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In the original version of this article (Kunkelova et al. 2018), published on 18 December 2018, there was 1 error in the author name of Dr. Yu. Originally the author name was published as: Siyao Hu The correct name is: Siyao Yu The original publication of this article has been corrected.

Productivity in the Arabian Sea is one of the highest in the world. It is controlled by seasonally reversing monsoonal wind-driven upwelling of nutrient-rich deeper waters which fuel phytoplankton growth. The detailed history of upwelling-induced productivity in the eastern Arabian Sea is unknown. Here we present paleoproductivity records from a composite sediment core at the millennial scale during the last 80 kyr B. P. These records are based on relative abundance counts of planktonic foraminifera and organic carbon contents, which are shown to mainly vary in concert. The eastern Arabian Sea upwelling-induced productivity was higher in the glacial period than in the Holocene, but it fell repeatedly on millennial timescales. These productivity declines occurred during cold events in the North Atlantic region, with the most pronounced changes prevailing during the Heinrich events. Hence, seasonal monsoon winds that drive upwelling-induced productivity in the east were weak when the North Atlantic was cold. These weak winds resulted in stratification of the water column, comparable to today's Arabian Sea stratification in the intermonsoonal period. Combining the new eastern with published western Arabian Sea results shows that the entire biological factory was severely diminished during the North Atlantic Heinrich events, and the seasonal productivity change in the Arabian Sea monsoon system was reduced with year-round low productivity.

Seasonal changes in surface ocean temperature are increasingly recognized as an important parameter of the climate system. Here we assess the potential of analyzing single-specimen planktonic foraminifera as proxy for the seasonal temperature contrast (seasonality). Oxygen isotopes and Mg/Ca ratios were measured on single specimens of Globigerinoides ruber, extracted from surface sediment samples of the Mediterranean Sea and the adjacent Atlantic Ocean. Variability in delta O-18 and Mg/Ca was then compared to established modern seasonal changes in temperature and salinity for both regions. The results show that (1) average delta O-18-derived temperatures correlate with modern annual average temperatures for most sites, (2) the range in delta O-18- and Mg/Ca-derived temperature estimates from single-specimen analysis resembles the range in seasonal temperature values at the sea surface (0-50 m) in the Mediterranean Sea and the Atlantic Ocean, and (3) there is no strong correlation between Mg/Ca- and delta O-18-derived temperatures from the same specimens in the current data set, indicating that other parameters (salinity, carbonate ion concentration, symbiont activity, ontogenesis, and natural variability) potentially affect these proxies.

Berichte aus dem Sonderforschungsbereich 313, Ver��nderungen der Umwelt - Der N��rdliche Nordatlantik