Alpha and beta diversities of late Quaternary bathyal benthonic foraminiferal communities in the NE Caribbean Sea

The 3.85 m-long piston core En20-10, from the NE Caribbean Sea (17 degrees 02.2'N, 63 degrees 03.3'W, 885 m water depth) comprises hemipelagic sediment interrupted by calcareous turbidites at approximately 160-200 cm. SHE Analysis for Biozone Identification (SHEBI) revealed four abundance biozones (ABs), one of which (AB2) was coincident with the turbidites. The AB3/AB4 boundary may be coincident with the Pleistocene/Holocene boundary. The alpha diversities ranged 22.6-36.0 effective species, being lowest in AB2 and highest in the succeeding AB3. The beta diversities were 0.728-1.593. However, only the beta diversity across the AB2/AB3 boundary was significant. This indicates that the major control of alpha diversity was sedimentological, low alpha being associated with the turbidites. The beta diversity across the AB3/AB4 boundary was not significant, which implies that the environmental change at the end of the Pleistocene that impacted the composition of the bathyal fauna did not influence alpha diversity.