Dinoflagellate cyst distribution in surface sediments of the southern Indian Ocean

We analysed 70 surface sediment samples collected in the southern Indian Ocean in order to document the distribution ses. These organic-walled micro-organisms have a greater potential for preservation than of dinoflagellate cyst assemblages. These organic-walled micro-organisms have a greater potential for preservation than carbonate or silicate microfossils. A total of 53 dinoflagellate cyst taxa were identified, and two new endemic species are described: Selenopemphix antarctica sp. nov. and Impagidinium variaseptum sp. nov. Dominant taxa allowed the recognition of assemblages which show a latitudinal distribution. The circum-Antarctic domain is characterized by assemblages dominated by S. antarctica sp. nov. and accompanied by I. pallidum. The Subantarctic domain is marked by the dominance of Brigantedinium spp. accompanied by Nematosphaeropsis labyrinthus. The Subtropical domain shows high species diversity, taxa dominance varying along onshore to offshore gradient: the neritic assemblage is dominated by Brigantedinium spp., and Spiniferites spp., the outer neritic is characterized by Operculodinium centrocarpum and the oceanic assemblage is dominated by N. labyrinthus. Principal component analysis illustrates that the distribution of dinoflagellate cyst assemblages is controlled by temperature and salinity. Transfer functions based on the best analogues method are developed to reconstruct past sea-surface conditions.