Limnological characteristics of 56 lakes in southern Quebec in relation to their trophic state
Recreational lakes in southern Quebec are under increasing anthropogenic pressure. As a consequence, an increasing state of eutrophication has been observed, associated with some negative side effects, such as loss of biodiversity and a rise in tolerant cyanobacteria. The first objective of our study was to document the relationships that exist between the geological setting and the limnological characteristics of the study lakes and the process of eutrophication. To this end, correlation, cluster and covariance analyses were conducted using a data set including 57 environmental variables. The correlation analysis usually showed a close link among the total phosphorus concentration, algal abundance and decreasing water transparency in all study lakes. In addition, an increase in primary biomass in eutrophic and hypertrophic lakes was correlated with increasing concentrations of dissolved aluminium. Our results also show that the geological composition of a lake’s watershed strongly controls its alkaline properties and, consequently, its level of primary production. Finally, our set of lakes represented a complete trophic gradient, with trophic conditions ranging from ultra-oligotrophic to hypertrophic. This data set provides a starting point for future studies into the relation between the trophic gradient and the structure of diatom communities in temperate lakes.