‘Cutting-edge’ science in Cambridge

CACHE researcher, Kati Michalek, give a scientific account of some of her research:

“Recently, I made my way from Oban in Scotland to Cambridge, catching up with my friend and CACHE fellow Luca Telesca for an exciting shellfish calcification experiment. Calcification rates of bivalves have been studied rigorously in the last decades, whilst almost exclusively being assessed in manipulative laboratory studies. Even though providing valuable insights into variations in the calcification response with changing environmental conditions, the experimental set-ups often restrict conclusions to be made about their response in the natural environment, i.e. where shellfish is cultivated. Therefore, a study has been designed which will deliver estimates about the calcification response (potential shell dissolution) in mussels cultivated on long lines in a Scottish sea loch.

Luca preparing a shell

I travelled to Cambridge with shell pairs of blue mussels, <Mytilus edulis>, I have been collecting throughout the year on a mussel farm on the Scottish Westcoast from four different depths (1, 3, 5 and 7m). With these shells we are aiming to estimate the calcification rate as well as the potential shell dissolution of mussel shells in their cultivation environment. Here, Lucas knowledge and expertise in shell morphology and microstructure have been crucial in order to achieve the best sample set-up and preparation. As indicated by the title, we “cut edges” (10×15 mm tiles) out of one shell valve of each shell pair, after gently removing the acid resistant periostracum.

Afterwards each tile has been embedded in a block of resin and polished in order to expose the shell’s calcitic layer to the environment. This procedure has been repeated for a total of 60 samples, originating from four different depths on-site the mussel farm respectively.

5.Fig 2 Kati in the lab

Kati in the laboratory

Back at SAMS in Oban, the tile blocks and blank blocks (=no shell tile) have been dried for four days at 40°C. Finally, I took them back to the mussel farm and deployed them at their respective depth of origin by attaching them on the inside of prepared sampling bags. The calcitic layers will now be exposed to the natural environmental fluctuations for a period of 3 months. Any loss in weight will be recorded, resulting in an estimate of shell dissolution at known environmental conditions. This estimate can be further used to correct the calcium carbonate amount assessed using the second shell valve.

5.Fig 3 Tile deployment on farm

Tile blocks.

This experimental design will give us insight on calcification rates of cultivated Scottish blue mussels directly encountered in their cultivation habitat. In addition, potential differences in shell calcification/dissolution with different depths can be discussed in the light of varying environmental conditions (reference to long-term monitoring on-site in progress, recording fluctuations of e.g. temperature, salinity, chlorophyll a, pH over time and depth). For example, shells form low pH habitats are thought to possess weaker shells with lower calcification rates and potentially higher risk of dissolution. Thus the data generated will be of high interest for the shellfish aquaculture industry in order to evaluate the performance of the mussel product in changing environmental conditions.”

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