Gatineau Park is beautiful–that is actually a pitiful understatement–but it is much more than that. It is fascinating. The same goes for my favorite lake in the park.
There are more than 50 lakes in Gatineau Park, including Lac Pink, (or Lake Pink as it is more prosaically called in English),which is my favorite. It is one of only 58 known meromictic lakes in North America. A meromictic lake is a lake where the upper and lower layers of the water in it never mix. That seemed very strange to me. Normally a lake’s waters mix all the time especially during spring and autumn when the water density and air temperature distribute nutrients and oxygen throughout the lake, more or less evenly.
The water of Lac Pink doesn’t mix like most lakes because it has a relatively small surface surrounded by steep cliffs that protect it from the wind which would otherwise mix the waters. As a result there is no oxygen in the deepest 7 metres of the lake. The deepest part of the lake has not has not been in contact with the air since the last Ice Age 10,000 years ago. That amazed me.
The lake is beautiful but it is not pink. It is named after the Pink family which were the first non-indigenous owners of it. The lake is actually green, not pink. The reason it is green, a gorgeous green in fact, is because of the presence of microscopic algae. The beautiful green colour is actually a bad sign. The green algae gradually takes over the oxygen in the lake suffocating the life in it. This is a natural process called “eutrophication” which ordinarily takes thousands of years.
However eutrophication can be affected by human activities. For example, Lake Winnipeg is suffering from it because of runoff from agricultural lands, sewage deposit by the City of Winnipeg as well as other municipalities into the Red River, and other causes.
Because Lac Pink is so popular (I am not the only one who loves is), people have sped up the natural process of eutrophication. At one time eutrophication was happening so fast it was estimated it would be complete within decades rather than a thousand years. As a result the lake has been rehabilitated. Humans caused the problem and now have come to the rescue of the lake. We can be a force for good or ill. The choice is ours. Conservation efforts have included building platforms and a trail to limit damage by erosion. Volunteers have also helped to plant 10,000 small trees.
Since there is no oxygen at the bottom of Lac Pink there is really only one organism that is able to live there without oxygen. This is a a prehistoric anaerobic organism. It is a pink photosynthetic bacterium, which uses sulphur instead of oxygen to transform sunlight into energy. Imagine that. It transforms light into energy even though it does not photosynthesize. This lake is endlessly fascinating.
Higher up in the lake resides the three-spined stickleback fish, a saltwater fish left behind from the Champlain Sea, which used to cover the region. This little saltwater fish adapted to the lake’s gradual desalination and today lives in the lake’s fresh water.
The Champlain Sea was a temporary inlet of the Atlantic Ocean that was created by retreating glaciers just after the last Ice Age. The Champlain Sea once included much of the land that is now part of Quebec and Ontario and even parts of New York and Vermont. The huge continental ice sheet that covered much of North America during the last Ice Age was so heavy that it depressed much of the rock beneath it. When the Ice Age ended the St. Lawrence and Ottawa River valleys were so low that they were actually below sea levels. These areas flooded with sea water when those massive continental ice sheets from around the world melted and raised sea levels substantially, once those ice sheets no longer dammed the oceans back.
Then the land gradually rose as the Ice sheets were removed. This is called isostatic rebound and is still happening to this day all over Canada, including for example, Lake of the Woods where we have a cottage. The Champlain Sea lasted for about 3,000 years from 13,000 to 10,000 years ago. As a result the sea coast gradually retreated to its current location. Of course, since the process of isostatic rebound is not yet complete, those coastlines will continue to change. This process will now also be affected by rising sea levels due to climate change. This area, as so many others around the world, will be in for interesting times, not all of which will be benign.
The remaining glaciers fed the Champlain Sea making it more brackish than typical sea water. It has been estimated that the Champlain Sea was as much as 150 metres (490 ft.) higher than the level of the St. Lawrence and Ottawa River valleys today. Scientists are so smart to figure all of this out.
There is much evidence of this former sea including the clay plain deposited along the Ottawa and St. Lawrence Rivers that have resulted in such interesting forest types that I travelled through on this trip as well as large wetlands that are home to amazing vegetation, including my favorite, orchids. Other evidence of the sea includes whale fossils and marine shells that have been found near Ottawa and Montreal. There are also fossils of other oceanic fish such as capelin.
This entire notion of an ocean in this area is astonishing. About 11,000 years ago when the land was so low after the Ice sheets were gone from southern Canada, the Atlantic Ocean rushed into the St Lawrence River Valley filling even the area of current Ottawa with ocean water. In other words, a mere 11,000 years ago there would have been bowhead whales and seals swimming above where we were standing today. I am always amazed that much of Manitoba at one time was the bottom of an ocean, but that was 450 million years ago! Comparatively, 11,000 years ago is just a blink of an eye ago.
Nature constantly astounds! Gatineau Park is an example of that.