During high lake levels sand stored in dunes is eroded by waves. This sand reinforces the sand on the beach, but also forms sand bars (underwater dunes!) which act to ‘trip’ the waves and lessen the amount of wave energy reaching the beach. This is part of how dunes protect the coast from damaging wave energy. The other way is by providing a physical buffer or barrier between development and the beach. Erosion of the dune by waves is a natural process and part of dunes’ important function.

 

During low lake periods, beaches become wider and wind has more beach to blow across, picking up sand and carrying it back into the dunes. Dune building occurs during these low lake periods. These sand reserves will be necessary for the next high lake and storm events.

 

So, what makes them vulnerable?

 

Their vulnerability lies in how much people interfere with the natural processes and functions of the dune system. This interference can be as simple as damaging the anchoring dune vegetation, to extensive damage by vehicles or heavy equipment.

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The dunes, which are hills of sand, would blow away if it were not for the specially adapted vegetation that grows in this sand environment. Dune grasses like American Beachgrass, Great Lakes Wheatgrass or Long Leaved Reed Grass are just some of the species that grow on Lake Huron’s dunes, and are responsible for their creation. Without them, the sand would continue to blow inland, and those reserves of sand would not be present for future high levels and storms. The consequence would be landward migration of the shoreline, threatening buildings and resulting in the loss of the recreation potential of the beach.

 

In New Zealand, they stress the importance of the dunes by using the simple phrase “No vegetation, no dunes. No dunes, no beach.” It certainly captures the essence of how important our dunes are, not only to the environment, but to the economies of our lake communities.

 

Great Lakes dunes are among the most vulnerable ecosystems in Canada. They have undergone significant declines during the past century, largely as a result of shoreline development and recreational activities. Our diminishing dunes and their adjacent beaches are home to a number of rare species and plant communities. Conservation can ensure that our dunes are not lost due to complacency or neglect. Next time you’re at the beach, help protect our dunes:

 

• Use designated pathways across the dunes to get to the beach.
   

• Avoid trampling the dune vegetation. Without it, the dunes will be open to wind erosion.
   

• Educate others about the importance of dunes.

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Dune vegetation can be rare, even globally rare. Learn more about dunes and dune stewardship. The more you know, the more you’ll enjoy this natural ecosystem.

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