lake Saint-Pierre, there was a net increase of 64 ha of wetlands between 2002 and 2010. This is explained by the appearance of 101 ha of wetlands, minus 37 ha of wetlands that were lost to agriculture. For the period between 1990 and 2002, the trend is stable in the Boucherville Islands, as no additional losses or gains were observed. However, the fact remains that the 55 ha lost during that period were not recovered. In Lake Saint-Pierre, the net gain observed does not compensate for the losses to agriculture totalling 789 ha observed between 1990 and 2002. The trend for this sector can also be qualified as stable.

The internal dynamic of the wetlands is characterized by the ratio between the total areas that became drier and the total areas that present wetter conditions (Jean and Létourneau 2011). Between 2002 and 2010, in the Boucherville Islands area, the wetlands that dried up total three times the area of those places that became wetter. The transition from low marsh to high marsh represents the most significant internal change to the wetlands. For Lake Saint-Pierre, again between 2002 and 2010, the wetland areas that had dried total less than twice those that had become wetter. Here again, the transition from low marsh to high marsh represents the most significant change observed. Since the end of the 1970s, three successive periods of drying have been observed. On the other hand, no periods of wetting were detected based on the data available. The trend is deemed to be of concern (poor). Since the end of the 1970s, in Lake Saint-Pierre, a period of moderate wetlands wetting was observed, followed by two periods of slight drying. In this case, the trend is to be monitored (moderate).

The diversity of wetlands is evaluated by calculating the relative proportion of the five classes of wetlands present along the St. Lawrence (shallow water or aquatic-grass beds, low marshes, high marshes, shrub swamps, treed swamps). The evaluation of the relative proportion of classes of wetlands in the Boucherville Islands gives a moderate rating. The high marshes represent more than half of the wetland area in this sector, while shrub swamps are absent. However, the relative proportion of classes of wetlands in Lake Saint-Pierre is deemed to be good. The five classes of wetlands are well represented in this area. Since 1990, the trend is stable in the Boucherville Islands even though an increased inequality of classes of wetlands. For Lake Saint-Pierre, during the same period, a slight increase was observed in the relative proportion of classes of wetlands was observed. This temporal trend, however, is deemed to be stable.

The protection of wetlands from external stressors is evaluated using the presence of a protective zone 50 m wide, consisting of natural soil environments on the borders of wetlands. This protective zone was present over 76% of the limits of the wetlands in the Boucherville Islands sector in 2010. This finding is good. The largest proportion of this protective area is herbaceous. In Lake Saint-Pierre, this wetland protective zone is only present over 26% of the perimeter of wetlands and consists almost entirely of upland forests. This poor rating is attributable to the omnipresence of agricultural areas in the immediate area of the wetlands. Since 1990, there has been an improvement in the protective zone in the Boucherville Islands sector, whereas the temporal trend for the protective zone in Lake Saint-Pierre is stable.

Long Description

The map shows the geographic location of sampling sites for invasive plant species in the fluvial section extending from Lake Saint-François to Lake Saint-Pierre and in the fluvial estuary, from 2008 to 2010. The colour green corresponds to an invasion indicator of nil or an absence of invasive plant species, yellow represents an invasion indicator of low, orange corresponds to an invasion indicator of moderate and red represents an invasion indicator of high. The sites are then grouped in pie charts by section of the river. Lake Saint-François: yellow (67%) and orange (33%); Lake Saint-Louis: green (10%), yellow (16%), orange (53%) and red (21%); Montréal-Sorel section: yellow (20%), orange (40%) and red (40%); Lake Saint-Pierre: yellow (11%), orange (66%) and red (23%); fluvial estuary: green (8%), yellow (33%), orange (46%) and red (13%). The overall finding associated with the indicator is moderate-poor.

The monitoring, in cooperation with communities, of alien invasive plant species in the wetlands of the St. Lawrence continued between 2008 and 2010. During that period, the Haut-Saint-Laurent, Jacques-Cartier, Lake Saint-Pierre and Deux Rives ZIP committees and the Société d’aménagement de la baie Lavallière visited close to 300 sites consisting of shallow water, high and low marshes, and shrub and treed swamps. The species monitored were the Reed Phalaris, the Flowering Rush, the European Frogbit, the Eurasian Water-milfoil, the Common Water Reed and the Purple Loosestrife.

The results obtained between 2008 and 2010 indicate that of all the sites visited, 246 were affected by the target species. Of those sites, 22% were highly invaded, 56% were moderately invaded and 19% were slightly invaded. The sectors most affected by alien invasive plant species are the sectors of Boucherville and Lake Saint-Pierre, while the sectors least affected are Lake Saint-François and the freshwater estuary. The dominant species observed are the Common Water Reed and the Reed Phalaris. Purple Loosestrife is the species most frequently observed in the wetlands studied. However, it is rarely dominant at the sites visited. Most of the time, it is slightly or moderately represented. All the sites will be visited again between 2012 and 2014. It will then be possible to identify a trend regarding the evolution of invasion of wetlands in the St. Lawrence between 2005 and 2014.

