Description: Particle flux data from 27 sites in the Atlantic Ocean have been compiled in order to determine regional variations in the strength and efficiency of the biological pump and to quantify carbon fluxes over the ocean basin, thus estimating the potential oceanic sequestration of atmospheric CO2. An algorithm is derived relating annual particulate organic carbon (POC) flux to primary production and depth that yields variations in the export ratio (ER = POC flux/primary production) at 125 m of between 0.08 and 0.38 over the range of production from 50 to 400 g C m−2 yr−1. Significant regional differences in changes of the export ratio with depth are related to the temporal stability of flux. Sites with more pulsed export have higher export ratios at 125 m but show more rapid decreases of POC flux with depth, resulting in little geographic variation in fluxes below ∼3000 m. The opposing effects of organic carbon production and calcification on ΔpCO2 of surface seawater are considered to calculate an “effective carbon flux” at the depth of the euphotic zone and at the base of the winter mixed layer. POC flux at the base of the euphotic zone integrated over the Atlantic Ocean between 65°N and 65°S amounts to 3.14 Gt C yr−1. Of this, 5.7% is remineralized above the winter mixed layer and thus does not contribute to CO2 sequestration on climatically relevant timescales. The effective carbon flux, termed Jeff, amounts to 2.47 Gt C yr−1 and is a measure of the potential sequestration of atmospheric CO2 for the area considered. A shift in the composition of sedimenting particles (seen in a decrease of the opal:carbonate ratio) is seen across the entire North Atlantic, indicating a basin-wide phenomenon that may be related to large-scale changes in climatic forcing.

Description: The results of an investigation of tintinnids from the western Arabian Sea are described. A total of 134 closing-net samples was obtained from 22 stations of the German "Meteor" expedition 1964/1965. Distribution charts of the dominant species of tintinnids from the study area are presented as well as a list of the world-wide distribution of these species as derived from the literature. Tintinnids were most abundant in the surface waters. The layer from O-25 m yielded a maximum of 94.3% and a minimum of 61.3% of the tintinnids present from O-175 m; the mean was 80%, There was no significant difference in the vertical distribution between day and night stations nor wasb there any indication of the influence of the thermocline upon vertical distribution of tintinnids. TS-diagrams show different water types in the western Arabian Sea. Temperatur-salinity-tintinniddiagrams indicate regional patterns in the distribution of various species of tintinnids. Some tintinnids can be used as indicator species: Climacorylis scalaria, Parundella lohmanni and Amphorella amphora were typical for the Somali Current whereas Rhabdonella apophysata and Brandtiella palliata indicated the presence of Bast African Coastal Current water. The concentration of tintinnids in the upper 25 m ranged between 4,800 and 39,300 individuals/m3 (mean 19,000/m3). Plasma volume of tintinnids was calculated to permit comparison of different links in the food chain. There was a mean of 51 mm3/m2 in the upper layer, equivalent to a concentration of 2 mm3/m3. Carbon values were computed from the plasma volume of tintinnids, phytoplankton and larger Zooplankton. The ratio of phytoplankton plus microzooplankton carbon to large zooplankton carbon was 1 : 0.8 in the Somali Current, 1 : 0.4 in the Bast African Coastal Current and 1 : 1.2 in the mixing zone of these current systems. Tintinnids are one of the first links in the food chain. It is very likely that a part of the organic detritus and of the nanoplankton is transfered to large herbivores or omnivores via tintinnids and other protozoans. This mechanism might be especially effective during seasons when large phytoplankters are not available in the ocean.