Debra Anthony recently sent out a link to the Muskoka link report card: It is only a summary report, the in-depth data is to come later. However it is very interesting in its own right and I would just like to make some comments vis a vis Chandos.
(Previous Muskoka Report Cards can be found here.)
Firstly, lake Muskoka is a huge lake. In terms of water volume, it is a good 8-10 times larger than Chandos, and on average is about 5 metres deeper.
Days of Ice Cover
The depth and the amount of water in Lake Muskoka mean that it will take longer to freeze and longer to thaw. They note that since 1975 the ice cover duration has decreased by about 20 days, (slope of approx 4 days per decade.)
Below is the Chandos Ice Cover data going back to 1986. Our ice cover loss on a straight line basis is about 3 days per decade.
In comparing the shape of the two graphs, they seem to be reasonably correlated, likely indicating that they are subject to near similar weather regimes.
What has been happening on some other lakes as a result of climate warming is that they are now experiencing multiple freeze/thaw cycles in a single winter. This is something we definitely hope not to see here, but it may be in our future.
Reduced Calcium Concentrations
Calcium levels in Ontario Lakes have been in decline for awhile. In the Muskokas there are low levels of Calcium in the water, and this is a cause for alarm as different organisms need calcium for bones, shells, etc. In Chandos, however, we have loads of Calcium, with concentrations probably 5 times that of the Muskokas, so we do not have a similar calcium problem. My own suspicion is that the calcium levels in the lakes have declined since we cleaned up the acid rain problem, as the acid would attack the rocks and limestone increasing the calcium in the runoff. There is complex chemistry in the calcium cycle and changes in pH and carbon dioxide levels both affect the cycle. Please note, however, I have not researched this in any depth and am not a chemist.
To read more, see the section at Chandossier.com under the Geology tab.
Saltier Waters, (Chlorides)
Muskoka is noticing an increase in chlorides in the lakes. Most likely this is due to road salt and runoff. At Chandos, we have a significantly smaller watershed, with, I suspect, fewer roads requiring salt. The 2014 Paleo study at Chandos did report increased Sodium Chloride in Gilmour Bay. This may be due to extra road salt being applied on the hills that run quite close to the Bay in a few spots.
The following is a quote from the Hollingsworth 2014 paleo report:
Modern limnology revealed that the hypolimnion of Gilmour Bay is more anoxic than South Bay and as a result had elevated levels of nutrients (N and P). Although the late summer anoxia may be a chronic condition, it is likely acerbated by the recently elevated levels of ions related to road salt use (NaCl; a deicing agent on Canadian highways). This anthropogenic salt addition would increase the density of bottom waters and increase stratification, thereby reducing mixing and oxygen in the deep waters. This results in an increase in nutrient concentration in the hypolimnion, leading to a greater pulse of nutrients released from the hypolimnion to the epilimnion during fall overturn. This can lead to greater algal production at overturn.
Increase in Algal Blooms
Harmful agal blooms are on the increase and scientists don’t know why.
To learn more, look at this recent paper on the subject:
Cyanobacterial blooms in Ontario, Canada: continued increase in reports through the 21st century
Chandos Lake Science 2 