Global Issues On The State Of The St. Lawrence: Discussion sessions

Deoxygenation and Acidification of the Deep Waters in the Gulf of St. Lawrence

Facilitator: Serge Hébert, Ministère du Développement durable, de l’Environnement, de la Faune et des Parcs; Secretary: Céline Schaldembrand, Stratégies Saint-Laurent

Dams have brought an end to major floods; they therefore have an impact. It is reasonable to assume that there is a cumulative effect from all the dams. However, dams have only a local impact when it comes to water oxygenation. Surface water reoxygenation through exchanges with the atmosphere takes place over a fairly short time span (two weeks), which is not the case with carbon dioxide (much slower).

Picture of the discussion table on deoxygenation

A meaningful indicator for the St. Lawrence's hypoxia that would be simple to compile would be based on the concentration of oxygen and temperature at a depth of 300 m in the lower estuary. This index would be measured using sensors and chemical titration.

Are there modifications or solutions that can be used to combat deoxygenation?

Whereas in the Baltic Sea, for example, the water is aerated to evaporate the sulfuric acid, there is no such solution in Canada. However, a key approach would be to implement actions to not only address climate change but also to reduce nutrient inputs and study the cumulative effects of harnessing rivers.

Climate change is giving rise to significant alterations, including ones to the major ocean currents that enter the gulf. However, the mix ratio of water from the Labrador Current and Gulf Stream tends to change. This change has a significant effect on hypoxia, as the higher proportion of water from the Gulf Stream is more poorly oxygenated.

Does the quantity of anthropogenic nutrients play a role in hypoxia?

An important thesis is being prepared, and results on this subject are coming. However, anthropogenic nutrients can be considered to have a rather low impact on hypoxia but that, relatively speaking, nitrites and nitrates are still interesting anyway, as their role is by no means insignificant, especially when the critical threshold for hypoxia is reached. However, they do play an important role in toxic algal blooms and promote, for example, flagellates.

Would it be worthwhile to determine the quantity of anthropogenic nutrients entering certain parts of the St. Lawrence?

It would be even more important to know the nitrogen/phosphorus (N/P) ratio and the nitrogen/silica (N/Si) ratios, as they are indicators of ecosystem change. However, Year 1 does not yet exist. The nitrogen/phosphorous (N/P) ratio could be regarded as an unexpected result.

There is a direct/linear relationship between water temperature and toxic algae. In the cases examined, it is easier to identify factors because there is longer-term data. Benthos monitoring could be a good indicator, even if there is very little monitoring -- just ad hoc studies.

Which species are likely to be favoured or hindered by a decrease in oxygen? How will the ecosystem be affected?

Studies have been conducted, particularly on the Northern Shrimp and the Greenland Halibut (or Black Turbot). For the latter species, an oxygen level becomes problematic above 15% saturation.

If I had to draw up a wish list, mooring and measuring the oxygen in the ocean (and not just salinity and temperature measurements) would be on it. Many effective methods are too onerous to be used on a large scale. For a number of important aspects that could be used as indicators (e.g. benthos), there is a lack of monitoring programs and access only to ad hoc studies.

Impacts of Climate Change on Hydrologic Inputs of the Great Lakes and St. Lawrence River Watersheds

Facilitator: Martin Jean, Environment Canada; Secretary: Caroline Girard, Environment Canada

From the outset, the participants agreed that the issue of climate change was critical in accurately determining the state of the St. Lawrence. They also agreed that it was difficult to develop an indicator based on this issue, particularly given the uncertainties surrounding the measurement and prediction of climate-related changes. Climate prediction models are not yet well developed, so it is still difficult to accurately predict the impacts of these changes.

Picture of the discussion table on climate change

Various concerns about climate change in the St. Lawrence were raised: the movement of the estuarine salinity front and impacts on drinking water intakes; the variable range of low-water periods and impacts on water quality (overflows, emergence of contaminated sediments, etc.); and the reliability of climate change prediction models.

Participants identified more specific needs regarding climate change information. In particular, municipalities require information that would make it possible to better manage the risks of degradation of water management infrastructure, natural environments and navigation infrastructure. Better knowledge of future changes would therefore increase the chances of adapting and limiting losses over the short and long terms.

These are a few points to consider when climate change indicators are determined through the State of the St. Lawrence Monitoring Program:


  • Take climate change into account when analyzing the existing indicators of the State of the St. Lawrence Monitoring Program. This could mean establishing a shared pool of climate change information in order to analyze each indicator consistently. It would therefore be worthwhile to develop climate change scenarios with components on the direction, scope and dispersion of climate-related changes that would enhance the existing indicators of the state of the St. Lawrence.

  • Develop new prediction tools (or use existing indicators) to add an estimate of future climate change and offer decision-makers tools for assessing infrastructure vulnerability and land use prospects (e.g. intensity and frequency curves for extreme weather events such as precipitation).

