Daphnia!

Now that we have officially started our LIVE FOOD EXPERIMENTS, let’s take a closer look into the animal that makes it possible.

Daphnia are a small animal known as zooplankton. Their tiny size makes them a great snack for out trout, but also other creatures like macroinvertebrate larva. There are over 100 known species of daphnia! Trout in the classroom has used a few different kinds for our experiments over the years. These colonies can produce both sexually and asexually! Female daphnia can also release their eggs into the sediment where they sit dormant for upwards of 80 years before the right conditions allow them to hatch.

If your school hasn’t run the experiment yet, check out this video of the way they “jump” through the water!

So, what do Daphnia eat? Well, they’re herbivores! They eat phytoplankton, or “algae” that use the sun’s energy for photosynthesis. Phytoplankton come in all different shapes and colors, but they’re often GREEN.

Here is a picture of what I feed our colonies during the month! With a microscope, you can actually see their gut, which is clear, full of food. Daphnia are critical for controlling algal populations.

Phytoplankton can grow so intensely, they become known as an algal bloom. Check out these pictures in Owasko Lake (left) and Fall Creek (right). This can be exacerbated by human impact. Adding excess nutrients, such as fertilizer runoff or sewage/animal poop, have caused these blooms to worsen. Why is this bad?

• Harmful to human health

• Harmful to pet (including dog) health

• Depletes oxygen and kills fish and other organisms

• Blocks sun from reaching organisms deeper in the water

Daphnia are an amazing species. They are sensitive to pollution and, therefore, incredibly helpful in determining the health of a body of water.

Dapnia present? Healthy water! Daphnia are absent? Check out the water more.

This is known as an indicator species!

We might not spend the year studying daphnia, but they're helpful to learn about when considering the ecosystem for our trout. All of these factors come together to create a healthy habitat for us and the animals we live by.