scholarly journals Light-Stimulated Bacterial Production and Amino Acid Assimilation by Cyanobacteria and Other Microbes in the North Atlantic Ocean

2007 ◽  
Vol 73 (17) ◽  
pp. 5539-5546 ◽  
Author(s):  
Vanessa K. Michelou ◽  
Matthew T. Cottrell ◽  
David L. Kirchman
Keyword(s):  
Amino Acid ◽  
Surface Waters ◽  
Bacterial Production ◽  
North Atlantic Ocean ◽  
Anoxygenic Phototrophic Bacteria ◽  
Leucine Incorporation ◽  
Light Effect ◽  
The North ◽  
20 Nm

ABSTRACT We examined the contribution of photoheterotrophic microbes—those capable of light-mediated assimilation of organic compounds—to bacterial production and amino acid assimilation along a transect from Florida to Iceland from 28 May to 9 July 2005. Bacterial production (leucine incorporation at a 20 nM final concentration) was on average 30% higher in light than in dark-incubated samples, but the effect varied greatly (3% to 60%). To further characterize this light effect, we examined the abundance of potential photoheterotrophs and measured their contribution to bacterial production and amino acid assimilation (0.5 nM addition) using flow cytometry. Prochlorococcus and Synechococcus were abundant in surface waters where light-dependent leucine incorporation was observed, whereas aerobic anoxygenic phototrophic bacteria were abundant but did not correlate with the light effect. The per-cell assimilation rates of Prochlorococcus and Synechococcus were comparable to or higher than those of other prokaryotes, especially in the light. Picoeukaryotes also took up leucine (20 nM) and other amino acids (0.5 nM), but rates normalized to biovolume were much lower than those of prokaryotes. Prochlorococcus was responsible for 80% of light-stimulated bacterial production and amino acid assimilation in surface waters south of the Azores, while Synechococcus accounted for on average 12% of total assimilation. However, nearly 40% of the light-stimulated leucine assimilation was not accounted for by these groups, suggesting that assimilation by other microbes is also affected by light. Our results clarify the contribution of cyanobacteria to photoheterotrophy and highlight the potential role of other photoheterotrophs in biomass production and dissolved-organic-matter assimilation.

scholarly journals Contribution of SAR11 Bacteria to Dissolved Dimethylsulfoniopropionate and Amino Acid Uptake in the North Atlantic Ocean

2004 ◽  
Vol 70 (7) ◽  
pp. 4129-4135 ◽  
Author(s):  
Rex R. Malmstrom ◽  
Ronald P. Kiene ◽  
Matthew T. Cottrell ◽  
David L. Kirchman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Surface Waters ◽  
North Atlantic Ocean ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
The North ◽  
Highly Active

ABSTRACT SAR11 bacteria are abundant in marine environments, often accounting for 35% of total prokaryotes in the surface ocean, but little is known about their involvement in marine biogeochemical cycles. Previous studies reported that SAR11 bacteria are very small and potentially have few ribosomes, indicating that SAR11 bacteria could have low metabolic activities and could play a smaller role in the flux of dissolved organic matter than suggested by their abundance. To determine the ecological activity of SAR11 bacteria, we used a combination of microautoradiography and fluorescence in situ hybridization (Micro-FISH) to measure assimilation of 3H-amino acids and [35S]dimethylsulfoniopropionate (DMSP) by SAR11 bacteria in the coastal North Atlantic Ocean and the Sargasso Sea. We found that SAR11 bacteria were often abundant in surface waters, accounting for 25% of all prokaryotes on average. SAR11 bacteria were typically as large as, if not larger than, other prokaryotes. Additionally, more than half of SAR11 bacteria assimilated dissolved amino acids and DMSP, whereas about 40% of other prokaryotes assimilated these compounds. Due to their high abundance and activity, SAR11 bacteria were responsible for about 50% of amino acid assimilation and 30% of DMSP assimilation in surface waters. The contribution of SAR11 bacteria to amino acid assimilation was greater than would be expected based on their overall abundance, implying that SAR11 bacteria outcompete other prokaryotes for these labile compounds. These data suggest that SAR11 bacteria are highly active and play a significant role in C, N, and S cycling in the ocean.

scholarly journals The circulation of the surface waters of the North Atlantic Ocean

1900 ◽  
Vol 66 (424-433) ◽  
pp. 484-485
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Surface Waters ◽  
North Atlantic Ocean ◽  
The North ◽  
The North Atlantic

In this paper an attempt is made to investigate the normal circulation of the surface waters of the Atlantic Ocean north of 40° N. lat., and its changes, by means of a series of synoptic charts showing the distribution of temperature and salinity over the area for each month of the two years 1896 and 1897.

Similarity in microbial amino acid uptake in surface waters of the North and South Atlantic (sub-)tropical gyres

2011 ◽  
Vol 91 (4) ◽  
pp. 437-446 ◽  
Author(s):  
Polly G. Hill ◽  
Isabelle Mary ◽  
Duncan A. Purdie ◽  
Mikhail V. Zubkov
Keyword(s):  
Amino Acid ◽  
Surface Waters ◽  
Amino Acid Uptake ◽  
South Atlantic ◽  
Acid Uptake ◽  
The North ◽  
North And South

Green Sahara Megaperiods during the Pliocene: What was the role of North Atlantic Ocean temperature?

