Understanding the mixing generated by zooplankton

How to measure a Daphnia

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📥  Zooplankton

One of my biggest problem in the past weeks was measuring the size of Daphnia we have in Vobster Quay. That's very important to understand how they can affect the mixing during the vertical migration and their life stage. Daphnia usually live for 2 months reaching the maximum body length. So different sizes means different ages.

Unfortunately the microscope I have in the Water Quality Lab @UniBath in Civil Engineering wasn't that powerful and even using my Snapzoom microscope adapter didn't help that much. The image was too blurry and I couldn't use even the ruler!


Leica microscope from Elec-Eng


My microscope


So Gianluca showed me the big microscope he sometimes uses in Electrical Engineering. After going through risk assessment and authorisations, I managed to take some nice shoots of my samples. This is a  monster compared to my tiny microscope (which still does the job for what I need to do!). It directly saves picture from the built-in camera as well.

And there they are!

Image of zooplankton from one of Vobster's samples


The size of Daphnia (red lines) is measured from the eye up to the beginning of the tail. For copepods (blue lines) from the head to the end. Most of Daphnia and copepods have a maximum size of 1mm which a common value. Other samples in different days may have bigger organisms, so stay tuned for the next shots!

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