The Amplifier - v. 1, no. 9

In this issue...Dr. Van Pelt, Lydia's, Old Faithful, Yellowstone National Park, U. S. Gypsum Plant, Stanolind Oil & Gas Company, Coach Olsen, Great Falls Brewery

Rahels Tod : (Nach 1 Mos. 35, 16-20) (Gedicht)

Fürchtegott Christian Fulda

Na 1 Nachlass Max Horkheimer, 23 - Korrespondenzen u.a. mit Gertrud Isch (p. I 12, 1-175)

3 Briefe zwischen R. Imelmann und Max Horkheimer, 20.07.1934, 1934; 2 Briefe vom Institute of International Education New York an Max Horkheimer, 1939-1940; 1 Brief vom Instytut Spraw Spolecznych Warschau an Max Horkheimer, 28.12.1935; 2 Briefe vom International House New York an Max Horkheimer, 1939; 11 Briefe zwischen dem Internationaal Instituut voor Sociale Geschiedenis Amsterdam, 1937-1938; 2 Rundschreiben der International Labour Office Genf, 1940; 2 Briefe von Max Horkheimer an die International Relief Association New York, 1940; 2 Briefe der International Science New York an Max Horkheimer, 1941-1942; 1 Rundbrief und Beilage des International Student Service Genf, 01.03.1934; 3 Briefe und Beilage zwischen Harry Isay und Max Horkheimer, 1941, 13.10.1941; 1 Brief von Max Horkheimer an Elsa Hirschberg, 09.03.1942; 52 Briefe zwischen Gertrude Isch und Max Horkheimer, 1934-1946; 10 Briefe zwischen Karl Israelski und Max Horkheimer, 1937-1938;

Fatty acid and stable isotope composition of calanoid copepods in the open eastern Atlantic Ocean during POLARSTERN cruise ANT-XXIX/1

The majority of global ocean production and total export production is attributed to oligotrophic oceanic regions due to their vast regional expanse. However, energy transfers, food-web structures and trophic relationships in these areas remain largely unknown. Regional and vertical inter- and intra-specific differences in trophic interactions and dietary preferences of calanoid copepods were investigated in four different regions in the open eastern Atlantic Ocean (38°N to 21°S) in October/November 2012 using a combination of fatty acid (FA) and stable isotope (SI) analyses. Mean carnivory indices (CI) based on FA trophic markers generally agreed with trophic positions (TP) derived from d15N analysis. Most copepods were classified as omnivorous (CI ~0.5, TP 1.8 to ~2.5) or carnivorous (CI >=0.7, TP >=2.9). Herbivorous copepods showed typical CIs of <=0.3. Geographical differences in d15N values of epi- (200-0 m) to mesopelagic (1000-200 m) copepods reflected corresponding spatial differences in baseline d15N of particulate organic matter from the upper 100 m. In contrast, species restricted to lower meso- and bathypelagic (2000-1000 m) layers did not show this regional trend. FA compositions were species-specific without distinct intra-specific vertical or spatial variations. Differences were only observed in the southernmost region influenced by the highly productive Benguela Current. Apparently, food availability and dietary composition were widely homogeneous throughout the oligotrophic oceanic regions of the tropical and subtropical Atlantic. Four major species clusters were identified by principal component analysis based on FA compositions. Vertically migrating species clustered with epi- to mesopelagic, non-migrating species, of which only Neocalanus gracilis was moderately enriched in lipids with 16% of dry mass (DM) and stored wax esters (WE) with 37% of total lipid (TL). All other species of this cluster had low lipid contents (< 10% DM) without WE. Of these, the tropical epipelagic Undinula vulgaris showed highest portions of bacterial markers. Rhincalanus cornutus, R. nasutus and Calanoides carinatus formed three separate clusters with species-specific lipid profiles, high lipid contents (>=41% DM), mainly accumulated as WE (>=79% TL). C. carinatus and R. nasutus were primarily herbivorous with almost no bacterial input. Despite deviating feeding strategies, R. nasutus clustered with deep-dwelling, carnivorous species, which had high amounts of lipids (>=37% DM) and WE (>=54% TL). Tropical and subtropical calanoid copepods exhibited a wide variety of life strategies, characterized by specialized feeding. This allows them, together with vertical habitat partitioning, to maintain high abundance and diversity in tropical oligotrophic open oceans, where they play an essential role in the energy flux and carbon cycling.