Q1-2017 Update #1

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How Friends of the Muskoka Watershed hopes to solve Muskoka's calcium decline problem which is negatively impacting our forests and lakes.

Every living plant and animal needs Calcium (Ca). Ca forms about 4% of our body weight not counting the water. Mammals, including you and me, use 99% of the Ca in our bones and teeth, while molluscs and Crustacea use theirs for their shells, crusty carapaces, or scales. All animals also need Ca for our nerves and muscles to work. We'd simply be dead without it, and with too little Ca we suffer from osteoporosis. Plants need Ca too. Tree canopies for example are 1/3 to 1% Ca by weight. Calcium holds plant cells together, and without enough Ca, plant growth is distorted in a kind of "plant osteoporosis". But there's a problem. Ca levels have been falling in forests and lakes in Muskoka for the last several decades, and levels have now fallen to the point where damage is obvious. This is a kind of "ecological osteoporosis" at the scale not of individual plants and animals but of entire watersheds. Here we explain: the scope and severity of the problem; its cause; what it might mean for all of us in Muskoka; and what Friends of the Muskoka Watershed is doing about it.


The Scope and Severity of Ecological Osteoporosis:

Lakes provide the clearest evidence of declining Ca levels at a large scale. The Canadian Wildlife Service (CWS) sampled 195 Muskoka lakes by helicopter during the 1980s, and less than 10% of the lakes had Ca levels in the "red", i.e. below 1.5 mg/L, a level at which damage to lake life occurs. By the early 2000s, when they repeated the survey, half of the lakes had less than 1.5 mg/L, an enormous increase in the lakes at risk. On the right you'll see how many more of the lakes are "in the red" in the right-most column. While these lakes were sampled only once in each survey, more intensive work conducted at the Dorset Environmental Science Centre and several Ontario universities confirm the trend. Calcium levels have fallen in the vast majority of lakes, to levels where it is now a widespread and serious problem in Muskoka, but what caused it?



The Cause:

Lakes get their Ca mainly from the soils in their watersheds, so declining lakewater calcium is linked to a shrinking pool of mobile calcium in catchment soils. Ca is added to soils from above, in atmospheric dust and precipitation, and from below, in the weathering of parent materials. It is removed from the soil by acid rain which leaches soil Ca, and repeated cycles of forest logging and re-growth. The role of acid rain is complicated and varies from place to place. Where soil Ca pools are large and readily replenished, for example in thick soils overlying limestone-rich bedrock, acid rain will increase soil leaching and lake water calcium concentrations without lowering soil Ca pools. However, in Muskoka, where watersheds have thin soils overlying weathering-resistant, Ca-poor bedrock, soil Ca pools have been majorly depleted, necessarily lowering Ca in downstream waters. Reduced acidic deposition will eventually help, but in the near term, it worsens the trend as any residual soil Ca is leached at a slower rate. It is likely that Ca levels in many Muskoka lakes in the northeast part of the watershed have already fallen below pre-acid rain levels. They are likely now at levels beyond the evolutionary experience of lake biota, and these biota are suffering in consequence.


What It Means For Us:

The damage caused by ecological osteoporosis is now widespread and all around us. In the forests, Ca decline is slowing the growth, seed production and seedling regeneration of sugar maples, with implications for current or future forestry, autumn splendour, tourism, and maple syrup production. In lakes, crayfish, with their high Ca demands are in major decline across the watershed, and even more Ca-rich species including molluscs can't be far behind. They are as yet unstudied. And there has been a major offshore change in our lakes — jellification. There is now a bead of jelly in every litre of Muskoka lake water. Each jelly bead (see a handful of them on the right) is the "home" of a planktonic animal called Holopedium, that does not calcify its carapace. As lake water Ca levels have fallen, the jelly-clad Holopedium is outcompeting the native Ca-rich species called Daphnia. With losses of several species of Ca-rich animal plankton the risk of algal blooms in our lakes has increased.


What FMW is Doing About the Problem

The solution to this problem of "ecological osteoporosis" requires ongoing national and international efforts to combat acid rain, but relying on acid rain control alone may not be enough, and it may take a very long time, perhaps centuries to work. Fortunately, FMW believes that active local engagement can help solve this problem. We must become "gardeners of the forest", returning the calcium to forest soils that acid rain and logging have removed. FMW has just received an Ontario Trillium Foundation Seed Grant to help solve this problem using Ontario's first residential wood ash recycling program designed to return the minerals from wood, including Ca, to the forest where it originated. In doing so we will turn a waste product into a useful forest fertilizer. We call this program HATSEO, for "Hauling Ash to Solve Ecological Osteoporosis".

The overall objectives of the program are:

  1. to explore, create, test and refine an optimal way to collect and store wood ash from seasonal and permanent residents and commercial or industrial sources in Muskoka, and to distribute the ash to the parts of the watershed most in need of calcium, and
  2. to conduct the research needed to quantify the chemistry and solubility of residential wood ash, and its potential toxicity in order to address the regulatory requirements that would need to be satisfied to implement a regional-scale, wood ash recycling program.

Do you have ash from your wood stove, fireplace or home boiler? Are you willing to have it used to help solve this widespread calcium decline program in Muskoka, while building a community-based, wood ash recycling program? If so, please contact Dr. Shakira Azan at FMW – – who will be running the program. That's her on the right, and FWM needs your ash!

You can also fill in our on-line survey.


Friends of the Muskoka Watershed
PO Box 416, Bracebridge, ON P1L 1T7