Long Description

We can see a cross-section of the river with various key indicators of the freshwater aquatic ecosystem regarding contamination by toxic substances based on the categories of water, sediments and biological resources, each indicator being represented by a symbol. The water element is represented by contamination of the water by toxics substances; sediments are represented by the toxic contamination of sediments indicator; biological resources are represented by the communities of benthic macroinvertebrates, by contamination of fish by toxic substances, and by the contamination of the Great Blue Heron by toxic substances. Arrows represent the biomagnifications of contaminants, which leave the shoreline (where a factory constitutes a potential source of contaminants) to move toward the water, then toward sediments, benthic macroinvertebrates and fish, to then be transferred to the top of the food chain, where we find the Great Blue Heron.

The presence of toxic contaminants in the aquatic ecosystem is an indicator of its disturbance and can be monitored through its various components, i.e, water, sediment and living organisms. In effect, certain contaminants, such as mercury and polychlorinated biphenyls (PCBs), are subject to bioaccumulation and biomagnification in the food chain, which can have significant negative impacts on living organisms. There are many sources of toxic contaminants: industrial waste, urban effluents, or runoff from farm land (pesticides). Contaminants can be transported in the water over very long distances depending on their solubility and physical factors such as flow. They are sometimes bound to particulates and settle in sediments where they can become trapped, where we see an accumulation of sediments, or remobilized where there is erosion and transport of sediment materials. Benthic organisms living on the interface of sediments can be affected by the presence of contaminants depending on their relative sensitivity and the concentrations of contaminants that are present. Benthic organisms serve as food for numerous other aquatic species, such as young fish, which can then be eaten by larger predators (fish, birds or mammals), and the toxic contaminants are thus transferred and biomagnified in the food chain.

Long Description

The map shows the geographic location of the sampling stations for contamination of the water by toxics substances. The first station is located at Wolfe Island (at the outlet of Lake Ontario), the second is at Carillon (on the Ottawa River) and the third is at Québec City. The colour green corresponds to concentrations of contaminants below the criteria for protecting aquatic life and to a state that is not of concern; yellow corresponds to concentrations of contaminants close to the criteria and to a state that is to be monitored; red represents concentrations that exceed the criteria and to a state that is of concern; and white is used for contaminants not measured at that station and therefore corresponding to an undetermined state. At each station, four groups of substances are represented: pharmaceuticals and personal care products (PPCPs), metals, pesticides and PBDEs. Wolfe Island station: PPCPs – white; metals – green; pesticides – green (upward trend); Carillon station: PPCPs – yellow; metals – green; pesticides – green; PBDEs – yellow; Québec City station: PPCPs – yellow; metals – green; pesticides – green (downward trend); PBDEs – red (upward trend). The sources of contaminants are also noted on the map using symbols. For pesticides: Lake Ontario (yellow) and Lake Saint-Pierre (red); for PPCPs and PBDEs: Montréal area (red); for metals: Montréal-Sorel section and fluvial estuary (green). The overall finding associated with the indicator is moderate.

The quantity of a contaminant released into an ecosystem has a direct influence on its concentration in the aquatic environment. Similarly, the origin of a contaminant determines in part the variations of its concentration in the aquatic environment. Metals are naturally present in watercourses. It is only when concentrations exceed a certain threshold that we can conclude that there was a significant contribution by human activities. Concentrations of metals in the St. Lawrence do not exceed the water quality criteria for protection of aquatic life. In general, concentrations of pesticides in the river are on the same scale as those measured at Wolfe Island, at the outlet of Lake Ontario. However, at the Québec station, higher concentrations are observed in the summer due to the spreading of pesticides on crops located in the St. Lawrence lowlands, particularly in the Lake Saint-Pierre basin. From 1995 to 2012, we saw a net decrease (around 50%) in the input of pesticides to the estuary. The same decrease was not observed in the Great Lakes, but was substantial in Quebec tributaries, suggesting that the decrease observed in the river at Québec is the result of the decrease in the tributaries. It must be noted, however, that this decrease is undoubtedly attributable to a change in the type of pesticide, as modern pesticides are effective in smaller quantities. The maximum concentrations of polybrominated diphenyl ethers (PBDEs) and pharmaceuticals and personal care products (PPCPs) are found downstream from the Montréal region. Since 1995, concentrations of PBDEs have increased considerably at the outlet of the river, at Québec. Although we cannot evaluate the trend for pharmaceutical products, the number and sometimes the concentrations (e.g., for hormones) are areas of concern.

Although the water in the St. Lawrence comes primarily from Lake Ontario, the same is not necessarily true for contaminants. In the St. Lawrence, it is the affinity of contaminants with suspended solids that will dictate, in large part, the source of contaminants. Thus, since Lake Ontario acts as a vast settling pond, contaminants associated with particulates will tend to remain in the lake in the form of sediments. In the St. Lawrence, suspended particles and the related contaminants (metals and PBDEs) are not from the Great Lakes, but instead from erosion, urban or industrial effluents, and the river’s tributaries. However, more soluble contaminants, such as pesticides, are, to a significant degree, from Lake Ontario, while pharmaceutical products are from urban effluents.

