Duckweed: What is it? When you type in “duckweed”, or Lemnaceae, if you choose to use the scientific name, on your computer, you see countless entries on how to get rid of duckweed from your pond, how much duckweed can be a nuisance when it gets stuck in your fish filter, etc. However, this is a plant that can be underestimated. I chose to work with duckweed in my project because of the countless ways it can help the environment.
This cheap aquarium plant can be bought at your local pet store, and is a source of food for not only animals, like fish and common livestock, but to us human beings as well.The main reason, however, why I chose working with this plant is because of how it can filter water, by breaking it down to biomass (the leaves and roots of duckweed), and treated water. Duckweed is a simple, aquatic plant that consists of two-to-three small thalloids, or plate- like leaflets that floats on or just under the surface of the water, which may or may not have simple rootlets. As I have mentioned, the scientific name for duckweed is Lemnaceae. Lemnaceae is from the order Alismatales, and the family Araceae.
The largest thalloids can get up to ? f an inch, while the smallest ones can get less than 2 millimeters long. The type of duckweed I used for my experiment, the “Wolffia Brasiliensis” has small, teardrop shaped thalloids. Reproduction for duckweed is not a problem. As investigated by Landolt and Kandeler in their book “The Family of Lemnaceae - A Monographic Study,” “a thumb-sized planting can cover 1.
2 acres in 55 days if undisturbed”. University of Toronto professor R. L. Jefferies conducted an experiment in 1991concerning the population growth, coming up with similar results. Duckweed reproduces asexually, by repeatedly cloning itself.
On each plant, there are fronds, which gradually grow new buds in its meristematic zone as it matures. The meristematic zone, which is located near the center of each frond, is a site within the plant where an organized structure of dividing cells is located. As each new frond matures, it starts the formation of new fronds. Each daughter frond begins as a bud in the meristematic zone along the central part of its mother.
It then emerges from the pouch on the side of the mother where it was initiated. Each new frond is connected to its mother frond by a strip of tissue called a stipule, or stipe.The stipule lengthens as the frond matures. When the daughter frond reaches full maturity, the stipe breaks off to release a new cluster. By that time, in rapidly growing duckweed, the newly released frond will have already opened new daughter fronds. The basic concept of a duckweed wastewater treatment system is to farm local duckweed on the wastewater that needs to be treated.
The plants grow rapidly, and acts as a nutrient sink, absorbing calcium, magnesium, nitrogen, chloride, sodium, potassium, and phosphorous from the water.The mat of duckweed filters and purifies the wastewater; however it does not seem to affect strong chemicals and heavy metals. Duckweed functions as a bioremediator by filtering contaminants such as bacteria, nitrogen, phosphates, and other nutrients from natural bodies of water. In my experiment, I studied the differences between purified and filtered goldfish water and the control water.
The type of duckweed I used was the “Wolffia Brasiliensis”, which is the one of the smallest species of Lemnaceae. The Effect of Duckweed on Natural Pollutants: Part II- The ExperimentTo conduct the experiment, I started out with two portions of the duckweed “Wolffia Brasiliensis”, two plastic containers (5 ? inches by 10 ? inches), and ten goldfish. In each container, I put five fish. In one container, I put a portion of “Wolffia Brasilensis” in, as well as the fish flakes for food. In the control container, I put only the fish flakes. I planned to not change the water for a week to see the maximum discrepancy between the two containers.
I took observations each day to keep up with the experiment.Within three days, four fish had already died. Only one fish was from the duckweed ontainer, and the other three were from the control container. After another three days, three fish had died, with two from the control, wiping all the population there out, and the remaining three goldfish were from the container with duckweed. When the goldfish died, they were floating on the top of the water, and their stomachs had a shiny, iridescent sheen. The bodies were deflated, and the stomachs had a cut through them.
When observed, I saw that the water with the duckweed was considerably clearer, as well as less of the solid, stringy white material that was the fish feces.The water lacking the “Wolffia Brasilensis” had cloudier, foggier water, and an increased number of the fish feces. However, when I tested the acidity of both waters using pH paper, both containers had a normal pH of ~7. However, when further compared to drinkable water, and further filtered, the waters in both containers were still not fit for drinking.
There was still a substantial number of solid wastes, and when studied under a focused and zoomed in view, there is still evidence of bacteria, and when I observed a sample under a microscope, I could still see proof of the microbes in the water.The Effect of Duckweed on Natural Pollution: Part III- Conclusions The potential of duckweed is very high; as supported by the evidence of my experiment, Lemnaceae does make a difference in the water quality. Duckweeds have received research attention because of their great potential to remove mineral contaminants from wastewaters deriving from sewage works, and polluted water. Duckweed is one of the fastest reproducing plants in the world, and therefore can cover a large area of land in a matter of days.In the future, it is entirely possible that duckweed can replace an expensive filter and/or purifier. As proved by my investigation, it removes a number of bacteria and minerals that can pollute the water.
Not only can duckweed be used for water filtration, it can be used as food for aquatic animals, and when dried, for livestock. Duckweed is also used in the dishes of many countries in Southeast Asia, because of its high source of protein. So who knows, maybe duckweed could be known as “Renaissance Plant”.
