Assessing the Response of Pico- and Nanoplankton to Environmental Pressures in the North-Western Mediterranean Sea

Planktonic microorganisms play a crucial role in marine ecosystems by contributing to nutrient cycles, regulating climate, and supporting the marine food web. However, it is still unclear to what extent they can continue to provide these essential services as they face increasing pressures from climate change and human activities (Abreu et al., 2022). Understanding how environmental and anthropogenic changes affect plankton communities is essential to guide sustainable fisheries management and reduce our impact on ocean health.

Due to their short generation times, marine microorganisms can respond rapidly to environmental changes, making them effective indicators of ecosystem alterations. However, different planktonic organisms may react differently in different regions, under the influence of local environmental factors (Bian et al., 2023). Identifying the dominant drivers of plankton dynamics in specific areas is therefore essential for developing sensitive indicators for ecosystem monitoring.

In our study, we utilize extensive datasets collected by the « SOMLIT » and « COAST-HF » French National Observation Services, which include standardized data on pico- and nanoplankton abundance, optical variables from flow cytometry, and physico-chemical variables since 2012. Most research has mainly focused on microplankton, and medium-term studies on pico- and nanoplankton in the North Western Mediterranean Sea remain limited (Magliozzi et al., 2023). Using advanced statistical techniques such as multivariate analysis, functional data analysis, and time series analysis, we investigate the structure and dynamics of pico- and nanoplankton assemblages at three contrasted coastal sites in the Eastern Mediterranean Sea (Banyuls, Marseille, and Villefranche) that exhibit notable differences in nutrient loads. Our results aim to improve our understanding of how these communities respond to environmental changes and to provide insights into the potential impacts of climate change on marine resources.

References:

Abreu, A., Bourgois, E., Gristwood, A., Troublé, R., Acinas, S. G., Bork, P., Boss, E., Bowler, C., Budinich, M., Chaffron, S., de Vargas, C., Delmont, T. O., Eveillard, D., Guidi, L., Iudicone, D., Kandels, S., Morlon, H., Lombard, F., Pepperkok, R., … Vanaverbeke, J. (2022). Priorities for ocean microbiome research. Nature Microbiology, 7(7), 937–947. https://doi.org/10.1038/s41564-022-01145-5

Bian, V., Cai, M., & Follett, C. L. (2023). Understanding opposing predictions of Prochlorococcus in a changing climate. Nature Communications, 14(1). https://doi.org/10.1038/s41467-023-36928-9

Magliozzi, C., Palma, M., Druon, J. N., Palialexis, A., Abigail, M. G., Ioanna, V., Rafael, G. Q., Elena, G., Birgit, H., Laura, B., & Felipe, A. L. (2023). Status of pelagic habitats within the EU-Marine Strategy Framework Directive: Proposals for improving consistency and representativeness of the assessment. Marine Policy, 148. https://doi.org/10.1016/j.marpol.2022.105467