A blooming ocean

Latitude: 61°30′ N
Longitude: 011°00′ W
See latest position
Waveheight: 2.5 meters
by Mario Esposito onboard the FS METEOR

The reason we measure dissolved nutrients is because, together with light, they are the key ingredients for a blooming ocean. And a blooming ocean absorbs vasts amounts of carbon.

Photoautotrophic organisms (plants) use sunlight as their source of energy to incorporate nutrients. Using inorganic substances, they are at the bottom of the food chain and consequentially necessary for all high trophic levels.

When the ocean blooms, the chlorophyll in the microscopic but numerous cells can be detected by satellite-borne sensors. But these beautiful images only show what happens in the surface.

Measuting dissolved nutrients below the surface can serve as an indicator of the state or the progression of phytoplankton blooms in situ. When algae grow they consume nitrate (NO3), Phosphate (PO4) or Silicate (Si), depleting the pool of nutrients in the upper layer.

For example, diatoms form shells mainly made of silicate, therefore a decrease in dissolved silicate concentration is a good indicator for a higher diatom production, which are a major taxon in the spring bloom.

To speed the process, we use light to mease nutrients. A reaction of prepared reagents with the nutrients induces a change in colour which can be accurately measured using a photometer. The intensity of the resulting colour accuratley inducates the concentration of the nutrient in question.

The cramped conditions at the nutrients lab onboard the FS Meteor. Mario Esposito, NOC

Additional resources:
Lesesson plans:
Seasonality in the ocean (K9-12) by COSEE NOW, link
A green ocean: Follow the Bloom (K9-12) by COSEE NOW and Ocean Gazing, link
Chlorophyll a from space (K9-12) by COSEE NOW and Ocean Gazing, link
The carbon Cycle Game (K9-12) by COSEE NOW, link


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