Long Description

The map shows the sampled areas of the river where there is still contamination by toxic substances in the sediments. The first level of information presents the areas of the river in green (areas with little contamination), yellow (contaminated areas) and red (highly contaminated areas). The information is then grouped by section of the river to illustrate, in pie charts, the proportion of areas with little or no contamination (green, not of concern), contaminated areas (yellow, to be monitored) and highly contaminated areas (red, of concern). Lake Saint-François: green (58%), yellow (25%) and red (17%). Contaminants that exceed criteria in this section are PCBs, dioxins, furans and mercury. Lake Saint-Louis: green (54%), yellow (16%) and red (30%). Contaminants that currently exceed criteria in this section are PCBs, dioxins, furans, mercury, metals and PAHs. Montréal-Sorel section: green (51%), yellow (8%) and red (41%). Contaminants that exceed criteria in this section are PCBs, dioxins, furans, mercury, metals, PAHs, PBDEs, TBT and siloxanes. Lake Saint-Pierre: green (91%), yellow (4%) and red (5%). Contaminants that exceed criteria in this section are mercury and PBDEs. Quebec City: green (55%), yellow (20%) and red (25%). Contaminants that exceed criteria in this section are metals, PAHs and PCBs. The overall finding associated with the indicator is moderate.

The areas of the river in green, yellow and red indicate areas where contamination is present at three levels (slightly contaminated, contaminated and highly contaminated). The non-contaminated zones are not illustrated on the map but are calculated in the pie charts. Contaminants in the boxes are those that exceed the criteria in each section of the river.

The indicator for monitoring the quality of sediments aims to regularly record changes in the levels of their contamination in the St. Lawrence River. It allows us to report on the presence of various toxic substances and identify long-term trends. Data gathered over the last few years show a substantial decrease in the concentration of contaminants left behind by industrialization in the mid-20th century, also known as historical contaminants (see the Issues and perspectives section), such as PCBs, metals, polycyclic aromatic hydrocarbons (PAHs), mercury, dioxins and furans. Recent results identify new sources of contamination for old and new organic substances that may be harmful to the aquatic ecosystem, such as PBDEs, siloxanes, and tributyltin (TBT).

The creation of industrial and urban rehabilitation programs and numerous mitigation measures for sources of contamination has had noticeable and fast repercussions on the concentrations of toxic contaminants in sediments. Thirty years ago, all sediments in the fluvial lakes were contaminated by metals, mercury, PCBs and PAHs. Today, these contaminants do not represent a real threat, except in certain sectors, such as upstream from Lake Saint-François, the southern part of Lake Saint-Louis, the sector downstream from Montréal, the Sorel delta, Lake Saint-Pierre, and the ports of Montréal and Québec. Finally, recent work shows an increase in the concentrations of new substances, such as flame retardants (PDBEs), and the presence of emerging substances from urban effluents, such as siloxanes.

Long Description

The map shows the findings regarding the contamination of fish in three sectors of the river: Lake Saint-François, Lake Saint-Louis and Lake Saint-Pierre. The results are presented as pie charts showing the state of contamination of various species of fish by various contaminants. The colour green corresponds to contamination below the criteria for protection and to a state not of concern, yellow represents contamination close to the criteria and a state to be monitored, and red corresponds to contamination that exceeds the criteria and a state that is of concern. Lake Saint-François: contamination by mercury in Northern Pike (green), contamination by PBDEs in Northern Pike (green), contamination by PCBs in White Suckers (green), contamination by PBDEs in White Suckers (green), contamination by mercury in Walleyes (green) and contamination by PBDEs in Walleyes (green). Lake Saint-Louis: contamination by mercury in Northern Pike (red), contamination by PBDEs in Northern Pike (green), contamination by PCBs in White Suckers (green), contamination by PBDEs in White Suckers (green), contamination by mercury in Walleyes (yellow, downward trend) and contamination by PBDEs in Walleyes (green). Lake Saint-Pierre: contamination by mercury in Northern Pike (green, downward trend), contamination by PBDEs in Northern Pike (green), contamination by PCBs in White Suckers (yellow), contamination by PBDEs in White Suckers (yellow), contamination by mercury in Walleyes (green) and contamination by PBDEs in Walleyes (green). The overall finding associated with the indicator is moderate.

The indicator for contamination of fish more specifically examines three species: the Walleye, the Northern Pike and the White Sucker, in the river’s three fluvial lakes. The average concentrations of mercury (Hg) in Walleye are less than the Health Canada directive of 0.5 mg/kg at the 3 sites, but concentrations at Lake Saint-Louis are very close to the criteria, despite a decrease since the last findings in 2008. Since then the average concentrations of mercury in Northern Pike are lower than the Health Canada directive of 0.5 mg/ kg in Lake Saint-François and Lake Saint-Pierre but exceed the directive in Lake Saint-Louis. Mercury concentrations in Northern Eel are lower in 2011 in Lake Saint-Pierre. PCB concentrations in whole White Suckers measured in 2009 and 2011 do not differ much from those measures in the past in lakes Saint-François, Saint-Louis and Saint-Pierre. Average concentrations of PCB in whole White Suckers are higher in Lake Saint-Pierre than in Lake Saint-François. The average PCB levels in white suckers are below the criteria for fish-eating wildlife in lakes St. Francis and St. Louis but slightly higher in Lake Saint-Pierre. PBDE concentrations in the flesh of Walleyes and Northern Pikes in the three lakes are below the criteria for piscivorous wildlife (44 g/kg and 13 g/kg for tetra-BDEs and penta-BDEs respectively). In whole White Suckers, PBDE concentrations are below the criteria for piscivorous wildlife in lakes Saint François and Saint-Louis, but are very close to the criterion for Lake Saint-Pierre.

