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John Gittings

How do identified climate change impacts on the oceans affect ecosystem services, including phytoplankton production and fisheries?

John studied Marine Biology and Oceanography at the University of Plymouth (United Kingdom) (2011 – 2015). During his time in Plymouth, he completed a one-year internship as a research assistant at Plymouth Marine Laboratory, where he developed a keen interest in ocean colour remote sensing and its applications for biological oceanography. Between 2015 and 2021, John attained both his MSc and PhD in Marine Science from King Abdullah University of Science and Technology – KAUST (Kingdom of Saudi Arabia). His PhD research primarily focused on how the timing (phenology) and community structure of seasonal phytoplankton blooms in the Red Sea may be changing in relation to the regional physical environment and the broader climate regime. John joined the Oceanography & Earth Observation Group at the National and Kapodistrian University of Athens – NKUA (Department of Biology), as an ESA Living Planet post-doctoral fellow.

Research objectives

The POSEIDON fellowship aims to understand the response of ocean ecosystems to climate warming and extreme events (e.g., marine heatwaves) using a novel, multidisciplinary approach by integrating contemporary oceanographic datasets, including satellite remote sensing observations, in situ cruise data and Biogeochemical Argo (BGC-Argo) floats. Specific research objectives include:

  • to regionally-tune and validate existing algorithms for computing phytoplankton ecological indicators (biomass, phenology and size structure) using a combination of remotely-sensed and available in situ datasets in several case study regions of the global oceans.
  • to construct an atlas that describes the spatiotemporal distribution of extreme heating events (marine heatwaves [MHWs]) within the regions of interest through application of a marine heatwave detection algorithm on long-term SST data (ESA SST-CCI).
  • to investigate the response of ecological indicators in identified MHW hotspots using remotely-sensed datasets.
  • to elucidate the impacts of climate change on ecosystem structure through a combination of statistical analysis and metabolic theory (e.g., biomass size spectrum modelling) that describe relationships between phytoplankton indicators and the biomass of pelagic fish species.

Read more on the research project sheet.


  • Gittings, J.A., Raitsos, D., Brewin, R.J.W., Hoteit, I. (2021). Links between Phenology of Large Phytoplankton and Fisheries in the Northern and Central Red Sea. Remote Sensing, 13, 231.
  • Gittings, J. A., Brewin, R. J. W., Raitsos, D. E., Kheireddine, M., Ouhssain, M., Jones, B. & Hoteit, I. (2019). Remotely sensing phytoplankton size structure in the Red Sea. Remote Sensing of Environment, 234, 111387.
  • Gittings, J. A., Raitsos, D. E., Kheireddine, M., Racault, M.-F., Claustre, H., & Hoteit, I. (2019). Evaluating tropical phytoplankton phenology metrics using contemporary tools. Scientific Reports, 9(1), 674.
  • Gittings, J. A., Raitsos, D. E., Krokos, G., & Hoteit, I. (2018). Impacts of warming on phytoplankton abundance and phenology in a typical tropical marine ecosystem. Scientific Reports, 8(1), 2240.
  • Gittings, J. A., Raitsos, D. E., Racault, M., Brewin, R. J. W., Pradhan, Y., Sathyendranath, S., & Platt, T. (2017). Remote Sensing of Environment Seasonal phytoplankton blooms in the Gulf of Aden revealed by remote sensing. Remote Sensing of Environment, 189, 56–66.
  • Papagiannopoulos, N., Raitsos, D. E., Krokos, G., Gittings, J. A., Brewin, R. J. W., Papadopoulos, V. P., Pavlidou, A., Selmes, N., Groom, S., & Hoteit, I. (2021). Phytoplankton Biomass and the Hydrodynamic Regime in NEOM, Red Sea. Remote Sensing, 13, 2082.
  • Gokul, E.A., Raitsos, D.E., Gittings, J.A., Hoteit, I. (2020). Developing an atlas of harmful algal blooms in the red sea: Linkages to local aquaculture. Remote Sensing, 12, 1–14.
  • Wang, Y., Raitsos, D.E., Krokos, G., Gittings A., Zhan, P. & Hoteit, I. (2019). Physical connectivity simulations reveal dynamic linkages between coral reef regions in the southern Red Sea and the Indian Ocean. Scientific Reports, 9, 16598.
  • Brewin, B., Morán, X.A.G., Raitsos, D.E., Gittings, J. A., Calleja, M.L., Viegas, M.S., Ansari, M.I., Al-Otaibi, N., Huete-Stauffer, T.M. and Hoteit, I. (2019). Factors regulating the relationship between total and size-fractionated chlorophyll-a in coastal waters of the Red Sea. Frontiers in Microbiology10, 1964.
  • Gokul, E.A., Raitsos, D.E., Gittings, J. A., Alkawri, A., Hoteit, I. (2019). Remotely sensing harmful algal blooms in the Red Sea. PLoS One, 14.
  • Dreano, D., Raitsos, D. E., Gittings, J. A., Krokos, G., & Hoteit, I. (2016). The Gulf of Aden Intermediate Water Intrusion Regulates the Southern Red Sea Summer Phytoplankton Blooms. PLoS ONE, 1–20.


email address
National and Kapodistrian University of Athens, Department of Biology