Many people reading the post title will think: What the heck is a Daphnia? A Daphnia is a tiny zooplankton - the little organisms in lakes and oceans eaten by fishes - with an average length of 1/3 mm and is a species very common in fresh water bodies. All the images in the post are taken with a microscope from one of our samples collected in Vobster Quay in mid-May and the first one precisely shows a (dead) Daphnia. Since our microscope does not have a place to insert a specific microscope camera, I used the microscope adapter Snapzooms which is cheaper and very simple to use and smartphones offer nowadays as much resolution as microscope cameras.
The Daphnia is often called water flea because of its saltatory movement when it swims or escapes from predators. Watch the first minutes of this video, they are very impressive. If you want you can also buy them on EBay :). Its shape, like a transparent balloon, is a very characteristic anatomical features as well as its tail and antennas - that kind of arms near the head. The other two images below show a Copepod and a small Cladocera - the Suborder the Daphnia belongs to.
And this is the result of the count of our sample obtained collecting the zooplankton from the surface down to 25m in Vobster Quay in the Eastern part of the lake :
The lake is mainly populated by Daphnia - relatively larger than the same organisms in the Western part - followed by Copepods. Some copepods were very tiny because in the immature life stage. So exactly what I was looking for, a stratified lake with a lots of Daphnia inside!