Long Description

The map shows the data regarding contamination of the Great Blue Heron at two stations in the fluvial section: Île aux Hérons and Grande Island. The following contaminants were examined in eggs: PCBs, PBDEs, TCDD, DDE and Hg. The colour green corresponds to contamination below the criteria for protection, i.e. a state not of concern, yellow represents contamination close to the criteria and a state to be monitored, and red corresponds to contamination that exceeds the criteria and a state that is of concern. Île aux Hérons: PCBs (green), PBDEs (yellow), TCDD (green), DDE (green) and Hg (green). Grande Island: PCBs (green), PBDEs (yellow), TCDD (green), DDE (green) and Hg (green). Two graphs also show the comparison of concentrations of contaminants in the eggs of the Great Blue Heron between historical and recent values. Île aux Hérons: mercury (1991–2011, significant decrease), PCBs (1991–2011, significant decrease), DDE (1991–2011, significant decrease), ET-TCDD (2001–2006, slight decrease) and PBDEs (2001–2011, significant decrease). Grande Island: mercury (1991–2011, slight decrease), PCBs (1991–2011, significant decrease), DDE (1991–2011, significant decrease), ET-TCDD (1991–2006, slight decrease) and PBDEs (2001–2011, significant decrease). The overall finding associated with the indicator is moderate-good.

The most recent concentrations of mercury, PCBs, DDEs, ET-TCDD and PBDEs were compared with historical data (histograms) and to toxicity criteria or thresholds taken from scientific literature (pie charts). These five contaminants or groups of contaminants are the most abundant and of most concern in the eggs of the Great Blue Heron. These contaminants all decreased since monitoring started, both at Île aux Hérons and at Grande Island. The average decrease is 62% (36% to 94%) at Île aux Hérons and 66% (33% to 97%) at Grande Island. The pie charts on the map indicate that concentrations of all the contaminants except penta-BDE are lower than the criteria in the two colonies.

In general, in the fluvial corridor, contamination indicators all show a decrease in historical contaminants (metals PCBs, DDTs). We no longer see these substances exceed the criteria for protecting aquatic life in water and very little in sediments and living organisms. Most trends are downward. The finding is different for emerging contaminants. For instance, contamination by PBDEs sometimes exceeds the criteria, and we have seen an increase in concentrations in water and sediments over the last decade.

Long Description

We can see a cross-section of the river with the various key indicators of the saltwater aquatic ecosystem based on the categories of water and biological resources, each indicator being represented by a symbol. The water element is represented by oceanographic processes and the quality of the shellfish waters; biological resources are represented by the contamination of the Great Blue Heron, seabirds, the Northern Gannet, the Beluga Whale, phytoplankton, zooplankton, toxic algae and the Striped Bass.

Long Description

The map shows the various sectors of the marine zone where the quality of shellfish water is measured. The pie charts show the proportions of the various classes of recommended classification of sectors based on water quality monitoring. The colour green corresponds to a recommendation for an approved sector, yellow is associated with a recommendation for a conditionally approved sector and red corresponds to a recommendation for a restricted and prohibited sector. Upper North Shore and Charlevoix: green (38%), yellow (14%) and red (48%). Middle North Shore: green (50%), yellow (2%) and red (48%). Lower North Shore: green (65%) and red (35%). Lower St. Lawrence: green (14%), yellow (4%) and red (82%). Gaspé Peninsula: green (18%), yellow (13%) and red (69%). Magdalen Islands: green (77%), yellow (5%) and red (18%). The overall finding associated with the indicator is moderate-good.

Overall, for all the portions of shoreline evaluated, the quality of water is moderate-good. In the Magdalen Islands, more than three quarters of the sectors evaluated meet the criteria for an approved or conditionally approved sector, and most of those meet the criteria for an approved sector. The quality of water is therefore excellent. On the Lower North Shore, close to two thirds of the sectors evaluated meet the criteria for an approved sector. This region has a large proportion of coast not defined in sectors, but where the anticipated quality of water appears to be excellent, given the absence of nearby sources of contamination. Overall, the quality of the water in this region is excellent. In the regions of the Upper North Shore/Charlevoix and Middle North Shore, about half of the sectors evaluated meet the criteria for an approved or conditionally approved sector, and the other half of the sectors do not meet those criteria and are prohibited from gathering shellfish. In the Gaspé Peninsula, about a third of the sectors evaluated meet the criteria for an approved or conditionally approved sector. Two thirds of the sectors evaluated do not meet these two criteria. In the Lower St. Lawrence, more than three quarters of the sectors evaluated do not meet the criteria for an approved or conditionally approved sector, and are prohibited from gathering shellfish.

