Papers

A study is presented comparing ERS-1 SAR.FDC images and ADCP ship data in detecting mesoscale structures in the Alboran Sea during September - October, 1992. First results have shown good correlation between the shear lines of such dynamic structures in SAR images and the ship data, especially in the case of the ADCP velocity records. The two big western and eastern anticyclonic gyres, small eddies associated to the first gyre and the formation of an along current in the Algerian coast are identified in both data sets. As occur in many cases using SAR images, the wind conditions played on important role in the detection of such structures.

The respiratory metabolism of the marine bacterium Vibrio natriegens growing in batch cultures with acetate and pyruvate as carbon sources was studied. In particular, the relationship of the activity of the enzyme isocitrate dehydrogenase (IDH) to physiological CO2 production and O-2 consumption was examined. Gas measurements were performed by a new type of respirometer that combined O-2 detection by a Pb-O fuel cell and CO2 detection by infrared absorption. Two different respiratory patterns were observed. On pyruvate, CO2 production and O-2 consumption rates paralleled each other during the exponential and the stationary phases. On acetate, they did not. Growth based on acetate was characterized by a higher O-2 consumption, lower CO2 production, lower respiratory quotient and lower IDH activity than on pyruvate. In both culture media, the in vitro IDH activity remained elevated after the in vivo CO2 production had decreased when the carbon source was exhausted. The range of the respiratory quotient obtained in the acetate cultures suggests that the acetate is partitioned between the Krebs cycle and the glyoxylate bypass in the proportions of 1:4 to 1:2. In the pyruvate cultures, the range of the respiratory quotients indicates that, in the course of the different growth phases, the partitioning of the carbon source between the Krebs cycle and the anaplerotic pathways is variable.

Esta Tesis consta de 4 capítulos. Las áreas de estudio corresponden al Mar catalán y al Mar de Alboran. En el primero se describe el funcionamiento del perfilador acústico por efecto Doppler (ADCP). Las observaciones directas que proporciona de la corriente marina son precisas, frecuentes, de buena resolución vertical en un rango de profundidades que abarca los primeros cientos de metros desde la superficie. El objetivo último del trabajo realizado ha sido convertir el uso de este instrumento, hasta ahora poco utilizado en el Mediterráneo y de forma poco cuantitativa por causas que en la tesis se describen, en una herramienta poderosa en el estudio de la dinámica de mesoescala. En el segundo capítulo se analiza detalladamente los factores que condicionan la calidad de las medidas de la corriente por ADCP, evaluando la imprecisión asociada a las mismas (directamente relacionada con la de la giroscópia del buque y con la del sistema de navegación GPS empleado) y estableciendo un protocolo para su revisión sistemática, como paso previo indispensable para cualquier análisis cuantitativo .