Productivity regimes and plankton community in the upwelling system of the Azores

Phytoplankton production and its ability to fix and export carbon dioxide (CO₂) to depth is influenced by the available source of nitrogen (N) in the system. Assimilation of a new source of N, such as nitrate supplied by below the euphotic zone, fixes atmospheric CO₂ and leads to “new production”, while assimilation of a recycled source of N such as ammonium leads to “regenerated production” with minimal or no CO₂ fixed. Stable isotope (SI) analyses of nitrogen (N) and carbon (C) have been used extensively to study marine food webs with the δ¹⁵N of organic matter being an indicator of the trophic position of consumers in a food chain, while the δ¹³C of organic matter provides insights into the food source assimilated by a consumer. Changes in the primary production, species composition and biochemical composition of phytoplankton will likely shape the zooplankton community, via their influence on the food quantity and quality for different zooplankton taxa.

In this project we aim to i) identify the main N source assimilated by phytoplankton, ii) quantify primary productivity in the studied region, iii) investigate the relationship between the stable composition of phytoplankton and zooplankton.

The student will be analyzing samples collected during a cruise in the Azores in 2024 for flow cytometry analyses and stable isotope analyses of particulate organic N and C, as well as for N and C uptake rates and zooplankton. 

Requirement

This student will be based at the Department of Coastal Systems of NIOZ located in Texel for the duration of the project, which is expected to be 6 months starting in January-February 2025. This project will have a laboratory component for sample preparation and analysis using a flow cytometer and a mass spectrometer both housed at NIOZ, and a data handling component post analysis.

Contact

If you are interested in the project you can contact Dr Eleonora Puccinelli (eleonora.puccinelli@nioz.nl).