Declining calcium levels in Ontario lakes is a growing concern.
Under natural conditions (i.e., without human influence), calcium levels in soils are governed by inputs from mineral weathering of rocks and atmospheric deposition of calcium-rich dust, and losses through uptake by growing forests, and leaching to lakes and rivers.
The two main human causes of calcium decline in soils, and thus in lakes, are acidic deposition (“acid rain”) and forest harvesting. (source : Dorset Environmental Science Centre / Dr. Norman Yan)
Falling calcium levels mean a zooplankton called Daphnia (water fleas) cannot get the nutrients they need to survive and reproduce, and are consequently consuming less food and becoming more susceptible to predators, leaving more algae for other organisms to feed on. ( source: University of Cambridge)
This leaves Holopedium, a small, jelly covered organism to take advantage of the extra plankton to feed on. The excess quantities of Holopedium are multiplying so greatly, that they are clogging up water pipes, and disrupting the natural order of the food chain.
What can be done?
- Support the government’s efforts to reduce SO2 and NOx emissions to reduce acid deposition rates
- Work with the Ministry of Natural Resources and Stewardship Councils to consider soil nutrients, especially calcium status, when they set logging quotas.
- Join Ontario’s Lake Partner Program to help to gather more monitoring data for Ontario’s lakes. You can visit www.ontario.ca/lakepartner for more information.
(source : Dorset Environmental Science Centre / Dr. Norman Yan)
See the Resources section for further studies and information.