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Musings about the environment and all it touches, from education to city planning

Tale of a Wetland at KDocs

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Last Friday KDocs screened the movie Metamorphosis: Tale of a Wetland, directed by Bryan Maltais, as part of the conference on wetlands conservation organized by the Burns Bog Conservation Society.  They invited me to be a speaker and participate in a panel.  Here is what I said (sorta – I tend to ad-lib a bit).

 

 

 

We don’t like wetlands, it seems. We talk about muck and ooze. We get mired.  We get swamped.  We get bogged down.  We have inflicted a lot of damage on them.  We have drained them out. We have filled them up.  We have dumped garbage over them; the largest garbage dump in the world, Fresh Kills in New York, is an artificial mountain built over a swamp.  Even here, our own Vancouver Landfill has covered up a big chunk of Burns Bog.

And we seem to fear them.  Swamps are alien. They are the out-there, the chthonian, the other.  Maybe the can be admired in their own right, as a home for weird and amazing creatures.  But they are not a place where people feel home.

Or are they?  I want to make a case that wetlands are useful to us.  They can provide us with resources, including shelter; purify our water; prevent floods; fight climate change.

Indeed, there is a paradox.   Alien as wetlands may be, we have been seeking them throughout history.  Many of our great cities are built on swamps: Paris, Shanghai, London, Mexico City, Venice, Berlin, or Chicago, for instance.  Why?

Take Chicago.  The name is thought to refer to a type of wild garlic that grows in wet environments.  First nations found the location convenient for harvesting and trading, and settlers followed.  Wetlands are very productive environments, actually; think of rice and cranberries.  Wild rice, as the name implies, can be harvested sustainably from natural wetlands.  In Europe, 20,000 tonnes of reeds are harvested annually from the Danube delta – to make thatch roofs.  Here in the Lower Mainland, first nations used to harvest wapato, an aquatic tuber (also called swamp potato). 

Wetlands, in fact, provide optimum conditions for plant growth: sunshine, and of course water. Provided that fertilizing elements are present, the productivity of a wetland is higher than that of a rainforest.  This is also true of the animal resources, fish and waterfowl in particular.  These disappear when wetlands are drained.  To take one example from European history: we often learn about the heroic efforts of land reclamation of the marshlands in northern Europe along the North Sea and the Baltic Sea.  The diking and draining of the English fens, of the extensive wetlands in Brandenburg and Pomerania, to say nothing of the Netherlands, are well known and presented as the linear march of progress.  But there has always local inhabitants who saw it differently.  As late as the mid eighteenth century, Frederick the Great, king of Prussia, had to send in his army to protect the newly reclaimed lands.  The marsh dwellers who had been destroying dikes as fast as they had been built were eventually subdued and pacified with a promise of 20 hectares of farm land, but (in the words of historian David Blackbourn), “many found it difficult to trade the fish hook for the land plough.”

If wetlands provide us with food, they can also be a source of water – clean water.  Marshes have a filtering effect that has been amply demonstrated in thousands of wetlands, both natural and constructed.  I’ll just use one example – a giant one.  The Great Black Swamp was a wetland at western end of lake Erie, half of the size of the Lower Mainland.  Dan Egan writes “It was lake Erie’s kidney, a grand filtering system that turned muddy rainwater flushing off the land into crystalline flows by the time they reached the lake.  And it was replaced by a drainage organ that does quite the opposite.”  The Maumee river that drains the former swamp is now highly polluted with phosphorus, which feed blooms of blue-green algae on Lake Erie.  The 2014 bloom of a particular algae, microcystis, made the waters of west Lake Erie so toxic that the drinking water supply of the city of Toledo had to be shut off, depriving nearly half a million people of drinking and washing water for three days.

One key benefit of wetlands is flood reduction.  Again, I’ll give you one example.  In August 2011 Tropical Storm Irene battered Vermont.  Otter Creek flooded the town of Rutland, destroying homes, roads, bridges.  But the town of Middlebury, downriver, was spared.  That was because the Otter Creek Swamp Complex, located between Rutland and Middlebury, stored the floodwaters and gradually released them.  Many cities are finding that protecting wetlands is more effective, and cheaper, than building flood control infrastructure. One study valued the ecosystem service of flood prevention at $33,000 per hectare, annually.

Finally, wetlands store carbon.  Coastal eelgrass marshes are so important in this respect that the phenomenon has been given a name: blue carbon.  Blue carbon, that is, the removal of excess carbon from the atmosphere, is a key component of climate change.  Salt marshes and estuaries capture about five hundred million tonnes of carbon every year; this so-called blue carbon is enough to offset half of all the emissions from cars, trucks, ships and planes worldwide.

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Written by enviropaul

October 15, 2018 at 6:28 pm

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