The "Be records of four sediment cores forming a transect from the Norwegian Sea at 70"N (core 23059) via the Fram Strait (core 23235) to the Arctic Ocean at 86"N (cores 1533 and 1524) were measured at a high depth resolution. Although the material in all the cores was controlled by different sedimentological regimes, the '('Be records of these cores were superimposed by glacial/interglacial changes in the sedimentary environment. Core sections with high loBe concentrations (> 1. 10' at/g) are related to interglacial stages and core sections with low "Be concentrations (< 0.5. 10' at/g) are related to glacial stages. Climatic transitions (e.g., Termination II, 5/6) are marked by drastic changes in the "Be concentrations of up to one order of magnitude. The average "Be concentrations for each climatic stage show an inverse relationship to their corresponding sedimentation rates, indicating that the "Be records are the result of dilution with more or less terrigenous ice-rafted material. However, there are strong changes in the "Be fluxes (e.g., Termination II) into the sediments which may also account for the observed oscillations. Most likely, both processes affected the "Be records equally, amplifying the contrast between lower (glacials) and higher (interglacials) "Be concentrations. The sharp contrast of high and low "'Be concentrations at climatic stage boundaries are an independent proxy for climatic and sedimentary change in the Nordic Seas and can be applied for stratigraphic dating ("Be stratigraphy) of sediment cores from the northern North Atlantic and the Arctic Ocean.

An artificial surface fihn of oleyl alcohol was produced in the North Sea off Sylt Island to investigate the chemical uniformity of the surface filrn and its influence on gas exchange. Oleyl alcohol concentrations found at the sea surface were in good agreement with previously calculated values. Significant differences between fatty acid concentrations before and after production of the artificial film indicated that the natural surface-active substances were pushed aside by the spreading oleyl alcohol, with small amounts replenished from the underlying water later. The same displacement effect was inferred from the strong reduction in the number of colony-forming units of organotrophic bacteria in the presence of an oleyl alcohol slick. Gas exchange, in this cast dcsorption of CO,, was determined before and after formation of the artificial surface film. In the one experiment performed inhibition of exchange was significant when the film was present: without the film cquilibril~m was achieved after 3.7 Inin, whereas lmder the influence of the film, it took 5.7 min to reach equilibrium.

The reproducibility of tank experiments concerning unicellular marine algal development was analyzed by means of parallel experiments with cultures of Thalassiosira rotula and Skeletonerna costatum, using large flexible plastic tanks under semi-natural condi-

Enclosed ecosystem experiments with marine plankton were carried out in Rosfjord, Nonuay, March-April, 1979. We report results from studies on planktonic bacteria in natural communities and cultures of phytoplankton contained in l -m diameter flexible plastic bags, and compare these to observations in the surrounding sea. Emphasis was on organotrophic bacteria and their diversity dynamics, particularly in relation to phytoplankton. Five previously isolated strains of bacteria were followed by immunofluorescent staining on membrane filters, and the populations of chromobacteria, bdellovibrios and luminescent bacteria were assayed by specific methods. Secondary productivity of total bacterial populations was estimated from growth rate measurements in filtered seawater and compared to net primary production. Possibly, as much as one third of the net production was ultimately consumed by the bacteria. The highly dynamic state of organotrophic bacterial populations and diversity in the sea are demonstrated, and the roles of substrate quality and concentrations and of potential bacterial grazers in population regulation are discussed.