Wetlands are among the most productive ecosystems on our planet.
The richness of these transitional ecosystems relates mostly to the diversity of ecological niches created by the variability of seasonal and interannual cycles. Owing to the difficulty of distinguishing between natural and anthropogenic factors and, more importantly, the scope of the analysis that would be required, we were not able to develop a numerical index for the stress associated with the control of water levels on the St. Lawrence. The percentage of wetland losses resulting from anthropogenic disturbances can be assessed, however, by comparing the data on historical wetland losses and the data on remaining wetland habitat. These two datasets are available for roughly a kilometre-wide band on either side of the river. Although it appears unlikely that such losses could have exerted significant pressure on biodiversity on a regional scale, on a local scale, the available remaining habitat may have been reduced to the extent that a decline in biodiversity could be ascertained within the associated biological communities.