Plants and other green stuff in the pond sample

In order for my pond sample to be healthy I included some green stuff to provide oxygen. I had no idea what they were at the time but they were green so I figured, like vegetables on my plate, they are good to include.

Lemna minor (Lesser Duckweed)

The floating tiny Lilly pad looking plants are Duckweeds from the Lemnaceae family. They float on the surface of the water with a single root hanging down.

When I collected the water from Altona Marsh, my jar and hand was covered with them. I have seen them so thick on some ponds that you cannot see the water below. In situations like that they shut out the light and the plants below die along with the herbivorous insects that feed on them. Yet, they can also be a good tool for filtering and cleaning water. From what I read there is still a lot of research going to find ways to use them to clean up the environment.

I think what I have in my sample is Lemna minor (Lesser Duckweed). The common name Duckweed comes from observing ducks feeding on these tiny plants. They are high in protein, more than soybeans and are eaten by people in some cultures. Since they stick so well to my fingers I imagine that they stick well to ducks feet and are thus transported from pond to pond.

Another plant I think I have identified in the water is a Liverwort called Riccia fluitans. They grow just below the surface as you can see here. The branched thallus is darker green and thicker than the duckweed. They will also grow on damp soil and in that case, according to Ann Morgan (Field Book of Ponds and Steams), they can be reddish or purplish. Her book was written in 1930 so I wouldn’t swear by it but you can bet that the next time I go to Altona Marsh I will be looking.

Riccia fluitans

A third plant I have in the jar, I believe is a green alga species in the genus Chara called Chara vulgaris. What I’m talking about is the plant that has a defined stem and a whorl of leaf like structures along the stem as pictured below.

Chara vulgaris

There are lots of algae in the jar as well. The long stringy algae might be Zygnema species.

Zygnema species

Desmids are green algae cells that are often found in bogs similar to Altona Marsh where I found these. This crescent-shaped one is a Closterium.

Closterium

Below are some other shapes of algae that I found. Even though I don’t know what they are now I find them totally fascinating to look and loads of fun to find.

You can see some Diatoms in the photo above as well as algae.

Damselfly nymph in winter

At the end of October I took a walk to Altona Marsh and collected some of the water along the track.

I just filled up two plastic peanut butter jars and made sure I had some duckweed, algae, sediment from the bottom and bits of other stuff. I didn’t really look to see what I had. With two jars I was sure to get something interesting.

Sure enough, after the water settled for a few hours I was able to see an Odonata nymph. The three leaf-shaped gills extending from the hind end of the body indicates that it is a damselfly. I haven’t a clue what species this is. They overwinter as nymphs and emerge in late spring. They are very predacious and eat every kind of aquatic insect, small crustaceans and snails so I think there will be plenty of food in this one jar for a while. I have actually seen a few things disappear since March and I suspect this is the culprit. Most of the time it just sits and waits for a victim to come by.

I soon realized that I was going to get distorted photos from the jar so I bought a small rectangular plastic tank which made it easier to get close up with my camera. Just recently I took the photo below. I think it must have molted because it is so clear and you can see the insides. Earlier it was emerald green. They molt between 6-15 times. With each instar the nymph get darker in color. Now you can clearly see the tracheal gills and tracheae and lines with the consequent flowing of the blood throughout. I think the darker part in the middle is its heart.

You might be able to make out the labium that looks like its chin. When it is ready to catch something the labium flies out with the swiftness of a frogs tongue and grabs it’s pray and snaps it back into its mouth. I watched it stick part of it out and place its front legs up as though it were cleaning the tip. I wasn't quick enought to get a photo but here is another view.

When I turned the container around it would bend its body to move the tail in my direction. I wonder if that was some sort of defense action. It did it several times.

They move about slowly by crawling or swaying like a fish by sweeping their tail from side to side. It has been really fun to watch especially as the snow falls.

Check out other blogs about water at Watery Wednesday.