Every mesocosm needs a hoody!

Installing a roof on a KOSMOS mesocosm Installing a roof on a KOSMOS mesocosm

In my opinion, our mesocosm only look complete with their hoody! Fortunately for me, a roof does not only serve an estathic purpose and we have to take the effort to install them before closing the mesocosm bags.

It rains a lot in Bergen. You might have heard about Bergen being Europe’s rainiest city? I didn’t believe it could be that bad, but one look at the weather forecast for the next days proves me wrong.

The weather forecast for the next days in Bergen

Weather forecast for Bergen

All this rain is not only inconvenient for the people going out by boat, it’s also an issue for our experiment. The determination of each mesocosm’s volume is crucial for many parameters and the budgeting in the end. But how do you measure the volume of a bag of this size? Simple in theory. You measure the salinity (saltiness) of the water, then add a tiny bit of highly saline water equally to the mesocosm bag and measure the salinity again. The change in salinity know gives you a pretty precise estimate of the volume in the bag.

What sounds simple in theory isn’t that easy in practice. I won’t go into detail here, but you might see already were this is going. Rain introduces freshwater to the mesocosms, and freshwater changes salinity. This means we need to protect our bags from rain to get a good estimate of their volume.

And how do we do it? We give them a little hoody! Additional spines avoid feathered guests who tend to leave small presents.

With the roofs installed, the mesocosms are ready to be closed know and finally look complete.


Pictures by Solvin Zankl