Die kontinuierliche Kultur in der experimentellen Ökologie mariner Mikroorganismen

Die Lebensbedingungen geschlossener Kultursysteme für marine Mikroorganismen weichen von denen des natürlichen Standortes erheblich ab. Die Anwendung der Methode der homokontinuierlichen Kultur ermöglicht es, bei ökologischen Untersuchungen mariner Mikroorganismen den kinetischen Gesetzmäßigkeiten ihres Wachstums in natürlichen offenen Fließsystemen Rechnung zu tragen. Anhand von Beispielen wird die Anwendung der Methode für die Untersuchung reiner und gemischter Populationen diskutiert. In the sea as their natural habitat, micro-organisms can be assumed to live under steady-state conditions for periods of time. On this basis, the continuous culture technique is shown to yield more satisfactory information on microbial ecology than batch culture experiments. The kinetics and applications of open culture systems for pure and mixed populations are discussed and demonstrated

Lake Kivu expedition : geophysics, hydrography, sedimentology (preliminary report)

In March 1971, seven members of the Woods Hole Oceanographic Institution were engaged in a multidisciplinary study of Lake Kivu. This expedition represents part of a long-range program concerned with the structural and hydrographical settings of the East African Rift Lakes and their relationships to the Red Sea and the Gulf of Aden Rifts. The program started in May 1963 with a geophysical study on Lake Malawi (von Herzen and Vacquier, 1967). Several expeditions of our Institution into the Red Sea and Gulf of Aden area in 1964, 1965 and 1966 (Degens and Ross, 1969) provided detailed geological information on the "northern" extension of the East African Rift. And finally our study of last year on Lake Tanganyika c1osed a major gap in the program; it allowed us to out1ine a model on the evolution of a rift which starts with (i) bulging of the earth's crust, (ii) block-faulting, (iii) volcanism and hydrothermal activity, and which has its final stage in (iv) sea floor spreading (Degens et al. 1971). In the case of Lake Tanganyika, only the second stage of this evolution series has been reached, i.e. block-faulting. In contrast, the Red Sea and the Gulf of Aden had already evolved to active sea floor spreading, almost 25 million years ago. Somewhere along the line between Lake Tanganyika and the Gulf of Aden must lie the "missing link" of this evolution series. Lake Kivu, almost 100 miles to the north of Lake Tanganyika is situated at the highest point of the Rift Valley and is surrounded by active volcanoes and geothermal springs. As recently as 1944, lava flows reached the lake shore. This lake was therefore, a natural choice to test our hypothesis on the origin and development of rifts. Furthermore, the occurrence of large quantities of dissolved gases, e.g., CO2 and methane, represented an interesting geochemical phenomenon worthwhile to investigate.Supported by the National Science Foundation with Grants GA 19262, GB 20956, and GU 3927; grants from the Petroleum Research Fund of the American Chemical Society PRF#1943A2; and by private research funds of the Woods Hole Oceanographic Institution