Seasonal flux variability of planktonic foraminifera during 2009–2011 in a sediment trap from Xisha Trough, South China Sea

The flux and seasonality of planktonic foraminifera were studied through a time-series sediment trap deployed in the Xisha Trough, South China Sea from June 2009 to August 2011. The general flux pattern for planktonic foraminifera showed high values during the winter half-year/season (from late September/October to February) and low flux during the rest of the year. This flux pattern contrasts with the bimodal pattern in the central and southern South China Sea, which shows two high flux peaks corresponding to the prevailing summer and winter monsoon periods, respectively. Apparent interannual flux differences, which may be related to the climate change from an El Niño year to a La Niña year, were observed. Monsoonal driven seasonality is most prominent in Pulleniatina obliquiloculata, Neogloboquadrina dutertrei and Globigerina bulloides, with over 80% of their species-specific fluxes (93% for G. bulloides) occurring from late September/October to February. Globigerinoides sacculifer and Globigerinoides ruber show similar seasonality, generally following the trend of the total flux of planktonic foraminifer. G. bulloides may have the potential to be developed as a winter proxy-species. Globigerinoides conglobatus mostly appears in June to August and can be developed as a summer proxy-species.