The problem with Artemia storage
A familiar problem - I bought Artemia eggs, started them immediately and lo and behold, they hatched very quickly! Six months later, almost nothing hatches at all. And this despite the Artemia cysts being stored at 5°C in accordance with the instructions and all other parameters being adhered to as per the hatching instructions. What is the reason for this? How do you store Artemia eggs correctly?
Suppliers and specialist literature generally recommend a temperature below 10°C for the storage of dried Artemia cysts. What is important, however, is that Artemia eggs must be stored in an airtight environment, i.e. the eggs must not have any direct contact with the ambient air (Van Stappen 2003).
From a practical point of view, this is no longer the case once the pack has been opened. The often very dried Artemia cysts come into contact with oxygen and moisture. Both parameters can trigger biochemical processes in the Artemia cysts and reduce their shelf life (Clegg & Cavagnaro 1976). The problem is exacerbated if a pack of Artemia eggs is opened briefly on a warm summer's day and then closed again and placed in the refrigerator. This allows air with a high moisture content to enter the pack. This moisture then condenses into a very small amount of water in the refrigerator, enough to significantly accelerate the decay of the Artemia eggs!
How do you store Artemia eggs?
From a practical point of view, we therefore recommend that our customers store the Artemia cysts in an airtight freezer at -10°C to -20°C. This is the only way to ensure that the high hatching rate is fully maintained over a longer period of time. If you are storing a large quantity of Artemia cysts, it makes sense to divide the Artemia eggs into several airtight PET tins. This prevents all the eggs from being defrosted each time they are removed and prevents too much moisture being drawn in.
Sources
Clegg, J.S. & Cavagnaro, J. 1976 Interrelationships between water and cellular metabolism in Artemia cysts IV. ATP and cyst hydration. J. Biophys. Biochem. Cytol., 88, 159-166.
Van Stappen, G. 2003. Production, Harvest and Processing of Artemia from Natural Lakes. In: Stottrup J.G., McEvoy L.A. (Ed.).Live feeds in marine aquaculture. Blackwell Publishing Ltd, Oxford, S. 122ff
