… and the experiment started!

After a long preparation, mainly done by the Villefranche team, and some days of test samplings were we all learned how to deal with the ropes, the platforms, the hydrobios integrater sampler, pumps etc, each of us have already sampled for its own data. During this preparation we had some troubles (mainly in the windy days). For example, the pump used to acidify felt once in the water (luckily it was saved), one of the carrying boxes with all the empty bottles also felt in the water in a windy day, but after a refreshing swim it was saved as well. Some of the scientist also felt in the water but came back swimming and finally, one team was caught in pictures when, unlocked themselves from the mesocososm units and, taken by the currents, started to drift in the platforms… soon they were brought back by zodiac.

Sample team is brought back by boat after drifting with the currents. On the platform they were probably just enjoying the little trip 😉

All these experiences made us stronger and ready for the real samplings and subsequent processing of the samples. In my case it meant filtering about 80 liters of water. These because I want to see coccolithophores, marine calcifying phytoplanktonic organisms that are at the base of the food web and particularly sensitive to the changing ocean carbonate chemistry. Coccolithophores produce plates (coccoliths) of calcium carbonate which they use to cover their bodies (single cells).

For these organisms, a decreasing pH of the ocean is expected to affect the production of calcium carbonate by coccolithophores (see Image from Beaufort et al. 2011 article where evidence from sediment samples seem to agree this hypothesis). From each of the nine mesocosms I will be filtering 9 liters of water to later observe the filters under the scanner electron microscope (SEM). I will check whether those coccolithophores living in the more acidic ambient have more malformed, incomplete or thinner coccoliths than those living under normal conditions (in the Mediterranean “normal” means high alkalinity and saturation state for calcite, impeding the dissolution of calcium carbonate). Half of the water will be used to measure Ca in the smaller than 40um fraction (if I manage to get sufficient material). First samples are in the oven!

Modified from Beaufort et al. 2011

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