ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

The grounding of the Bahia Paraiso: Microbial ecology of the 1989 Antarctic oil spill (1992)

Karl, David M.

Springer

Microbial ecology 24 (1992), S. 77-89

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ISSN: 1432-184X

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract On 28 January 1989 the Bahia Paraiso ran aground and sank near Palmer Station, Antarctica. At least 6.8 × 105 liters of diesel fuel arctic (DFA) were released into semi-enclosed Arthur Harbor and deposited in the nearby intertidal regions. Approximately 6 weeks later, a group of scientists was deployed to evaluate the impact of the oil spill on the surrounding coastal marine ecosystem. Microbial hydrocarbon oxidation potential (14CO2 evolved from 14C-labeled hexadecane) was detected throughout both the oil-impacted and control regions. Hexadecane was mineralized at extremely low rates (0.13–1.21 pmol g−1 sediment dry weight day−1); microbiological turnover time exceeded 2 years. The acute effects of DFA (measured over exposure periods of 3–7 days) on the metabolic activities of sedimentary microorganisms appear to be negligible even at seawater saturation concentrations of DFA. Long-term exposure (120 days) to varying concentrations of DFA resulted in significant decreases (〉90%) in total ATP, but had either no effect or a slight stimulatory effect on metabolic activity and production. In contrast to planktonic microbial communities, increasing incubation temperatures of between 0 and 30°C had a positive effect on rates of metabolism and production of sedimentary assemblages. These results may influence the overall weathering rates of hydrocarbons deposited in the intertidal and supratidal regions of Arthur Harbor and other polar regions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00171972

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2

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A Sea of Change: Biogeochemical Variability in the North Pacific Subtropical Gyre (1999)

Karl, David M.

Springer

Ecosystems 2 (1999), S. 181-214

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ISSN: 1435-0629

Keywords: Key words: oceanography; microbial ecology; nutrients; climate; biodiversity; food webs; microbiology.

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: ABSTRACT The North Pacific Subtropical Gyre (NPSG) is the largest ecosystem on our planet. However, this expansive habitat is also remote, poorly sampled, and therefore not well understood. For example, the most abundant oxygenic phototroph in the NPSG, Prochlorococcus, was described only a decade ago. Other novel Bacteria, Archaea and Eukarya, recently identified by nucleic acid sequence analysis, have not been isolated. In October 1988, an ocean time-series research program was established to study ecosystem processes in the gyre, including rates and pathways of carbon and energy flow, spatial and temporal scales of variability, and coupling of ocean physics to biogeochemical processes. After a decade of ecosystem surveillance, this sentinel observatory has produced an unprecedented data set and some new views of an old ocean. Foremost is evidence for dramatic changes in microbial community structure and in mechanisms of nutrient cycling in response to large-scale ocean–atmosphere interactions. These and other observations demand reassessment of current views of physical-biogeochemical processes in this and other open-ocean ecosystems.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s100219900068

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3

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Nitrogen metabolism by heterotrophic bacterial assemblages in Antarctic coastal waters (1994)

Tupas, Luis M. ; Koike, Isao ; Karl, David M. ; [et al.]

Springer

Polar biology 14 (1994), S. 195-204

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ISSN: 1432-2056

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Field studies to examine the in situ assimilation and production of ammonium (NH4 +) by bacterial assemblages were conducted in the northern Gerlache Strait region of the Antarctic Peninsula. Short term incubations of surface waters containing 15N-NH4 + as a tracer showed the bacterial population taking up 0.041–0.128 μg-atoms Nl−1d−1, which was 8–25% of total NH4 + uptake rates. The large bacterial uptake of NH4 + occurred even at low bacterial abundance during a rich phytoplankton bloom. Estimates of bacterial production using 3H-leucine and -adenine were l.0μgCl−1 d−1 before the bloom and 16.2 μg Cl−1 d−1 at the bloom peak. After converting bacterial carbon production to an estimate of nitrogen demand, NH4 + was found to supply 35–60% of bacterial nitrogen requirements. Bacterial nitrogen demand was also supported by dissolved organic nitrogen, generally in the form of amino acids. It was estimated, however, that 20–50% of the total amino acids taken up were mineralized to NH4 +. Bacterial production of NH4 + was occurring simultaneously to its uptake and contributed 27–55% of total regenerated NH4 + in surface waters. Using a variety of 15N-labelled amino acids it was found that the bacteria metabolized each amino acid differently. With their large mineralization of amino acids and their relatively low sinking rates, bacteria appear to be responsible for a large portion of organic matter recycling in the upper surface waters of the coastal Antarctic ecosystem.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00240524

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4

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Remineralization Ratios in the Subtropical North Pacific Gyre (2000)

Li, Yuan-Hui ; Karl, David M. ; Winn, Christopher D. ; [et al.]

Springer

Aquatic geochemistry 6 (2000), S. 65-85

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ISSN: 1573-1421

Keywords: Mixing model ; preformed nutrients ; Redfield ratios ; Remineralization ratios

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology , Geosciences

Notes: Abstract Based on a new mixing model of two end-members, the water column remineralization ratios of P/N/Corg - O2 = 1/13 ± 1/135 ± 18/170 ± 9 are obtained for the Hawaii Ocean Time-series (HOT) data set at station ALOHA. The traditional Redfield ratios of P/N/Corg/–O2 = 1/16/106/138 have standard deviations of more than 50%, when they are based on the average composition of phytoplankton. Apparently, the remineralization processes in the water column have smoothed out the observed large variability of plankton compositions. A new molar formula for the remineralized plankton may be written as 135H280O105N13P or C25(CH2O)101(CH4)9(NH3)13(H3PO4). Oxidation of this formula results in C25(CH2O)101(CH4)9(NH3)13(H3PO4) + 170O2 → 135CO2 + 132H2O + 13NO3 - + H2PO4 - + 14H+. For comparison, remineralization using Redfield's formula gives: (CH2O)106(NH3)16(H3PO4) + 138O2 → 106CO2 + 122H2O + 16NO3 -+ H2PO4 - + 17H+

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009676300859

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