In the following study respiratory metabolism of two different physiological states in distinct nutrient type grown cultures of two marine bacteria were compared because of the key role respiration plays in ocean processes. Respiration (R) throughout the ocean is ubiquitous; it consumes organic carbon and produces CO2. For the oxic parts of the world ocean, where R also consumes oxygen during aerobic respiration, we focus on the relationship between CO2 production and the concurrent utilization of O2 For the last 500 million years R has balanced oxygenic photosynthesis (P) on the planet (Lyons et al., 2014) and , likely in the marine carbon cycle also. However, until the Winkler O2 technique was modified (Bryan et al. 1976) R was not well researched because it was so difficult to measure. With this improved technology, oceanographers began to note an excess of R over P in some parts of the ocean, giving rise to the current controversy about the metabolic balance of the ocean (Ducklow & Doney 2013). The quandary is whether the oligotrophic ocean is autotrophic or heterotrophic. Williams et al. (2012) reported in situ observations where the results using natural seawater isotope composition clearly showed an autotrophic state whereby results from modified Winkler analysis on incubated seawater samples (Duarte et al., 2013) showed a heterotrophic one. One reason for this discrepancy could be the assumed value for the respiration quotient (RQ), a key variable of our study and in their calculations. It is used to convert R in oxygen units from the Winkler analysis into respiratory CO2 production (RCO2) in carbon units. Without this conversion respiratory O2 consumption measurements cannot be compared to photosynthetic carbon production or to plankton primary productivity. Consequently, a deep understanding and careful measurement of RQ is essential for progress in resolving, not only this oceanographic quandary, but also for making many other marine ecosystems calculations, including carbon flux (Packard & Christensen 2004, Steinberg et al. 2008, Packard & Gomez 2013). [...]

V Congress of Marine Sciences, 11-13 June 2014, Las Palmas de Gran Canaria.-- 2 pages

Peer Reviewed