The coastal waters are highly vulnerable to the impact of human activities, and we saw the same trend in 2013 as in 2008. Anthropogenic bacterial contamination is still causing the loss of use, such as gathering softshell clams and mussels. This problem remains more serious in the Gaspé Peninsula and the Lower St. Lawrence than in the Magdalen Islands and along the North Shore. As in the fluvial portion, it is wastewater from municipalities or remote residences and the presence of agricultural activity that are the main sources of bacteriological contamination. Little variation in water quality was measured for the priority shellfish sectors between 2008 and 2013, and none of the 53 priority sectors was reopened during that period. However, there were improvements regarding the sources of contamination in certain sectors in the Gaspé Peninsula and the Upper North Shore. Water quality has probably improved in two sectors of the North Shore following the construction and commissioning of a wastewater treatment plant (secondary treatment) in Portneuf-sur-Mer in 2011. In Gaspé Bay, ongoing efforts have been made to improve the existing wastewater treatment plant. Over the long term, an improvement could be seen in water quality with the implementation of the Wastewater Systems Effluent Regulations under the Fisheries Act, which favours the implementation and improvement of wastewater treatment plants.

Long Description

The map shows the findings related to the Striped Bass indicator. The four elements used to characterize the state are distribution, abundance, reproduction and growth. The colour green represents a population health indicator of good and not of concern, yellow corresponds to a moderate state to be monitored, and red represents a poor state that is of concern. The results: distribution – green; abundance – yellow; reproduction – yellow; growth – green. The points on the map show the sampling sites where the presence of the Striped Bass was confirmed, based on three categories of abundance: low, moderate and high. Two sites present a high abundance: a first reproduction site was located in 2011 at the mouth of the Rivière du Sud at Montmagny, and another reproduction site was then located in 2013 at the mouth of the Ouelle River at Rivière-Ouelle. The overall finding associated with the indicator is moderate-good.

Historically, the Striped Bass was primarily present between Lake Saint-Pierre and Kamouraska. Currently, following efforts to reintroduce the species, we note the presence of Striped Bass in the entire river, between Montréal and Rimouski (Figure 22). The Striped Bass that currently make up the population in the St. Lawrence are growing more rapidly than those of the former population. It seems that the food and fluvial rearing habitats in the St. Lawrence River are not limiting for the current level of abundance of the new population of Striped Bass. The capture of young of the year in 2008, when no seeding at that stage of development had been carried out in the river, confirmed the presence of natural reproduction. This observation was followed by the location in 2011 of a first breeding site at the mouth of the Rivière du Sud at Montmagny, followed by the location of a second breeding site in 2013 at the mouth of the Ouelle River at Rivière Ouelle (Figure 23). Since 2010, there has been an exponential increase in the abundance of juveniles. However, they are concentrated in a few areas, and their abundance remains low. The distribution area is larger than it was in the past and is probably related to the exploratory behaviour of a species that is settling into a new environment. The abundance of the Striped Bass in the St. Lawrence River has considerably increased since the last finding, although it remains low. Maintenance of this new population remains precarious. The state of the indicators used does not yet allow for sampling or sustainable use of the resource.

Long Description

The map shows spots where natural reproduction of the Striped Bass was observed in saltwater. It presents the location of a first reproduction site, at the mouth of the Rivière du Sud at Montmagny, where the presence of adult Striped Bass and reproductive activity were observed, and that of a second reproduction site at the mouth of the Ouelle River at Rivière-Ouelle. The presence of young of the year was observed at numerous sites. A graph showing the number of juvenile Striped Bass per 1000 metres of eel canvas based on time (2004–2012). 2004: 0; 2005: 0.2; 2006: 5; 2007: 3.7; 2008: 3.6; 2009: 3.5; 2010: 265.4; 2011: 898.5; 2012: 1,176.3.

Long Description

The map shows the findings related to the Northern Gannet and seabirds indicators. In the case of the Northern Gannet, the elements used to characterize the state of the population are abundance, reproductive success and contamination of eggs. For seabirds, the populations evaluated are Herring Gulls, Caspian Terns, Common Murres, Razorbills and Atlantic Puffins. The colour green represents a population health indicator of good and not of concern, yellow corresponds to a moderate state to be monitored, and red represents a poor state that is of concern. Northern Gannet: abundance – yellow (downward trend); reproductive success – red (downward trend); contamination – green (downward trend). Seabirds: Herring Gull – green (stable trend); Caspian Tern – red (stable trend); Common Murre – green (upward trend); Razorbill – green (upward trend); Atlantic Puffin – red (downward trend). The overall finding associated with the Northern Gannet indicator is moderate-poor and the overall finding associated with the seabirds indicator is moderate.

