Anyone who owns an aquarium knows about Artemia, a fairy shrimp sold as fish food. What’s sold are dried cysts, which hatch when put in water. Many other animals lay such cysts as life history adaptations to living in temporary waters. It just so happens that I have two projects in such waters: the saline Akrotiri Lake and the freshwater Liopetri vernal ponds.
For the past several months, I have had two freshwater aquaria at home where I hatched cysts from some sediment from the vernal ponds. The experiment was a big hit, although I never did manage to get adult crustaceans (but there were plants, all sorts of naupliae and even worms, all hatched from the sediment).
But the experience gathered was valuable, and I’m now taking on a completely new challenge: hatching ancient sediment from Akrotiri Lake. These were obtained opportunistically: sometime last year, an idiot tourist drove into the lake and his 4X4 got stuck. Hijinks ensued, with rescue efforts also getting stuck in the mud, and a trench had to be cut to get all the vehicles out. Luckily, a geologist was at hand to take free samples which would otherwise have necessitated proper drilling and coring (and who’s going to pay for that?).
The picture above shows the five layers sampled, arranged from left to right from bottom to top of the trench (so oldest to youngest layers). I am using sediment from the surface and from the next oldest layer in order to test out different ways of hatching, so that I can guarantee success with the bottom (and most precious) sediments. Notice that the bags are open. This is on purpose, and should be done with all bags containing drought-resistant cysts, because there are certain asshole fungi that specialise on such cysts. Closing the bags allow them to flourish, for some reason. So keep the bags open to avoid contamination (paradoxically).
Above is all the equipment needed in order to do hatching experiments, in doubles because I have two aquaria. The containers are on the left. It’s important that they’re made of clear material (glass is the best), because at least the first few days need constant light. On their left you see the air pump and associated tubing, very important because these containers can get anoxic pretty quickly. On the sheet of paper are accessories for the pump: a splitter with adjustable valves to control amount of air, safety valves, and the bubble thingie. It’s important that you get the type that produces large bubbles, as the naupliae that will hatch will choke on small bubbles.
Pictured above is how to set up the splitter-safety-bubble combination. Before you set this up, it’s a good idea to prepare your nutrient water. Simply take a 1L bottle of water and add 25g of yeast. It’s not a precise science – yeast comes in 100g packets here, and I use ~a quarter of it each time. For a saltwater aquarium, make it saline with the salt you get in aquarium shops. Make sure that the salinity roughly matches the target environment (Akrotiri is not salty at all, so not much salt is required). If you’re a daredevil, you can put some sugar into the water as well – but keep in mind this carries a big risk of fueling the development of pond scum which you have to skim, at least until hardcore herbivores hatch (not guaranteed).
Anyway, once you have all that prepared, you put the sediment in your container, and place the air bubble thingie on top, then pour in the water. Don’t be afraid of stirring things up while pouring, it simply simulates rainfall. Pictured below is my complete set up. Notice the paper near the aquaria: keep those to write down any observation and timestamps.
For the first few days, the container will be turbid as the sediment slowly settles. Once it’s clear, you can add some more yeast, causing the water to become cloudy again. It’s a good idea to develop some sort of homemade visibility scale (put a bright object on the other side of the aquarium, for example), because the speed at which the container clears up from the yeast is a direct correlation with organismic activity inside the container.
If you have a source of cysts – temporary ponds are a good place to get them – I strongly suggest you start a similar hatchery. It’s not only fascinating (especially in this case, where the sediment is thousands of years old), but if successful, it’s an easy way to set up a microcosm and observe ecology directly in your bedroom.