Primary production and carbon export across the Flamborough frontal system: interaction with offshore wind energy

Project Description:

The Project

In this proposal, the PhD student will use existing North Sea wind farms as examples of how modification in vertical stratification in the near and far-field may manifest in altered phytoplankton exposure to sunlight and nutrients, and hence change growth rates and productivity.

Along with the rapidly growing offshore renewable energy industry, the fisheries and tourism sectors are an important part of the UK coastal economy, and are underpinned by a healthy and productive marine ecosystem. However, concerns have been raised by regulators in relation to the impact of large offshore windfarms on productivity of coastal features.

Primary production at the base of the food web (e.g. formation of organic carbon via photosynthesis of phytoplankton, seaweeds, seagrasses and microphytobenthos) is critical in supporting marine biodiversity and fishery catches. Phytoplankton are of major importance in North Sea primary production as most of the seabed lies below the photic zone, hence limiting growth of attached benthic algae.

Initial work to model phytoplankton primary productivity has shown importance differences in phytoplankton bloom magnitude and timing for different regions of the north-east coast of England. The amount of phytoplankton productivity within a given season is known to be dependent on ocean mixing processes, and the stability of the water column. An early onset of surface water warming (stratification) is likely to produce higher productivity and a greater drawdown of carbon dioxide. Marked differences in the sea surface temperature with gradients of 5°C or more can be found along a north-south transect off the coast of NE England. This indicates the presence of discrete water masses with different levels of turbulent mixing in accordance with tidal flow, depth and wind speed. Understanding the location of transitional zones between well-mixed and stratified zones (e.g. frontal regions, such as the Flamborough Front) is needed to predict current and future levels of phytoplankton production, and possible changes in mixing due to interaction of tidal flows with artificial objects such as offshore wind farms must be taken into consideration.

Training and Skills

The successful applicant will receive training in oceanographic techniques at sea, underwater optics, measurements of phytoplankton physiology using active fluorescence, and processing and analysing satellite remote sensing images. The PhD and its training will provide an excellent background for a career in applied marine science in the offshore renewable sector or governmental agencies.

References:

Capuzzo, E., Lynam, C. P., Barry, J., Stephens, D., Forster, R. M., Greenwood, N., Mcquatters-Gollop, A., et al. (2018). A decline in primary production in the North Sea over 25 years, associated with reductions in zooplankton abundance and fish stock recruitment. Global Change Biology, 24, 352364.

Daewel, Ute, et al. “Offshore Wind Wakes-the underrated impact on the marine ecosystem.” (2022).

Floeter, J., van Beusekom, J. E. E., Auch, D., Callies, U., Carpenter, J., Dudeck, T., Eberle, S., et al. (2017). Pelagic effects of offshore wind farm foundations in the stratified North Sea. Progress in Oceanography, 156, 154173. Pergamon.

Lawrenz, E., Silsbe, G., Capuzzo, E., Yl?stalo, P., Forster, R. M., Simis, S. G. H., Pr??il, O., et al. (2013). Predicting the Electron Requirement for Carbon Fixation in Seas and Oceans. PLoS ONE, 8(3).

Moore, C. M., Suggett, D. J., Hickman, A. E., Kim, Y. N., Tweddle, J. F., Sharples, J., Geider, R. J., et al. (2006). Phytoplankton photoacclimation and photoadaptation in response to environmental gradients in a shelf sea. Limnology and Oceanography, 51, 936949.

Scott, B. E., Sharples, J., Ross, O. N., Wang, J., Pierce, G. J., & Camphuysen, C. J. (2010). Sub-surface hotspots in shallow seas: fine-scale limited locations of top predator foraging habitat indicated by tidal mixing and sub-surface chlorophyll. Marine Ecology Progress Series, 408, 207226.

Wihsgott, J. U., Sharples, J., Hopkins, J. E., Woodward, E. M. S., Hull, T., Greenwood, N., & Sivyer, D. B. (2019). Observations of vertical mixing in autumn and its effect on the autumn phytoplankton bloom. Progress in Oceanography.