About My Science

I'm a marine biogeochemist and plankton ecologist. My research is focused in understanding the relationship between the distribution of nutrients and dissolved oxygen in the sea and the elemental composition of phytoplankton.

To study the elemental composition of plankton, I have developed a method to determine the single-cell elemental composition of microphytoplankton (mainly diatoms and dinoflagellates) using X-ray microanalysis (XRMA) in scanning electron microscopes (SEM). This technique allows the simultaneous identification and quantification of not only the most important elements in marine ecology, C, N and P, but also the O, Mg, Na, Al, Si, S, Cl, K and Ca that are present in single natural cells. I have focused on diatoms and dinoflagellates, because they have an important role in marine primary production, as well as they are the main contributors to the organic matter export from the surface ocean, and hence, affecting the nutrient composition in deep waters. Dr. Dolors Blasco was the my main PhD advisor at the Institute of Marine Sciences in Barcelona (Spanish National Research Council), but I had also the good luck to enjoy some months in the University of Bergen (Norway), where Drs. Mikal Heldal and Svein Norland taught me how to quantify the elements present in single cells.

Because changes in plankton elemental composition and stoichiometry are related to environmental conditions, which determine the availability of nutrients and light to the phytoplankton, I am also interested in the study of dissolved inorganic and organic nutrient distributions in the sea. During my PhD I made a climatology of nutrients, chlorophyll a and dissolved oxygen of the Catalan Sea (NW Mediterranean Sea) using 20 years of oceanographic cruises data. First, I used this data to define the ranges of concentration to quality control data from the Catalan Sea. Then, I used quality controlled data to describe nutrients and dissolved oxygen dynamics in the Catalan Sea, including the description of seasonal variations and interanual trends. Finally, I studied the relationship between nutrient and plankton stoichiometry, according to the Redfield theory. Following this line, after my PhD dissertation I was fortunate to join Prof. Burke Hales group in Oregon State University, where I learnt about the chemistry of the carbon in the sea and used a high-frequency instrument to determine nutrients and carbon in upwelling areas. In Burke's lab I discovered my passion about handling nutrient instruments more than at user level, and so far I have tried to implement in the labs I worked in the most up-to-date methods and instruments, with highest sensitivity and lowest detection limits when possible, like the adaptation of a liquid waveguide capillary cell (LWCC) to the analysis of ammonium, nitrite and urea for the study of nitrification in the North Pacific Subtropical Gyre, during my postdoc stay at Prof. Karl lab, at the Center for Microbial Oceanography: Research and Education of the University of Hawai'i.

At that moment I'm a Marie Sklodowska-Curie Fellow at the Department of Chemical and Biological Engineering of The University of Sheffield, UK. I'm working on the widening of the use of XRMA in phytoplankton key groups, focusing on species of interest for biofuels production, as well as gathering more single-cell data in sea samples from the Western Channel, in collaboration with Plymouth Marine Laboratory.


Maria del Mar Segura i Noguera

At the Oregon coast