Phytoplankton size changes and diversity loss in the southwestern Mediterranean Sea in relation to long-term hydrographic variability

Type Article
Date 2020-04
Language English
Author(s) Ramírez-Romero Eduardo1, Molinero Juan-Carlos2, Sommer Ulrich3, Salhi Noussaiba4, Kéfi - Daly Yahia Ons4, 5, Daly Yahia Mohamed Néjib6
Affiliation(s) 1 : Instituto Mediterráneo de Estudios Avanzados, IMEDEA (CSIC-UIB), C/Miquel Marqués 21, 07190, Esporles, Illes Balears, Spain
2 : Institut de Recherche pour le Développement, MARBEC, IRD/CNRS/IFREMER/UM, Sète Cedex, France
3 : GEOMAR Helmholtz Center for Ocean Research, Kiel, Germany, Marine Ecology/Food Webs, Duesternbrooker Weg 20, D-24105, Kiel, Germany
4 : Research Group on Oceanography and Plankton Ecology, Tunisian National Institute of Agronomy (INAT), 43 Avenue Charles Nicolle, 1082, Tunis, Tunisia
5 : IRESA- Carthage University, Tunis El Manar University, LR18ES41, Tunisia
6 : Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, PO Box 2713, Doha, Qatar
Source Estuarine Coastal And Shelf Science (0272-7714) (Elsevier BV), 2020-04 , Vol. 235 , P. 106574 (7p.)
DOI 10.1016/j.ecss.2019.106574
WOS© Times Cited 2
Keyword(s) Size structural changes, Diversity loss, Ocean warming, Nanophytoplankton, Phytoplankton diversity, Southwestern mediterranean
Abstract

Structural changes in plankton primary producers have large implications for food web dynamics, energy fluxes and the vertical export of biogenic particulate carbon. Here we examine phytoplankton data spanning the period 1993–2008 from the Bay of Tunis, southwestern Mediterranean Sea, in relation to long term hydroclimate variability. We show a conspicuous shift in the structure of the phytoplankton community characterized by an increase of small-sized species and diversity loss, revealing a dominance of smaller blooming diatoms and cyanobacteria. Such changes were concurrent with marked modifications in hydroclimatic patterns experienced in the Bay of Tunis consisting of a shift towards enhanced winter precipitation together with rising temperatures. This novel study shows an overall rise in the proportion of small phytoplankton cells and a decreasing trend in phytoplankton diversity in the southern Mediterranean area. These findings warn of a potential decline of trophic efficiency and lesser food web stability resulting from mean size reduction and the diversity loss.

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Ramírez-Romero Eduardo, Molinero Juan-Carlos, Sommer Ulrich, Salhi Noussaiba, Kéfi - Daly Yahia Ons, Daly Yahia Mohamed Néjib (2020). Phytoplankton size changes and diversity loss in the southwestern Mediterranean Sea in relation to long-term hydrographic variability. Estuarine Coastal And Shelf Science, 235, 106574 (7p.). Publisher's official version : https://doi.org/10.1016/j.ecss.2019.106574 , Open Access version : https://archimer.ifremer.fr/doc/00602/71405/