Marine Miniature Ecosystem(s) Update #2 (A fast-paced update!)

Quite a lot has happened to the jar ecosystems since I last wrote. For one, the first ecosystem did not go as well as hoped.

As it turned out, there were a few more polychaetes than expected…as in, approximately five. I discovered them shortly after posting the first update.

There’s one now!

There were also two larger roundworms and several smaller worms that were extremely difficult to photograph!

One of the larger roundworms hanging out at the surface of the water.

Although I’d hoped to return the polychates to the ocean in the morning, there was unfortunately not enough dissolved oxygen for them to survive the night. After they died, the nutrient influx was massive and caused the ecosystem to collapse.

Some lovely nutrient sludge draped over rotting algae.

I still had another jar to fill with seawater, but I waited. My Marine Ecology course was starting in only a few days and I wanted my students to be involved in the jar creation process. In the best case scenario, our class jar would illustrate how ecosystems function and ecosystem processes. In the worst case scenario, it would illustrate how ecosystems are very difficult to get right and how we can learn from every experiment, regardless of whether it turned out correctly.

I polled the class and they decided to create the jar as follows:

  • With both coarse and fine sand
  • Water from “As far out into the ocean as Emma can reasonably wade”
  • Green intertidal algae and red intertidal algae
  • Mussel shell and a small rock as decorations

After a quick trip to the ocean, our jar was created!

A fresh start.

After a week and a half of slow deterioration, the class decided to add more algae and remake my first jar attempt with the same characteristics as before.

The algae in the class jar was looking a little worse for wear, but there were some signs of life–like this roundworm.

Back to the ocean I went. Once I returned, I rearranged algae and tried to aerate the jars a bit to get more dissolved oxygen in the water. My dorm room had definitely smelled better! I attempted to capture as much diversity as possible, since diversity generally increases ecosystem stability.

Old (2nd attempt) jar on the left, new jar on the right.

In exciting news for the class, our new jar had unknowingly brought home a new class mascot: a little nudibranch!

The class voted to name them “Peanut butter.”

Unfortunately, after a couple days, Peanut butter disappeared. We came to terms with the loss as a class with a moment of silence.

The original jar wasn’t doing well either, even with the addition of more algae. However, this was a great example of alternative ecosystem states for the class to learn from! It can be very difficult to push a jar ecosystem back into a different ecosystem state.

Fast forward a few weeks and both jars had seen better days.

(The jars were also moved home, since the quarter ended!)

Before moving back home for winter break, I noticed that there seemed to be a growing layer of white around the circumference of the jar. My students and I were very interested in what this could be, so I took a sample to school and took a look under the microscope.

Bacterial mat?
Lovely!

The consensus was bacteria, especially since I also saw paramecia (which feed on bacteria). There might be hope for life in these jars!

Today, the jars are doing about the same.

A picture after they’ve been stirred up a bit.

I’m looking forward to watching them as they progress in these alternative stable states!

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