Paleolimnology is a scientific subdisciplinne closely related to limnology and paleoecology. Limnology is the study of any inland
water body including rivers, lakes, even ground waters, fresh or salt. Paleoecology is the study of past climate conditions in an
area using a number of techniques including chemical analysis and the study of diatom species and populations in lake sediments.
studies are concerned with reconstructing the paleoenvironments of inland waters and especially changes associated with such events
as climate change and human impacts. Depending on the study and the methods used, the time scale for climate reconstructions
can vary from thousands to millions of years or can be applied to changes which have occurred in the recent past from less than 10
to 150 years.
In late summer 2014, Professor Jesse Vermaire, Assistant Professor of Environmental Science at Carleton University
(Ottawa), recovered a sediment core for study from White Lake. He was assisted by Conrad Gregoire and Janet Taylor of the White
Lake Preservation Project. The core sample was taken midway between the eastern tip of Hardwood Island and the western tip of McLaughlin's
Island. The core represented approximately 150 years of sedimentation at that location. This project was a student project undertaken
by Kathryn Sweet under the supervision of Prof. Vermaire.
Collecting the sediment core, dividing the core into 1 cm subsamples and recording vital data
Prof. Vermaire has provided
us with a summary conclusion of the work done thus far:
"The main conclusion of the work to date is that there is evidence for some
recent increases in erosion and nutrient enrichment in roughly the last 5cm of the sediment core. The erosion is shown by the decline
in organic content near the top of the core which suggests increase input of inorganic material to the lake, presumably as a result
of land clearing and greater erosion. The nutrient enrichment is indicated by the increase in the relative abundance of the diatom
species Fragilaria pinnata and the decline in the chrysophyte to diatom ratio. Fragilaria pinnata are in some respect the “weeds”
of the diatom world and can grow well under low light and higher nutrient conditions. Chrysophytes are another kind of algae that
thrive in lower nutrient conditions and therefore a decline in the chrysophyte to diatom ratio suggest nutrient enrichment. Overall,
there is evidence of some recent nutrient enrichment."
The author of the report, Katherine Sweet, states in the abstract of her
“White Lake is a large, shallow lake with unique characteristics and a sensitive ecosystem. A shift encountered in the chrysophyte
to diatom ratio and an increase in Fragilaria pinnata within the last five centimetres of the core sample is indicative of recent
water quality changes within the lake. The variation in species abundance and loss of biodiversity encountered in the sediment sample
over time is likely due to increasing anthropogenic nutrient additions to the system. These impacts are visible in the diatom-inferred
decline of water quality revealed in this study.”
Fragilaria pinnata (left) and Chrysophyte (right) diatoms