Testing dust-fertilisation in the lab!

Coccolithophores are a group of unicellular marine phytoplankton living in the photic zone of the ocean and drifting with the currents. Like any other marine algae or terrestrial plant, they need light and nutrients to perform photosynthesis and grow, using atmospheric CO2 and releasing oxygen during the process. By doing so, marine phytoplankton profoundly affects important global biogeochemical cycles and climate, being responsible for producing most of the Earth’s oxygen (e.g. Thomas et al., 2012) 

 Illustration of marine phytoplankton (including coccolithophores) drifting in the ocean (organisms are not to scale). Image obtained from: https://www.youtube.com/watch?v=jsgCjgcp_6g

Illustration of marine phytoplankton (including coccolithophores) drifting in the ocean (organisms are not to scale). Image obtained from: https://www.youtube.com/watch?v=jsgCjgcp_6g

Since desert dust transported by the wind is known to carry nutrients and trace metals that are essential for photosynthesis, dust has the potential to act as a fertiliser for marine phytoplankton in regions of the global ocean that are nutrient-depleted, with possible implications for marine biogeochemistry and atmospheric CO2. To investigate this issue, we are preparing a coccolithophore batch-culture in which we will use dust samples collected from the Saharan desert pre-adjusted to resemble dust that is naturally deposited in the ocean and leached in acidified ‘artificial rainwater’ (H2SO4) for mimicking acid cloud processing. Our experiment is inspired in an incubation led by Laura Korte on board RRV James Cook, during our last transatlantic expedition (March/April 2016). 

 Incubation experiment for testing the effects from dry- and wet-dust deposition on the tropical North Atlantic led by Laura Korte during the expedition JCR134 on board RRV James Cook (March/April 2016).

Incubation experiment for testing the effects from dry- and wet-dust deposition on the tropical North Atlantic led by Laura Korte during the expedition JCR134 on board RRV James Cook (March/April 2016).

The coccolithophore culture is being prepared at MARE’s Algoteca under the supervision of Ana Amorim, a marine biologist at MARE and full professor at FCUL, and guidance by Bernardo Vicente and Luísa Dâmaso both working at MARE. Bernardo is a MSc student working in the lab and is about to finish his thesis focused on the role of SiO2 for cell production and calcification of Coccolithus pelagicus. With his help, we have started culturing Emiliania huxleyi – probably the most opportunistic of the coccolithophores species that we know – but hope to culture other species as well, in the future. We will keep you updated on our progress!!! 

 Catarina, doing her very first mono-culture of  Emiliana huxleyi  in the lab!

Catarina, doing her very first mono-culture of Emiliana huxleyi in the lab!

 Viewing inside one of the phytoplankton culture-chambers existing at Algoteca. Each of those vials and petri-dishes contain millions of living cells of mono-cultures of phytoplankton. Species are maintained under controlled conditions of temperature, light intensity and nutrient concentrations. Regularly, all of these cultures representing different species have to be changed into new culture medium with fresh nutrients to keep the microalgae alive and healthy.

Viewing inside one of the phytoplankton culture-chambers existing at Algoteca. Each of those vials and petri-dishes contain millions of living cells of mono-cultures of phytoplankton. Species are maintained under controlled conditions of temperature, light intensity and nutrient concentrations. Regularly, all of these cultures representing different species have to be changed into new culture medium with fresh nutrients to keep the microalgae alive and healthy.

 This is Bernardo showing us how the work is done. Thank you Bernardo, for you guidance and patience while explaining us all the procedure!

This is Bernardo showing us how the work is done. Thank you Bernardo, for you guidance and patience while explaining us all the procedure!