Marine phytoplankton response to environmental stressors associated with climate change

• Main Author: Avila Alonso, Dailé
• Other Authors: De Baets, Bernard, Baetens, Jan, Cardenas Ortiz, Rolando
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Ghent University. Faculty of Bioscience Engineering 2022
• Subjects: Earth and Environmental Sciences; Phytoplakton; hurricanes; tropical cyclones; ultraviolet radiation; climate change; North Atlantic
• Online Access: https://biblio.ugent.be/publication/8734017; http://hdl.handle.net/1854/LU-8734017; https://biblio.ugent.be/publication/8734017/file/8734022

The open ocean accounts for nearly 70% of Earth’s surface and represents the largest habitat in the biosphere. Phytoplankton, which are drifting microorganisms with the capacity to perform oxygenic photosynthesis, support life in this vast environment. Besides, they are a key component of marine ecosystems as they drive the oceanic biological pump, influence biogeochemical cycles and modulate fishing yields. However, climate change modifies the environmental drivers governing phytoplankton photosynthesis and consequently alters their productivity, diversity and community structure. Understanding the phytoplankton response to environmental stressors is mandatory to ascertain the implications of current and future climate changes on marine ecosystems in general. Important tools in this respect are remote sensing satellite observations and mathematical models. The former provide high-resolution spatial-temporal observations of key ocean variables, while the latter allow to extrapolate knowledge from the laboratory and sparse field observations to global and regional scales. Hence, the main focus of this thesis is the assessment of the marine phytoplankton response to environmental stressors associated with climate change on the basis of multi-platform datasets, i.e. satellite observations and outputs of mathematical models. More specifically, the response of dominant phytoplanktonic cyanobacteria genera on Earth (Prochlorococcus and Synechococcus) to ultraviolet (UV) radiation is investigated as well as the perturbations induced by hurricanes (strongest tropical cyclones (TCs)) on phytoplankton assemblages in several areas of the western North Atlantic Basin in the period 1998–2019. On the basis of biological weighting function (BWF)/photosynthesis-irradiance (P-E) models, we found that UV accounts for roughly two-thirds of the potential photosynthetic inhibition of Prochlorococcus and Synechococcus in the oceanic photoactive layer in the latitudinal band 40º N/S. Prochlorococcus showed a higher inhibition and ...