Response of Mallorca shelf ecosystems to an early Holocene humid phase

Benthic foraminiferal data as well as stable oxygen and carbon isotope records of different planktonic and benthic foraminifera from a shelf sediment core off southwest Mallorca document major sedimentological, hydrological and trophic changes during the Holocene. The Holocene relative sea-level rise resulted in the progradation of different sediment facies types characterized by specific benthic foraminiferal assemblages. This succession reflects the evolution from an unstable shelf ecosystem with high-energy conditions at the sea-floor in the earlier Holocene to a more stable shelf ecosystem in the middle and late Holocene. Between approximately 10.3 and 5.5 kyr BP, low δ13C values of the surface dweller Globigerinoides ruber (white) and high difference in δ13C values between the epifaunal Cibicides lobatulus and the infaunal Bulimina aculeata document enhanced input of nutrients in surface waters and high remineralization rates at the sea floor. The trophic change is associated with a change in sediment facies and can be attributed to higher precipitation and consequently, higher nutrient supply via riverine runoff from the island, mainly during the late summer/early fall season. This early Holocene humid interval is nearly contemporaneous to the formation of sapropel S1 in the eastern Mediterranean Sea and the African Humid Period.

► Isotope records and foraminiferal data from the western Mediterranean are presented.
► Benthic shelf ecosystem adaption is related to the Holocene sea-level rise.
► In the early–mid Holocene more humid conditions were established on Mallorca shelf.
► The humid interval is nearly contemporaneous to the sapropel S1 formation.
► Its end is synchronous to the end of the African Humid Period.