  • Include economic indicators to assess the state of the ecosystem in relation to climate change (e.g. the economic impacts of water-level variations at the Port of Montreal).

12 Years of Monitoring Emerging Contaminants: St. Lawrence Results and Perspectives & Identifying a New Generation of Flame Retardants in a St. Lawrence Seagull: Is the PBDE Saga Repeating Itself?

Facilitator: Louise Champoux, Environment Canada; Secretary: David Berryman, Ministère du Développement durable, de l'Environnement, de la Faune et des Parcs (MDDEFP)

Participants began by noting that it was troubling, even alarming, that all these products are present in aquatic environments, including the St. Lawrence. It is disconcerting to know that all organisms, including humans, are exposed to them. The discussion covered a number of points concerning emerging contaminants, but they did not all relate to the monitoring of these substances in the St. Lawrence.

Picture of the discussion table on emerging contaminants.

Some felt more information should be provided to the media on the issue of emerging contaminants to inform the public and prompt it to put pressure on political authorities. Participants are aware that governmental and academic specialists do not have equal freedom to do this.

Concern was expressed that, barring a few exceptions, there is no way of knowing what is in the consumer goods we buy. This prevents us from shifting our purchases to goods such as flame retardants free of harmful products.

Canada’s launch of an environmental study on the chemicals used in its territory was noted and applauded. This study has sped up government action on products deemed harmful such as nonylphenol ethoxylates, pentaBDEs and perfluorooctanesulfonate (PFOS). In addition to this government initiative, a reverse onus, as with Europe’s REACH regulation, is needed.

Participants were also displeased that the Maurice Lamontagne Institute’s ecotoxicology team had been disbanded. The result is an inability to determine the significance and extent of the emerging contaminant problem in the St. Lawrence marine ecosystem. For example, the ingestion of plastics by marine mammals and marine reptiles, a problem observed in many parts of the world, is not being studied in the St. Lawrence.

The complexity of monitoring emerging contaminants was noted, particularly because the ecosystem compartment to be sampled is not the same for all contaminants. Take, for example, decaBDE, which is found in Ring-billed Gulls, but only rarely in the eggs of the Great Blue Heron and Northern Gannet. According to some, there is not enough data on the presence of emerging contaminants in sediments, particularly in the marine environment.

It was noted that the United Nations and World Health Organization had recently published a joint report on endocrine disruptors. The report summarizes and describes the existing knowledge on this issue, adding weight to the evidence respecting both human health and the effects on other species. However, workshop participants pointed out that endocrine disruption problems in humans may stem from contaminants whose primary exposure routes are not drinking water. In the case of nonylphenol ethoxylates, polybrominated diphenyl ethers (PBDEs), perfluorinated compounds and medications, the MDDEFP‘s monitoring has confirmed that drinking water is not the primary route of human exposure. As one participant pointed out, "We will all die from a good many things before succumbing to the water quality of the St. Lawrence." The conclusions regarding the potential effects on other species are much less clear.

Some participants indicated that we have a lot more data on the presence of emerging contaminants in the St. Lawrence than on their effects. We have known for some time now that, downstream from Montréal, the Elliptio complanata mussel and the Spottail Shiner are exhibiting endocrine disruption problems. However, not many studies have been conducted to check for the problem among other species. We do not know the spatial extent of the problem or its magnitude in terms of the number of species affected.

Participants noted the importance of continuing to monitor emerging contaminants and their effects in the St. Lawrence River.

Collapse of the Yellow Perch in Lake Saint Pierre: How Did We Get There and What Can We Do About It?

Facilitator: Yves Paradis, Ministère du Développement durable, de l'Environnement, de la Faune et des Parcs (MDDEFP); Secretary: Élise Mercure, Stratégies Saint-Laurent

Summary of discussions from the session

Participants shared comments about two major areas of concern:

Picture of the discussion table on Yellow Perch


  1. The hydraulic changes to the river and its tributaries, which indirectly affect fish habitats along the shores of Lake Saint-Pierre: the effects of the shipping channel, reduction in ice jams, decrease in traffic along the shores, sediment accumulation downstream from the tributaries and dams in the tributaries.

  3. Reduced water quality and phosphorus enrichment of waters along the shores, particularly in relation to agricultural pollution.

The comments underscored that the ecosystem health indicators for Lake Saint-Pierre should:


  1. be simple, easily understood and easy to illustrate to the public (e.g. Yellow Perch catches);

  3. address the practical concerns of those who live in the region and not just scientists’ concerns (e.g. corn acreage in a watershed);

  5. have an economic value in dollar terms (e.g. the services provided by water-purifying wetlands, the revenue generated by eco-tourism);

  7. get the public involved in indicator measurements and observations (e.g. monthly survey of the presence of cyanobacteria along the shores, quantifying and collecting litter in certain areas);

  9. ensure that all Quebecers (and not just those currently involved) appreciate the value of the St. Lawrence and have a desire to preserve it.