Up, up and away – the fate of upwelled nutrients in an African upwelling system and the biogeochemical and phytoplankton response

Dr Peter Brown, Dr Edward Mawji, Dr Elisa Lovecchio, Mark Moore, University of Southampton; Sarah Reynolds, University of Portsmouth
Rationale: 

The Canary Current upwelling ecosystem constitutes one of the four main eastern boundary upwelling ecosystems in the world. Hosting local high productivity and socioeconomically-important fisheries, it also plays a key role in transferring biogeochemical properties from the coastal upwelling eutrophic region towards the interior oligotrophic subtropical gyre, where the strength of the biological carbon pump is strongly controlled by the bioavailability of macro-nutrients. Recent observations indicate that the region as a whole has been experiencing a progressive warming, with an accompanying decrease in productivity over the last decades, potentially due to changing nutrient supply. A lack of systematic information on the regional variability of physical and biological processes that sustain ecosystem productivity hampers our understanding of how it will respond in the future. This project proposes a combination of new in situ high resolution autonomous biogeochemical observations with laboratory analyses of ecosystem activity and model-based understanding in relation to environmental forcings (e.g. productivity, circulation patterns, biogeochemical processes, etc.) which will allow for a better understanding of the nature and impacts of these interactions on the nutrient transport and ecosystem response of the upwelling system.

Methodology: 

The student will generate new observations and combine with novel datasets from multiple sources. They will work with the first outputs from biogeochemical sensors deployed on moorings at the eastern boundary of the North Atlantic subtropical gyre. These will provide a step-change in our understanding of the physical and biogeochemical variability and drivers of local ecosystems over multiple timescales (diurnal/weekly/monthly/seasonal/interannual). Laboratory analyses of water samples collected from the region on mooring recovery cruises will be used to interrogate ecosystem function and nutrient dynamics in the upwelling waters and cold-water filaments emanating from the shelf.

For temporal and spatial context (horizontal and vertical), comparisons will be made to historical hydrographic data, to local open-ocean observatories and gliders (PLOCAN-ESTOC), satellite-derived products and high-resolution biogeochemical model outputs (CLASS programme NEMO-MEDUSA 1/12°). Together these will put laboratory results sensor timeseries into a wider context, informing on how the shelf connects to the open ocean, what the controlling processes of slope biogeochemistry are, and their sensitivity to climate change and ocean acidification.

The ultimate direction of the above topic will be led by the student, who will be able to participate and contribute to the full range of activities associated with marine biogeochemical research (fieldwork, laboratory, sensors, autonomous platforms, models).

 

Location: 
NOC
Training: 

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at NOC/University of Portsmouth, each globally-renowned centres of excellence for biological carbon research. Specific training will include: field sampling and experimental design; operation of autonomous biogeochemical sensors and the analysis of their datasets; laboratory measurement and interpretation for inorganic and organic nutrients and carbon, and microbial community structure and function; statistical analysis and handling of high-resolution modelling output; programming languages for data analysis (Matlab/Python). As the project is highly multidisciplinary applications from candidates with diverse experience are welcomed. You will present your work (inter)nationally and there will be seagoing fieldwork opportunities.

Eligibility & Funding Details: 

Please see https://inspire-dtp.ac.uk/how-apply for details.

 

Background Reading: 

Landolfi, A., Oschlies, A., & Sanders, R. (2008). Organic nutrients and excess nitrogen in the North Atlantic subtropical gyre. Biogeosciences, 5(5), 1199–1213. https://doi.org/10.5194/bg-5-1199-2008

Arístegui, J., Barton, E. D., Álvarez-Salgado, X. A., Santos, A. M. P., Figueiras, F. G., Kifani, S., et al. (2009). Sub-regional ecosystem variability in the Canary Current upwelling. Progress in Oceanography, 83(1–4), 33–48. https://doi.org/10.1016/j.pocean.2009.07.031