Seabirds
Using 2005 and 2010 inventories, while taking into consideration the five-year inventory data collected since 1925, the most recent trends were analyzed for the populations of each species in the sanctuaries. The Herring Gull population has remained stable; the Caspian Tern is still present, but again with only three individuals; the number of Common Murres increased significantly between 2005 and 2010 (+77%), and the population is currently at a fairly high level. There was another impressive increase in the Razorbill population in the sanctuaries between 2005 and 2010 (+61%), and that growth has been almost steady since 1977. The Atlantic Puffin declined moderately (-15%) between the last two inventories, but that is the third consecutive drop in its numbers, giving a decline of 54% since 1993, such that the estimated population in 2010 was the second-smallest since 1925.

In the previous overview (following the 2005 inventory), it was found that the population of Herring Gulls in the refuges had stabilized after 1993, and that finding did not change in 2010. Three Caspian Terns were found in 2005, while the species was absent in the two previous inventories. This reappearance is encouraging, but the status of the species remains worrisome. Without population growth, the status of the species remains excessively precarious. Following a worrisome decline of 51% between the years 1998 to 1999 and 2005, the number of Common Murres rebounded in 2010 to a high level, close to the maximums of 1993 and 1998 to 1999. The finding for this species therefore changed from to-be-monitored in 2005 to good in 2010. The steady growth in the population of Razorbills since 1977 explains why the good finding remained the same in 2005 and 2010. With this third consecutive decrease in the number of Atlantic Puffins in the sanctuaries, the population trend appears to be strongly downward, and its population level is increasingly low, which explains why the finding went from moderate (in 2005) to poor (in 2010).

Northern Gannet
The size of the population is large and only 13% lower than the maximum recorded in 2009, but the signs of decline after 2009 follow a long period (approximately 30 years) of population growth. Reproductive success has been declining at a worrisome rate since 2009 and is currently too low to maintain the colony. Supplementary studies have shown that the birds seem to be having trouble finding their food and must travel very far from their colony to feed, which would affect their reproductive success.

In the previous finding, the three indicators were increasing, and the situation was very positive. Since then, however, although the levels of contaminants have continued to drop in general, reproductive success has dropped sharply to reach the lowest levels ever observed on Bonaventure Island in 2011 and 2012. Such low reproductive success can only result in a decline of the reproductive population over the long term (with a delay of five or six years, the age at which birds begin to reproduce). After 2009, the growth of the population stopped, with the size of the two main colonies showing variations edging toward decline. Countering this trend would require that the reproductive success climb back up to 67% (percentage of young born in a particular year and that survive to first flight).

Long Description

The map shows the findings associated with the Beluga Whale indicator in the zone being studied, which is in the lower estuary and the Saguenay Fjord. The elements used to characterize the health of the population are abundance, proportion of 0-1-year-olds, the mortality rate and contamination. The colour green represents a good state not of concern, yellow corresponds to a moderate state to be monitored, and red represents a poor state that is of concern. State: abundance – red (downward trend); proportion of 0-1-year-olds – red (downward trend); mortality – yellow (upward trend); contamination – yellow (downward trend). A graph also presents the estimated size of the Beluga Whale population in the St. Lawrence estuary: abundance fell from 8000 individuals in 1920 to 1000 in the 1950s. A recent drop was observed in 2002 and the population fell to 889 individuals in 2012. The overall finding associated with the indicator is poor.

Integrating data up to 2012, the model used to monitor the Beluga Whale population in the St. Lawrence estimates that the population was stable or increasing slightly from the end of hunting in the 1960s until the early part of the 2000s, reaching approximately 1000 individuals in 2002, then declined since that time to 889 individuals (IC 95%: 672-1,167) in 2012. Again according to the model, changes in vital parameters and in age structure seem to have occurred in the Beluga Whale population in the St. Lawrence estuary. We are therefore seeing a transition from a period of relative stability in vital parameters prior to 1998, characterized by cycles of three-year intervals between maximums in reproduction, to a period of instability characterized by a two-year reproductive cycle, resulting from increased variability in mortality rates among newborns and gestation rates and a decline in the proportion of newborns and immature births in the population. Beluga Whales are exposed to noise and disruption from maritime traffic, recreational activities and the whale-watching industry. An analysis of 28 indicators describing the ecosystem showed that conditions have changed in the Gulf of St. Lawrence since the end of the 1990s. Analysis of chemical markers in Beluga Whale carcasses from 1988 to 2012 indicates a change in the sources of carbon (probably related to diet) used by adult males and females since 2003. An unusually high number of Beluga Whale carcasses found in 2008, including 8 newborns and a range of other species, coincided with a proliferation of the dinoflagellate Alexandrium tamarense, which produces paralyzing toxins (saxitoxins), and it has been shown that several dead animals had been exposed to saxitoxins. The number of carcasses of newborns in 2010 and 2012 was 8 and 16 times higher than the median number observed since 1983 and was likely the result of a combination of an increase in the production of young and a decrease in the survival of those young. This mortality occurred during a period of long-term below-average icy conditions and higher water temperatures in 2012.

