Large amounts of Saharan dust and atmospheric particles are annually deposited at the surface Eastern Mediterranean Sea, providing macro-nutrients, micro-trace metals and microbes to this ultra-oligotrophic area and therefore affecting this ecosystem’s function and diversity. The impact of bioaerosols, emitted from rural and urban areas but also those from Saharan dust, on the plankton community structure was examined during a mesocosm experiment using water from the Cretan Sea in May-June 2022. Multiple additions of bioaerosols took place in 6 mesocosms, followed by two additions of Saharan dust collected during an intense deposition event; three more mesocosms served as a control during the 10 days-experiment. Changes induced from these additions, on the autotrophic and heterotrophic surface microbial populations, were studied from viruses to zooplankton. The results suggested that not all autotrophic groups were favored by the available nutrients, introduced via aerosols/dust additions, but only autotrophic flagellates and diatoms. Dinoflagellates and zooplankton were indirectly favored as they preyed on the groups that took advantage of the available nutrients. Saharan dust was found to be a greater trigger of specific plankton and microbial populations compared to bioaerosols. The results of this study are compared to two previous mesocosm experiments (with addition of Saharan dust and mixed-urban aerosols) conducted at the same area.

Primary Presenter: Vivi Pitta, Hellenic Centre for Marine Research (vpitta@hcmr.gr)

Authors:

Paraskevi (Vivi) Pitta, Hellenic Centre for Marine Research, Greece  (vpitta@hcmr.gr)

Iordanis Magiopoulos, Hellenic Centre for Marine Research, Greece  (iordanis@hcmr.gr)

Christos Chantzaras, University of Crete, Greece  (xristosxantzaras@yahoo.gr)

Jose Gonzalez Fernandez, Centro de Investigación Mariña - Universidade de Vigo, Spain  (josegonzalez@uvigo.es)

Kalliopi Violaki, École Polytechnique Fédérale de Lausanne, Switzerland  (kalliopi.violaki@epfl.ch)

Athanasios Nenes, École Polytechnique Fédérale de Lausanne, Switzerland  (athanasios.nenes@epfl.ch)