The Bras d’Or Lake Biosphere; a primer

By Dr. Annamarie Hatcher, Board of Directors

The Bras d’Or Lake Biosphere is so much more than local people designating their place as special. We are an international showcase for ‘how to do it right’ designated by UNESCO’s Man and the Biosphere Program (MAB). MAB is an Intergovernmental Program that aims to establish a scientific basis for the improvement of relationships between people and their environments.  In our Biosphere Reserve we see solutions which balance the conservation of the natural environment with its sustainable use.  So, the demise of Cape Breton’s coal and steel industries has put us in a good position to develop a model of sustainability and community-based economic development in the naturally beautiful Bras d’Or environment. 

So, what is unique about this environment that we want to take care of? The natural beauty is obvious whenever we drive along the shore of the estuary. The Bras d‘Or Lake and watershed covers over 3,500 km² of forest and watery ecosystems in the centre of Cape Breton Island.  The Lake is not really a lake or an inland sea. It is actually an estuary where fresh and salt waters mix. The estuary occupies 31% of the Biosphere  and the rest is watershed.  There is over 1,000 km of coastline with plenty of fine beaches for swimming and sheltered coves to moor a boat. The animals that call the estuary home are descendants of ancestors from times past when the sea levels and water temperatures were different. Up until about 5,000 to 6,000 years ago, the Bras d’Or Lakes were tiny fresh water lakes or ponds connected to the Atlantic Ocean by long river systems. As sea level rose with the retreat of the glaciers it reached the level of a bedrock ridge in the Great Bras d’Or channel and salt water started to flood into the lowlands of the Bras d’Or Lake as we know it today.      5,000 to 6,000 years ago                                    present day – Photos courtesy of Dr. John Shaw 

Over long periods of time, the sea level has risen and fallen and the surrounding ocean has been warmer and then colder than it is today. Because of the many protected pockets of water both deep and shallow, the present day Bras d’Or Lake still provides a home for unique species that arrived from the arctic and other species from the sub-tropics during those earlier times. Some tiny shrimp-like animals and segmented worms abundant in the deep, cold waters of the Bras d’Or Lake are not found anywhere else outside of the high arctic. The oyster, a flatfish species and many other species of segmented worms which shelter in the warm, shallow waters of the Bras d’Or Lake are not common elsewhere north of Virginia!  A single body of water providing a habitat for arctic as well as sub-tropical species of many types makes the Bras d’Or Lake truly unique. Over 30^o of latitude are represented over distances of less than 10 km!