What is a constructed wetland filter?

Written by Bernie Kerkvliet 

What are they?
What do they do? 
Where do they come from?

Ecologically speaking, they are known as an Ecotone. An Ecotone is a transition between two diverse communities which contains organisms native to each overlapping community as well as organisms characteristic to the Ecotone itself.

In a wetland life is very dense and variable. Every ounce of water from this wetland environment contains millions of organisms that make up a highly diverse community.

The Plantonic community includes algae or phytoplankton, zooplankton and bacteria. Together, they are the plants, animals, and scavengers of this unique, aquatic ecosystem. The scavenger like plantonic bacteria along with fungi clean up the corpses, wastes, and organic debris present in the water. The algae transforms sunshine and inorganic nutrients present in the water, into food so it can grow and reproduce. In a nutshell, the bacteria, fungi, and phytoplankton all feed on impurities in the water and clean it as it flows thru the wetland. These are the base consumers of the ecosystem or the base of the food chain. The amazing thing is the phytoplankton and bacteria can produce another generation in a matter of hours to days.

Simply put, the phytoplankton represents the grass and herbaceous plants in a meadow. The zooplankton which are protozoans, rotifers and tiny crustaceans are the animals that feed on the plants in the meadow (Phytoplankton).

This basis for the food chain in turn provides food for insects, fish fry, larvae, etc. Aquatic plants also get their nutrients from the water and decomposing sediment in the wetland. The food chain continues to grow to include largerfish, frogs, reptiles and eventually includes mammals and birds.

Wetlands are also good for slowing the water down. In a constructed wetlands, we accomplish this by the size of pump supplying the wetland. Slowing the water down allows for sediment to settle out. In nature, after hundreds or thousands of years, sedimentation continues until a meadow is formed. The sedimentation process prevents soil from washing downstream. Since the water is almost stationary, it allows water to percolate down into the water table.

In a constructed wetland, the nutrient rich sediments are periodically pumped out on to the surrounding landscape.

The sedimentation process in both cases produces water clarity.

Wetlands, whether natural or man made are the most effective water purification systems on earth.

Wetlands can be created in many ways. They can be built by rivers in slow moving waters and delta’s that create wetlands. Lakes and landlocked basins can develop into wetlands also. 

Aquascape has developed a very effective arificial wetland system that is very effective. Whenever water filtration is required, I prefer to use a constructed wetland if possible.

One of the best ways nature has for building wetlands, man has destroyed in multiple ways. The best natural builder of wetlands is the beaver. All the industrious work the beaver has done in the northern hemisphere, man has slowly destroyed all in the name of two things, a hat and “progress “.  I hesitate to go to far into the history of the fur trade and beaver felt hats that became so popular in Europe, but that is what started it all. I’ll bring you a little more currant in North America.

The total land area in the contiguous United States is 2.96 million square miles. It is estimated that there were some 200 million beavers in the U. S. at the time white man came from Europe. It is also estimated that there were about 300,000 square miles of beaver ponds at that time. Can you imagine the benefits that brought to the land?  Better plant and animal biodiversity, slow moving water meant better water percolation and recharge in the water table, flood control, clear unpolluted water and those are just some of the macro benefits.

In the pursuit of fur, hats, farmland, industry, and “progress”, our land is not what it used to be.  That, my friends is why  the work we do is so important. Each pond, pondless, patio pond, fountainscape, stream and waterfall we build is like making another little island of biodiversity to continue on and helps sustain what we have. As my late friend Scott Hammond said, “We have gold to give”. Give it.

Stay thirsty my friends.