The soup tastes better with a bit more salt

Take a look at our delicious soup-salting party yesterday night in the fjord…

With this giant spider, Sebastian, Jan, Signe, Kai and me are improving the taste of the soup in the mesocosms !

The “spider” is made of many small tubes able to diffuse salt-enriched seawater in the mesocosms and to mix it well. The same spider will also be used to add CO2 to the water when the manipulation will start. This strange animal is necessary to ensure that the salt is really well mixed everywhere in the mesocosms- if we would just pour it all at once, since it’s heavier than the normal seawater it would just sink and stay at the bottom.

We put the spider inside the mesocosms, switch on the pump to pour salted water, let it sink to the bottom and then pull it up, sink again and pull again- about 10 times in a row, quite heavy and exhausting! –  to allow the additional salt to be well mixed in the whole column.

This operation will give us a crucial indication: the exact volume of the mesocosms. It may vary significantly from one to another, depending e.g. on the way the plastic bags unfolded in the water, and we need to know it acurately to be able to make comparisons between the different mesocosms. Salt is just a trick for that: we first measure the salinity of the water, then know exactly how much salt we add, then measure again the salinity- and from the difference we can deduct the precise volume of the cynlinder.

It’s past midnight when we return to the harbour, but Jan is the happiest guy on Earth- this was the first outing for his spider and it did not break any single leg.  Happy salty spider on its fjord-wide web!

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