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Celebrating RBG’s Wetlands

February 2, 2021

By Barb McKean, Head of Education, Royal Botanical Gardens.

What’s so special about wetlands?

While the department at RBG that cares for and manages our non-garden properties is called Natural Lands, it’s a bit of a misnomer as they are also responsible for a lot of water – almost 1/3 of the area we own is wetland habitat. To recognize World Wetlands Day today, let’s take a walk on the wet side at Royal Botanical Gardens and find out a bit more about our spectacular wetlands.

What is a wetland?

Simply put, it’s just a part of the landscape that is, well, wet…. for at least a good part of each year. In wetland habitat, water influences all natural processes, be they biological, physical or chemical.

What kind of wetlands are found at RBG?

While some of our woodlands feature vernal pools (small woodland depressions that hold snow meltwater and other precipitation) our wetlands are mostly rivermouth marshes, with some inset swampy areas. These are defined by water levels that fluctuate over the year, and emergent vegetation like cattails, rushes, sedges and reeds. Deeper water features floating-leaved plants like waterlilies.

Technically, our marshes are extra special as they are Great Lakes Coastal Marshes – areas dominated by emergent vegetation that are subject to the rise and fall of these huge bodies of freshwater.

What’s so special about Cootes Paradise Marsh?

This area is a Provincially Significant Class 1 Wetland. Top notch. Numero uno. In wetland terms, that is. Separating wetland habitat into classes is a planning mechanism carried out in Ontario that evaluates wetlands based on a set of criteria and ranks them against each other. Wetlands are assessed by looking at their ecosystem values (including for habitat, biodiversity, fish spawning and groundwater storage), and their social values (the benefits they offer to people, like filtering water, storing carbon, preventing flooding, their Indigenous values, and use for education, research, harvesting activities, and recreation).

Besides a Class 1 Wetland, what other special designations does Cootes Paradise Marsh have?

Plenty! Cootes Paradise became a fish sanctuary in 1874, and was included in one of Ontario’s first Crown Game Preserves, becoming protected in 1927. It is recognized as an Important Amphibian and Reptile Area (IMPARA) and part of a National Important Bird Area (IBA). It is also part of a National Historic Site of Canada, and the Niagara Escarpment UNESCO World Biosphere Reserve. It is also a provincial Area of Natural and Scientific Interest, and an Environmentally Sensitive Area.

How much can the depth of RBG’s wetlands fluctuate?

Lake Ontario’s water levels are managed by dams at the east end of the lake, but even without management, the Great Lakes’ water levels can trend higher or lower over several years due to precipitation changes across their watersheds, and in recent years we’ve seen fluctuations of 1.25 metres over a few months. Things can change more rapidly during heavy windstorms as the result of a natural phenomenon called a seiche. This occurs when prolonged strong winds push water to one end of the lake. When the wind roars from the east for a few hours, water piles up at our end of the lake, squeezes through the Burlington Ship Canal and the Desjardins Canal and can raise the water level of Cootes by 40cm or more over a couple of hours.

Cootes Paradise Marsh? Dundas Marsh? Which is which?

They are one and the same. The oldest name recognizes Thomas Coote, a British Army lieutenant stationed at Fort Niagara from 1778-82. This area was apparently his hunting paradise when on leave, and his name stuck, enough to be officially recorded when John Graves Simcoe and his wife visited and dined on turtle and salmon taken from the marsh in 1794. Located at the west end of the marsh, the Town of Dundas was originally known as the Village of Cootes Paradise. Dundas Marsh doesn’t appear as a name until well after 1814 when the village was renamed for Henry Dundas, the former British Secretary of State.