Consumption of dissolved organic carbon by marine bacteria and demand for inorganic nutrients

Abstract

Seawater cultures were used to study seasonal and diel variations in bacterial growth and nutrient availability. In both the Baltic Sea and the Northeast Mediterranean, the least available component for bacterial growth was phosphorus. In the Baltic Sea, carbon was available in excess for bacterial growth on all sampling occasions. Compared to the controls, additions of nonlimiting concentrations of inorganic nitrogen and phosphorus increased the yield of bacteria compared to the control with 156% and the degradation of dissolved organic carbon (DOC) by 64 % (as determined by high temperature catalytic oxidation). Analogous, bacterial growth yield increased along with an accumulation of inorganic nutrients in diel experiments with an intact foodweb (microcosm). The concentration of uthzable carbon (UC) was determined from bacterial consumption of DOC in seawater cultures during non-limiting nutrient conditions. Utilizable phosphorus (UP) and utilizable nitrogen (UN) were calculated by converting the bacterial biomass in the cultures into phosphorus and nitrogen equivalents.In the Baltic the average concentrations of UC, UN and UP were found to be 23 FM C. 0.6 pM N and 0.03 pM P respectively. Heterotrophic bacteria preferentially utilized inorganic nitrogen and phosphorus to support growth on a short time scale (days). Bacterial carbon content decreased as a result of nutrient additions from 51 k 7 to 32 f 5 fg C cell-' Growth efficiencies varied from 11 to 54 % in untreated cultures compared to 14 to 58% in cultures supplemented with nitrogen and phosphorus.

Distinct bacterial-production–DOC–primary-production relationships and implications for biogenic C cycling in the South China Sea shelf

“…Shiah et al (1998) showed that DOC turn-over rate in the western equatorial Pacific could be enhanced two-to ninefold when inorganic nutrients were added. Similar findings were also reported in the Baltic and the Mediterranean seas (Zweifel et al, 1993), the North Atlantic (Kirchman et al, 1991), the Gulf of Mexico (Pomeroy et al, 1995) and even in estuarine ecosystems (Shiah and Ducklow, 1995).…”

Diel periodicity of bacterioplankton in the euphotic zone of the subtropical Atlantic Ocean

“…Thus, despite the expected heterogeneity of the species composition of the bacterioplankton in the subtropical Atlantic (Giovannoni et al 1990, Mullins et al 1995, there is a clear diel pattern in bacterial cell division detectable, indicating phasing of growth. Such diel growth patterns have been reported previously for a number of coastal and open ocean regions and lentic systems , Riemann & Søndergaard 1984, Fuhrman et al 1985, Herndl & Malacic 1987, Zweifel et al 1993, Simon 1994, Gasol et al 1998. Most of these studies used the incorporation of radiolabeled thymidine and/or leucine to determine the diel growth pattern.…”

Pyrosequencing reveals contrasting seasonal dynamics of taxa within Baltic Sea bacterioplankton communities

“…In addition, phosphorus covaried strongly with community composition. It has previously been shown that the availability of phosphorus may limit bacterioplankton growth in the open oceans (for example, see (Cotner et al, 1997)) and in the Northern Baltic Sea (Zweifel et al, 1993), and select for specific bacteria adapted to such nutrient-deprived conditions (Pinhassi and Hagströ m, 2000). Hence, conceivably, the pronounced seasonal oscillations in phosphorus concentration observed at the sampling station, with potentially limiting conditions associated with the Cyanobacterial summer blooms (Table 1), exert a strong selection pressure onto the bacterial community.…”