Long Description

A graph shows the temporal trend in PBDE contamination among male Belugas (blue) and female Belugas (red). The vertical lines represent the standard deviation and significative trends are identified by the line segments. Between 1990 and 2000, PBDE concentrations rose among males and females, from 3-4 ng/g of PBDE in the lipids to approximately 6 ng/g. PBDE concentrations continued to rise among male adults (6.5 ng/g) in 2007), but the rate of increase has fallen since the 2000s (the series ended in 2008). Among adult females and newborn, PBDE concentrations have not increased since the end of the 2000s (the series ending in 2012 for both groups).

Long Description

A graph shows the comparison of concentrations of contaminants in the eggs of Northern Gannets between historical and recent values. Mercury (1969–2009): significant decrease; PCBs (1969–2009): significant decrease; DDE (1969–2009): significant decrease; ET-TCDD (2004–2009): increase; PBDE (2004–2009): significant decrease.

Long Description

The map shows the contamination of the Great Blue Heron at two saltwater stations: Île aux Basques and Manowin Island. The following contaminants were examined in eggs: PCBs, PBDEs, TCDD, DDE and Hg. The colour green corresponds to contamination below the criteria for protection, i.e., a state not of concern, yellow represents contamination close to the criteria and to be monitored, and red corresponds to contamination that exceeds the criteria and a state that is of concern. Île aux Basques: PCBs – green; PBDEs – yellow; TCDD – green; DDE – green; Hg – green; Manowin Island: PCBs – green; PBDEs – green; TCDD – green; DDE – green; Hg – green. Two graphs also show the comparison of concentrations of contaminants in the eggs of Great Blue Herons between historical and recent values. Île aux Basques: mercury (1992–2011) – significant decrease; PCBs (1992–2011) – significant decrease; DDE (1992–2011) – significant decrease); ET-TCDD (2002–2007) – increase; and PBDEs (2002–2011) – significant decrease. Manowin Island: mercury (1992–2011) – significant decrease; PCBs (1992–2011) – significant decrease; DDE (1992–2011) – significant decrease; ET-TCDD (2007) – significant decrease; and PBDEs (2007–2011) – significant decrease. The overall finding associated with the indicator is moderate-good.

The most recent concentrations of mercury, PCBs, DDE, ET-TCDD and PBDEs were compared with historical data (histograms) and with toxicity criteria or thresholds taken from scientific literature (pie charts). These contaminants have all decreased in the two colonies since monitoring started, except ET-TCDD on Île aux Basques. The average decrease is 32% (-68% to 86%) at Île aux Basques and 55% (34% to 72%) at Manowin Island. The concentrations of all contaminants are below the criteria at both colonies, except penta-BDE on Île aux Basques. For dioxins, despite an increase compared to 2002 at Île aux Basques, concentrations have remained below the criterion value.

Like the fluvial corridor, indicators of contamination in the estuary and the Gulf all show a decrease in historical contaminants (metals, PCBs, DDT). ET-TCDD, although in concentrations below the criterion, is higher in the eggs of the Northern Gannet than in the eggs of the Great Blue Heron in the fluvial corridor. With regard to emerging contaminants, PBDEs have increased among the Beluga Whale and decreased among birds, although penta-BDE exceeds the criterion at Île aux Basques.

Long Description

The figure shows a gradient of increase in the supply of nutrients and the result in the aquatic ecosystem. When there are very few nutrients, the environment is characterized as oligotrophic, a lot of light is available, and the biomass is low in terms of plankton, periphyton, aquatic plants, macroinvertebrates and fish. The next stage, referred to as mesotrophic, is characterized by clear water and numerous aquatic plants. When the supply of nutrients increases significantly, the environment become eutrophic, the biomass decreases in terms of plants, macroinvertebrates and fish, but we also see an increase in the presence of filamentous algae, first attached to plants, then floating on the surface. The final stage, referred to as hypereutrophic, is characterized by turbid water and a high level of biomass and phytoplankton, including cyanobacteria, whereas plants, macroinvertebrates and fish are almost absent.

Submerged aquatic plants constitute a major element of the fish habitat, providing them with shelter from predators and physical support for the algae and invertebrates that they eat. In their original state, shallow environments support low biomasses of algae and submerged plants (Figure 29). Enrichment by nutrients promotes the growth of aquatic vegetation and increases biological productivity, which increases the capacity to support fish habitats. However, beyond a certain critical threshold, excessive enrichment and turbidity in the water hampers the growth of submerged vegetation, thus causing a deterioration of the fish habitat. The passage of the enriched water of the Yamaska and Saint-François rivers through dense vegetation at the mouth of the rivers in Lake Saint-Pierre illustrates the link between nutrients, aquatic plants, invertebrates and fish along the south shore of Lake Saint-Pierre (Hudon et al. 2012). After the water from the tributaries goes through the vegetation, several phenomena occur:

• The dissolved nitrogen/phosphorous ratio is unbalanced, and the organic nitrogen disappears.
• This change induces a decrease and the eventual disappearance of macrophytes, filamentous algae and epiphytes.
• These nutrient conditions and the disappearance of competitors foster the development of benthic cyanobacteria.

Carpets of cyanobacteria represent a habitat that is less complex and less rich in prey for fish, which results in a decrease in growth and survival among young Yellow Perch and in the number of adult fish species. Prior to this change, the area thus affected represented a vast area of reproduction, fry rearing, shelter and growth for a wide range of fish species. The presence of Lyngbia wollei and Gleotrichia pisum (two cyanobacteria) can therefore serve as an indicator of the effect of eutrophication on the aquatic ecosystem of the St. Lawrence.

