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Marine and continental palynological evidence for the understanding of modern environments in the Western Mediterranean Sea (Algerian margin and Gulf of Lion)
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Edité par CCSD -
International audience. The Mediterranean Sea is generally described as an oligotrophic area where primary productivity is limited to few coastal environments characterized by nutrient-enriched fluvial inputs. However, several studies have shown that the Western Mediterranean hydrology presents major seasonal productive patterns linked to either large fluviatile inputs (e.g. Adriatic Sea under Po river plumes (Zonneveld et al., 2009) or seasonal upwelling cells (e.g. Alboran sea (Penaud et al., 2011). This study aims at: i) discussing the organic microfossil assemblages (pollen grains, dinoflagellate cysts and other non-pollen palynomorphs) from two different productive zones of the Western Mediterranean Sea as well as ii) underlining the interconnections between marine and continental influence responsible for marine and terrestrial palynomorph present-day spatial distributions. Samples from 25 sites collected from the Gulf of Lion and the Algerian Margin have been analysed in order to compare these two present-day noteworthy productive areas. Results highlight: i) the Gulf of Lion’s marine productivity driven by a conjunction of Rhône river inputs and seasonal upwelling mechanisms, ii) the strong productive pattern of the frontal meeting zone between Modified Atlantic Waters and Surface Mediterranean Waters (i.e. water density front mixings and related upwelling). Moreover, these two productive patterns are discussed at the light of major links allowing to understand continental (vegetation witnesses) and marine (sea-surface hydrological conditions) bio-indicators. This study will therefore allow to better interpret paleoenvironmental signatures derived from palynomorphs in Holocene studies from the Algerian Margin (MD04-2801; (Babonneau et al., 2012) and the Gulf of Lion (KCGC-31; (Bassetti et al., 2016) where palynological investigations have never been performed.
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