Elliot, Jacob and I (mostly Elliot and Jacob…) have been hard at work on the new aquarium facility. After rinsing and soaking the tanks in deionized water (to get rid of chemicals used in manufacture, dust particles, and other gunk!) the two holding tanks, quarantine tanks and experimental tanks were moved to the coldroom. These were filled with artificial seawater (Instant Ocean) and their filtration was set up. Because sea stars are incredibly messy – they exude copious amounts of goo – we need a LOT of filtration, hence we’re using three filter mechanisms to keep the tanks clean: 1) biological filtration via biowheels; 2) cannister filtration; and 3) UV light sterilization. In addition, for the first two weeks of the project we will be replacing 40% of the water volume in each tank (that’s a whopping 65 gallons) with fresh artificial seawater per day. After 2 weeks we’ll probably lower this down to every 2 days.
Our Quarantine Tank – a 75 gallon monster!
A key part of biological filtration is that it’s biological – meaning bacteria (and archaea) are used to perform essential aquarium services of removing ammonium (which is toxic) and making it into harmless nitrite and nitrate via the process of nitrification. In some systems, bacteria are also used to remove nitrate and nitrate into gaseous nitrogen gas via denitrification. The latter process is anoxic, so it can take a bit of time for biofilms to develop that allow this to happen. Both processes don’t happen unless there is an inoculation of bacteria into the tanks. Where do we get our bacteria? From marine animals of course! Where do we get marine animals in central New York? Our local supermarket, Wegmans of course.
We’ve put 10 or so mussels (aquacultured from the North Atlantic Ocean) into each aquarium to seed our biological filters with beneficial bacteria. The mussel’s microbiome is astounding – there are literally thousands of species of bacteria and archaea that live on and within mussel tissues, shells, etc. Now most of these are harmless to humans who eat them, since they’re cooked. And even raw oysters are usually OK, since most bacteria inhabiting them are not pathogenic (i.e. disease-causing) to humans. But they do serve as a useful reservoir of nitrifying and denitrifying bacteria for our aquaria!
You’re probably also wondering, once our sea stars arrive, what we will feed them. Since sea stars tend to be rather fastidious when they first arrive in a new setting (I’m fastidious after traveling for 26 hrs too…), we’ll be feeding them small bits of wild-caught shrimp. The two species of sea stars we’re working on, Pycnopodia helianthoides and Evasterias troscheli aren’t particularly picky when it comes to food; in fact, P. helianthoides will eat pretty much anything. So, over time we may change their diets to mussels like these.
Finally, our experimental tank design is coming along. Soon we will have contained and independent replicate tanks in which we will try and infect the animals and observe their microbiology and gene expression.
So things are coming along nicely. Next week (Friday) we head to Alaska to sample the stars and see what we can see. Stay tuned!