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

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...

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Bibliographic Details
Published in:Estuarine, coastal and shelf science coastal and shelf science, 2020-04, Vol.235, p.106574, Article 106574
Main Authors: Ramírez-Romero, Eduardo, Molinero, Juan Carlos, Sommer, Ulrich, Salhi, Noussaiba, Kéfi - Daly Yahia, Ons, Daly Yahia, Mohamed Néjib
Format: Article
Language:English
Subjects:
Biodiversity and Ecology
Diversity loss
Environmental Sciences
Global Changes
Nanophytoplankton
Ocean warming
Phytoplankton diversity
Size structural changes
Southwestern mediterranean
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Summary: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. •Marked changes were found within phytoplankton in the SW Mediterranean from 1993 to 2008.•Shifts were concurrent with rising winter precipitations and SST.•An increase was found in the relevance of small-sized phytoplankton species.•A diversity loss was captured in the total phytoplankton community and diatoms.•Results warn on potential lesser predictable and stability ecosystem functioning.
ISSN:0272-7714
1096-0015
DOI:10.1016/j.ecss.2019.106574