This update is part of our ongoing experiments to monitor nutrient update (N-P nutrient remediation) using tank cultivation of free-floating Ulva (seaweed macro algae).  Throughout this experiment our team monitored the changes in biomass by weight of algae every two weeks to see if they have grown or degraded. Water samples were taken monthly and sent to our partners at University of Caen (UCN) to measure changes in nutrient concentration, which is also an indication of nutrient update or chemical changes in the cultivation tanks. Photosynthesis activity is also measured, and the data collated for analysis.  For each tank, algae samples are collected at the start and end of the experiment and processed by drying to analyse the tissue contents. We have lots of processed algae tissue data for analysis so stay tuned for the results.

Picture of the Ulva seaweed cultivation tanks (crédit : ALEOR) 

Ulva under the microscope

An important part of our study is differentiating the Ulva algae species. To differentiate between Ulva species, they are observed under a microscope. To do this we make dissections into the leafy tissue, to observe the algae from different points of view and magnifications.

Our team are using a 2-step process. At first, small sections of Ulva are laid flat to study the edges that will provide the first type of clue in the differentiation. In the photo below, there are small tooth-like (circled in red) features on the edges of the Ulva seaweed, which is very specific to a specie.

Photo of an Ulva blade under the microscope (circled in red, the teeth) (Crédit : Aleor) 

In the second step, we make a so-called transverse section (dissection in the thickness) of the tissue. This allows us to observe the interior of the algae, more precisely the organisation of the cells. In the photo below, is a cross section of the Ulva from the cultivation tanks showing a bi-stromatic blade. We know that we have a bi-stromatic blade because under the microscope, cross-sections of the algae show two rows of cells.

Thanks to these two microscopic observations, we can determine that the species of algae is Ulva rigida. Stay tuned for more results!

Merci Inès (Société Aleor)

Photo of a cross-section of an Ulva blade (each red arrow denotes a row of cells) (Crédit : ALEOR) 

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