IMEDEA develops new technology to study super-coherent structures in oceans and their impact on diatom production

14/09/2023

A research group at the Mediterranean Institute for Advanced Studies (IMEDEA, UIB-CSIC) has developed technology to identify super-coherent structures in ocean currents and their impact on diatom production.

IMEDEA-UIB-CSIC researchers Ismael Hernández-Carrasco and Alejandro Orfila have led a project to develop a methodology to identify super-coherent structures in Mediterranean currents. These clearly defined geometrical structures are highly intense whirlpools and fronts lasting longer than a month that can measure over 100 km. The research aimed to analyse how these structures impact the production of diatoms, essential organisms for life on Earth.

 

The relevance of studying diatom proliferation

Marine diatoms are some of the most abundant phytoplankton and play a major role in the oxygen cycle and removing CO2 from the atmosphere. These organisms tend to grow in nutrient-rich environments, such as the polar regions or coastal blooms. However, their abundance is predicted to decline due to increasing ocean stratification as a result of global warming.

Understanding the physical processes behind diatom proliferation is key to accurately predicting future primary production and carbon export.

By using satellite imagery on ocean colour and currents, alongside numerical modelling, the study has demonstrated how physical conditions driven by these super-coherent structures boost diatom bloom, even in oligotrophic, stratified environments (i.e. areas where available nutrients offer little to sustain life).

The study stems from the solid research undertaken by Alejandro Orfila and Ismael Hernandez-Carrasco over several years on different projects in the field of physical oceanography from a perspective of non-linear physics, such as TRIPTOP, ALERTA and LAMARCA. Moreover, they collaborate closely with other national and international research teams in France and the United States.

Fig. 1: Normalised diatom abundances, P(diatoms), as a function of the time integration T found in regions of high negative ΩT (panel a); high positive ΩT (panel c); high KT (panel b), and finally both high negative ΩT and high KT simultaneously (panel d).

 

A future gateway to diatom research

 

Current global estimates of diatom-associated biological production are not particularly accurate, since they are limited by the low resolution in satellite imagery and most coupled physical-biogeochemical modelling.

The study’s findings open up new avenues for more accurate estimates of diatom distribution and production in the near future.

 

Information about the article:

Hernández-Carrasco, I., Rossi, V., Navarro, G., Turiel, A., Bracco, A., & Orfila, A. (2023). Flow structures with high Lagrangian coherence rate promote diatom blooms in oligotrophic waters. Geophysical Research Letters, 50, e2023GL103688. https://doi.org/10.1029/2023GL103688