Climatically induced changes in late Quaternary bathyal ostracod assemblages of the Camamu Basin, Brazil

Abstract

Bathybic ostracods (i.e., bathyal and abyssal assemblages) are important indicators of temperature and productivity changes of Cenozoic marine ecosystems. The present work presents the first study on Quaternary ostracods of the Camamu Basin, off the state of Bahia, northeastern Brazilian continental margin. The analysis of 59 samples from the piston-core CMU 14 (14°24’S, 38°49’W; 965 m water depth), revealed rich and abundant assemblages. The 14C accelerator mass spectrometry (AMS) dating indicates that the studied interval covers the last 108 kyr, corresponding to the oxygen stable isotope stages (MIS) 5 to 1. Comparison with data from previous publications allowed discernment of three groups of ostracod species in CMU 14: Pandemic Group of species registered in more than one oceanic basin; Atlantic/Mediterranean Group of species restricted to the Atlantic Ocean and Mediterranean; and Brazilian Group of species restricted to the Brazilian continental margin). Four new species are herein proposed: Cytherella pindoramensis sp. nov., Ambocythere amadoi sp. nov., Pseudobosquetina pucketti sp. nov., and Bythoceratina bonaterrae sp. nov. Ostracod occurrences reveal the influence of glacial/interglacial cycles on assemblages composition. Interglacial stages 5 and 1 in the Camamu Basin are characterized by the association Bythocypris affinis–Cytherella pindoramensis sp. nov.– Cytheropteron perlaria–Bradleya dictyon; glacial stages (i.e., 2 to 4) register decreased diversity, possibly due to lower oceanic productivity.