Biogeochemistry from nine cruises in Northern Adriatic Sea during NA64

The NA64-Mesozooplankton dataset contains biogeochemistry and mesozooplankton data collected in a series of 9 cruises in the Northern Adriatic completed from January 1965 to September 1965 monthly, and December 1965. Biogeochemistry sampling was undertaken using 5L Nansen bottles fired at 0m, 5m, 10m, 20m, 30m and/or bottom depths. The dataset includes 709 samples analysed for nitrate, phosphate, temperature, salinity and density. Mesozooplankton sampling was undertaken at the same locations as for biogeochemistry, using two different net (Hensen non-closing and Appstein closing net). The dataset includes 146 samples analysed for mesozooplankton composition (at higher taxonomic level), abundance and volume settlement. Temperature was measured with a standard oceanographic thermometers. Salinity was determined by titration after Mohr-Knudsen using standardised water I.C.E.S. Copenhagen with 0,01 permil accuracy. Density was calculated using the following equation Sigma-t = T - (sigma 0 + 0,1324) 1 - At + Bt (sigma 0 - 0,1324). Phosphate samples for the determination of nutrients were collected in 500 ml and filtrated through 0,3 µm membrane filter. 3ml of cloroform was added to stabilize the samples. They were analysed after few days in the laboratory on land. Nitrate samples for the determination of nutrients were collected in 500 ml and filtrated through 0,3 µm membrane filter. 3ml of cloroform was added to stabilize the samples. They were analysed after few days in the laboratory on land.

Mg/Ca and d18O measurements of planktonic foraminifera from Sargasso Sea

Paired Mg/Ca and d18O measurements on planktonic foraminiferal species (G. ruber white, G. ruber pink, G. sacculifer, G. conglobatus, G. aequilateralis, O. universa, N. dutertrei, P. obliquiloculata, G. inflata, G. truncatulinoides, G. hirsuta, and G. crassaformis) from a 6-year sediment trap time series in the Sargasso Sea were used to define the sensitivity of foraminiferal Mg/Ca to calcification temperature. Habitat depths and calcification temperatures were estimated from comparison of d18O of foraminifera with equilibrium calcite, based on historical temperature and salinity data. When considered together, Mg/Ca (mmol/mol) of all species, except two, show a significant (r = 0.93) relationship with temperature (T °C) of the form Mg/Ca = 0.38 (±0.02) exp 0.090 (±0.003)T, equivalent to a 9.0 ± 0.3% change in Mg/Ca for a 1°C change in temperature. Small differences exist in calibrations between species and between different size fractions of the same species. O. universa and G. aequilateralis have higher Mg/Ca than other species, and in general, data can be best described with the same temperature sensitivity for all species and pre-exponential constants in the sequence O. universa > G. aequilateralis = G. bulloides > G. ruber = G. sacculifer = other species. This approach gives an accuracy of ±1.2°C in the estimation of calcification temperature. The 9% sensitivity to temperature is similar to published studies from culture and core top calibrations, but differences exist from some literature values of pre-exponential constants. Different cleaning methodologies and artefacts of core top dissolution are probably implicated, and perhaps environmental factors yet understood. Planktonic foraminiferal Mg/Ca temperature estimates can be used for reconstructing surface temperatures and mixed and thermocline temperatures (using G. ruber pink, G. ruber white, G. sacculifer, N. dutertrei, P. obliquiloculata, etc.). The existence of a single Mg thermometry equation is valuable for extinct species, although use of species-specific equations will, where statistically significant, provide more accurate evaluation of Mg/Ca paleotemperature.