Benthic foraminifera assemblages and ostracod evidence from Alkyonides Bay continental slope (Gulf of Corinth, NE Mediterranean)

Alkyonides Bay comprises a relative shallow (- 370 m depth) semi- enclosed basin in the eastern Gulf of Corinth that was formed during the Pleistocene. The transition to modern marine conditions is recorded at around 12 ka BP, linked to the Holocene marine transgression, while tectonic activity and sea level changes control the sedimentation in the area throughout the Quaternary. A total of 83 benthic foraminifera and 32 ostracod taxa were recognized in surface and core sediments from the Alkyonides Bay continental slope. Infaunal foraminiferal species of the genera Bulimina, Bolivina, Cassidulina, Hyalinea, Melonis, Eliohedra and Nonionella dominated both surface and Holocene samples, marking a mesotrophic- eutrophic environment. In accordance, the most abundant ostracod species of the autochthonous fauna (Parakrithe spp., Henryhowella sarsii, Cytheropteron spp., Polycope spp., Pterygocythereis jonesi, Buntonia textilis) verify the outer shelf- epibathyal nutrient enriched conditions. Both foraminifera and ostracod data provide additional evidence of down-slope sediment mass- movement linked to the ongoing seismic activity in the area. The semi- enclosed character and the small size of Alkyonides Bay combined with episodic gravity flow deposits, contribute to the continuous enrichment of sediments with high amounts of organic matter. Mesotrophiceutrophic conditions have therefore prevailed since the beginning of the Holocene.