Yellow Perch in Lake Saint-Pierre saw a major decline as of the mid-1990s. The situation became so critical that, in 2012, the Government of Québec decreed a five-year moratorium on commercial and sport fishing. A recent study of the situation (De la Chenelière et al. 2014) found that, although fishing contributed to the collapse, Yellow Perch also suffered from the deterioration of its habitats since the 1950s. The analysis of land use based on aerial photography, combined with modelling of the best reproduction habitats in the littoral zone, indicates that 5000 ha of spring habitats were altered in a negative manner by a number of anthropogenic activities, primarily agricultural. The disappearance of vegetation and the proliferation of benthic cyanobacteria in the growth areas of young Yellow Perch, the decrease in the connectivity between the lake and the littoral zone, the climate, the introduction of competitive alien species and the introduction of a new avian predator (cormorant) have contributed to the failure in recruitment and the decline in Yellow Perch. Findings regarding the deterioration of Lake Saint-Pierre indicate that the situation will only improve once the species are able to reproduce and develop in a healthy environment, which will require the restoration of habitats and the improvement of water quality and connectivity between the lake and the littoral zone to allow for the partial or total recovery of the environment's historical capacity for support. The precarious state of the Yellow Perch, an important link in the aquatic communities of Lake Saint-Pierre, must be interpreted as one of many indicators of the deterioration of this exceptional ecosystem.

Long Description

We can see a cross-section of the river with the various key indicators of the freshwater aquatic ecosystem related to contamination by toxic substances, each indicator being represented by a symbol. The diagram is separated in two parts: one represents historical contamination, including contamination by metals such as mercury, and the other represents emerging contamination, including contamination by PBDEs. Contamination by toxic substances is observed in the water, sediments, fish and the Great Blue Heron. Arrows represent the biomagnifications of contaminants, which leave the shoreline (where a factory constitutes a potential source of contaminants) to move toward the water, then toward sediments, fish, to then be transferred to the top of the food chain, where we find the Great Blue Heron. For historical contamination by mercury, we no longer see that substance exceed the criteria for protecting aquatic life in water and very little in sediments and living organisms. Most trends are downward (water: good state, stable trend; sediment: moderate state, downward trend; fish: moderate state, downward trend; Great Blue Heron: good state, downward trend). Conversely, emerging contamination, such as by PBDEs, often exceeds criteria for aquatic life and we have seen an increase in concentrations over the last decade (water: poor state, upward trend; sediments: poor state, upward trend; fish: moderate state, stable trend; Great Blue Heron: moderate state, downward trend).

Regarding contamination by toxic substances in the St. Lawrence, we can see two groups of substances: historical contamination, i.e., that left by the industrial revolution, and emerging contamination, which is progressing and corresponds more to a sign of recent urban and industrial development. Historical contamination corresponds to metals, such as mercury, and other contaminants, such as organochlorine pesticides and PCBs. Emerging contamination consists of numerous groups of substances, such as PBDEs and PPCPs. PBDEs are fire retardants that have been used in polyurethane foam, electronic products, textiles and plastics since the 1970s. PPCPs include medications (hormones, antidepressants, etc.) and hygiene and beauty products. Although these products have been present in the environment for a long time, the development of analytical methods sensitive enough to detect them is more recent. When these two groups of substances are observed separately, we see different findings regarding their state and the trends observed in the environment. For historical contamination, we no longer see these substances exceed the criteria for protecting aquatic life in water and very little in sediments and living organisms, and most trends are downward. On the other hand, emerging contamination, such as PBDEs, often exceeds the criteria for aquatic life, and we have seen an increase in concentrations over the last decade. It may be relevant to consider these groups of substances separately in the various indicators for contamination in order to not dilute the findings and obtain an average or moderate mark regarding the overall finding for them.

Some PDBEs have potential for bioaccumulation and may cause harmful effects in animals. Since the 1990s, various measures have been taken, including voluntary withdrawal of certain products by manufacturers and restrictions in Canada and other countries, and reductions have been observed in environmental concentrations, particularly in the eggs of the Great Blue Heron and the Northern Gannet in the Gulf and the St. Lawrence River. Those restrictions, however, have resulted in an increase in the use of alternative fire retardants, which are also in the ecosystem and the potential effects of which are not known. A number of these products, such as hexabromocyclododecane (HBCDD), polybrominated biphenyl (PBBS), hexabromobenzene (HBB) and decabromodiphenyl ethane (DBDPE), are now commonly measured in scientific studies and certain monitoring programs. Once in the environment, several products degrade under the effect of factors such as light or are metabolized by organisms, thus forming new products that can also be measured. For instance, hydroxylated PCBs (OH-PCBs) and methylsulfonyl PCBs (MeSO²-PCBs), products of the degradation of PCBs, are found in the tissue of birds. These products are just a few examples of emerging contaminants that could be measured as part of the monitoring program over the coming years.