STEM Activity: Aquatic Biospheres


 

As a grand finale to our biology unit, we made desktop aquatic biospheres. The process that I will give links for in this post is for if you’re doing this for a large group (20 kids).  You can most certainly make one of these for your household even more easily than doing it for a large group.

Similar to the terrariums, we set this up assembly-line style and it went great. It’ has now been a couple of months and our biosphere is still going strong. We lost one snail, saw a bunch more be born and grow and our little shrimp is very much alive and well.

Materials

· A 1-quart glass mason jar (not plastic – plastic can leach chemicals into the water)
· Plastic containers for mixing and for a holding tank (we used Walmart utility buckets)
· Aquarium with aerator if you need to hold the live animals for a group project
· Tap water

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Aquarium used to hold live shrimp and snails

From an aquarium store:
· Aquarium gravel
· Tap water dechlorinator
· Glass or ceramic ornaments, seashells
· Freshwater minerals such as “Kent Freshwater” or “Cichlid Salts”
· Freshwater cleaner shrimp or similar (eats algae and can tolerate high pH levels)
· Two small snails (we used bladder snails)
· Eight stem inches hornwort or elodea
· Duckweed (Lemna) if you can find it
· One TBSP powdered calcium carbonate (primary pH buffer)
· Algae wafers (only if you need to feed the animals while waiting for group project)

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We used a couple of these to feed the shrimp and snails while we waited for the day to make the biospheres

From a local fresh water source or pond:

· Algae or water plants
· Pond water
· 1 to 2 TBSP pond sludge – should contain small animals, bacteria, and microalgae

Swansea Dam where we got our fresh water sample, algae and sludge

I unfortunately didn’t get pictures of the process, but essentially, we set up the tables so that the kids could fill up their jars with each material as they went along. The most difficult part for me (as organizer) was making sure I didn’t kill all the animals before we got to group. A local pet store was kind enough to let me buy some aquarium water along with the chemicals I needed to treat the tap water. I also had to keep the live plants submerged to keep them alive.
Helpful resources:

How to make a DIY Biosphere
Make’s Make a Tabletop Biosphere
Green Mom’s Do It Yourself Biosphere

Hope you make your own and send us some pictures!