Daphnia Shenanigans

Daphnia Shenanigans: A poem outlining my efforts to measure the effect of temperature on trophic interactions in freshwater systems


Metabolic theory states

That temperature affects all vital rates


From feeding to reproduction

Temperature generally ramps up production


But what does this mean for ecosystems?

Does this make biological communities temperature’s victims?


Or do we see an increase in diversity?

Greener spaces and higher productivity


What did temperature do to my little jar ponds? Photo credit: Myself


This is the question I would like to answer

For our global climate is warming faster and faster


With IPCC projecting temperature rises of up to 4 degrees

This will have consequences for our global lakes, oceans, and seas


The organisms that call these places their home

Interact in what we could call the aquatic biome


Phytoplankton are the key primary producers

That use light energy to make food for all other consumers


Zooplankton will come along and eat these algal cells

They use the energy to reproduce and their populations grow in large swells


The zooplankton provide food for the animals like fish

Full of fat and omega 3s they really are a tasty dish


These interactions are what make the global ocean function

But temperature can affect how these populations grow in conjunction


Due to a variance in thermal ranges, certain organisms are more sensitive to heat

Higher temperatures can cause only a subset of the community to admit defeat


The animals that persist will continue to grow

Until their population crashes and after that we don’t know


By growing organisms separately and in unity

And manipulating temperature for individuals and the whole community


My trophic treatments from left to right: Jar 1: Algae, Daphnia, and a Daphnia predator, Jar 2: Algae and Daphnia, Jar 3: Just algae. A refuge was placed in the treatment with a predator to give the Daphnia a place to hide. Photo credit: Me!


We can see how temperature effects species interactions

Through how populations and species display their reactions


This is why I warmed three trophic levels each in their own cup

To see if the populations, of daphnia or phytoplankton or both went down or up


I found that temperature had an effect on algae population size

And Daphnia reduced the algae present: they really are hungry guys


At 20 degrees algae grew best

But at 16 and 24 the algae growth took a rest


This could mean 20 degrees is an optimal temperature for this phytoplankton’s population

Allowing them to grow better and faster through asexual replication


With Daphnia population we saw no clear trend

There was a high degree of variation, indicating the effect of temperature could depend


On how healthy the daphnia were at the start of the experiment

Or whether they were pregnant, big and how many babies were present


Daphnia are some of freshwaters ecosystems key players

And when we’re warm we can just shed off some layers


But Daphnia have no way to adjust their body to temperature change

And this can cause their enzymatic activity to rearrange


The entire Daphnia population in a jar. Look how cute they are! Who took his amazing photo? You guessed it: Joey Bernhardt


This will affect their ability to reproduce

And their size upon reproduction will likely reduce


With increasing temperature I predicted a reduction in Daphnia population size

But due to the high degree of variation I cannot say if there was a reduction or a rise


So in order to explore the effect of temperature on zooplankton and see the differences I seek

I need to follow their changes in population for more than a week


But alas it was sweet time that lead me astray

I thought I had more to get my Daphnia sampling out of the way


So while I didn’t get all the data to see some clear trends

I still had lots of fun with my zooplankton friends



The metabolic theory of ecology has left me with questions so abound

It was fun to design an experiment to see what designs work and which ones weren’t sound


I enjoyed designing and excecuting this experiment

This class was so fun it seemed that it just came and went


In biology 326 I learned a lot about how to manipulate invertebrates

From running stats to the right number of replicates


Thanks to Chris Harley and my TA’s Matt and Kat

You guys were fun, helpful, and supportive, a trio of class acts


To all my fellow students I will miss our scientific investigation

I know a few of you are almost done with your post-secondary education


So best of luck with life and all the adventures that your future entails

And please never forget the potential effects of rising CO2 on snails :D.




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