2020 ◽  
Author(s):  
Paul Wilson ◽  
Amy Jewell ◽  
Anya Crocker ◽  
Solana Buchanan ◽  
Bryce Mitsunaga ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Saharan Dust ◽  
The North ◽  
Sst Variability ◽  
Scan Data ◽  
Sahel Region ◽  
Strong Control

<p>The Sahel region is one of the most vulnerable regions on Earth to anthropogenically-driven climate change, but also one of the least equipped to deal with the consequences. Predictions of precipitation levels over the forthcoming centuries diverge, not only in magnitude, but also in the sign of change. One key aspect of this uncertainty comes from the role of Atlantic Ocean sea surface temperatures (SST), which are known to exert a strong control over precipitation in the Sahel and are implicated in both the major drought of the late 20<sup>th</sup> century and extreme droughts associated with the Heinrich events of the last glacial. To better understand how Sahelian hydroclimate may respond to SST variability in a warmer world, we turn to the Pliocene epoch, when atmospheric CO<sub>2</sub> levels were comparable to present.</p><p> </p><p>We studied sediments from Ocean Drilling Project Site 659, which is situated in the subtropical North Atlantic beneath the major modern summer Saharan dust plume. Our new dust accumulation rates and X-ray fluorescence core scan data indicate that there were major shifts between highly arid conditions and humid intervals with vegetated or “Green Sahara” conditions over much of northern Africa, driven by both solar insolation and glacial-interglacial variability. We also report three unusually long Plio-Pliocene humid intervals (each lasting ca. 100 kyr) characterised by very low dust emissions, that we term “Green Sahara Megaperiods (GSMPs)”. All three of these GSMPs occur at times when insolation variability was weak, resulting in values close to the long-term mean. This observation strongly suggests that factors other than insolation drove the sustained humidity of GSMPs. We present paired alkenone SST estimates and multi-species planktonic foramaniferal isotope records from 3.5–2.3 Myr ago to explore the extent to which the GSMPs were accompanied by intervals of extended warmth in the surface waters of the North Atlantic Ocean.</p>

scholarly journals Papers read to the Society, May 17, 1900.

1900 ◽  
Vol 66 (424-433) ◽  
pp. 375-375
Keyword(s):  
North Atlantic ◽  
Surface Waters ◽  
Atmospheric Pressure ◽  
North Atlantic Ocean ◽  
Comparative Anatomy ◽  
Cerebral Arteries ◽  
Preliminary Note ◽  
The North ◽  
The North Atlantic ◽  
Circulation Of The Blood

I. “The Circulation of the Surface Waters of the North Atlantic Ocean.” By H. N. Dickson. Communicated by Sir John Murray, F. R. S. II. “On Cerebral Anaemia and the Effects which follow Ligation of the Cerebral Arteries.” By Dr. Leonard Hill. Communicated by Dr. Mott, F. R. S. III. “The Influence of Increased Atmospheric Pressure on the Circulation of the Blood. Preliminary Note.” By Dr. Leonard Hill. Communicated by Dr. Mott, F. R. S. IV. “Contributions to the Comparative Anatomy of the Mammalian Eye, chiefly based on Ophthalmoscopic Examination.” By Dr. G. L. Johnson. Communicated by Dr. Gadow, F. R. S.

A 4-year study of avian influenza virus prevalence and subtype diversity in ducks of Newfoundland, Canada

2013 ◽  
Vol 59 (10) ◽  
pp. 701-708 ◽  
Author(s):  
Yanyan Huang ◽  
Michelle Wille ◽  
Ashley Dobbin ◽  
Gregory J. Robertson ◽  
Pierre Ryan ◽  
...  
Keyword(s):  
Influenza Virus ◽  
North America ◽  
Avian Influenza ◽  
Avian Influenza Virus ◽  
North Atlantic Ocean ◽  
Migratory Bird ◽  
The North ◽  
Environmental Reservoir ◽  
American Black

The island of Newfoundland, Canada, is at the eastern edge of North America and has migratory bird connections with the continental mainland as well as across the North Atlantic Ocean. Here, we report a 4-year avian influenza virus (AIV) epidemiological study in ducks in the St. John’s region of Newfoundland. The overall prevalence of AIV detection in ducks during this study was 7.2%, with American Black Ducks contributing the vast majority of the collected samples and the AIV positives. The juvenile ducks showed a significantly higher AIV detection rate (10.6%) compared with adults (3.4%). Seasonally, AIV prevalence rates were higher in the autumn (8.4%), but positives were still detected in the winter (4.6%). Preliminary serology tests showed a high incidence of previous AIV infection (20/38, 52.6%). A total of 43 viruses were characterized for their HA–NA or HA subtypes, which revealed a large diversity of AIV subtypes and little recurrence of subtypes from year to year. Investigation of the movement patterns of ducks in this region showed that it is a largely non-migratory duck population, which may contribute to the observed pattern of high AIV subtype turnover. Phylogenetic analysis of 4 H1N1 and one H5N4 AIVs showed these viruses were highly similar to other low pathogenic AIV sequences from waterfowl in North America and assigned all gene segments into American-avian clades. Notably, the H1N1 viruses, which were identified in consecutive years, possessed homologous genomes. Such detection of homologous AIV genomes across years is rare, but indicates the role of the environmental reservoir in viral perpetuation.

scholarly journals III. The circulation of the surface waters of the north atlantic ocean

1901 ◽  
Vol 196 (274-286) ◽  
pp. 61-203 ◽  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Surface Waters ◽  
Gulf Stream ◽  
North Atlantic Ocean ◽  
Critical Examination ◽  
Northern Latitude ◽  
The North ◽  
History Of ◽  
The North Atlantic

The history of our knowledge of the currents of the North Atlantic Ocean up to the year 1870 has been written once for all by Petermann (I), who in that year published a memoir maintaining, contrary to the opinion of Findlay, Blunt, and Carpenter, that eastern and northern extensions of the Gulf Stream were the prime factors in the circulation. Petermann subjected practically the whole of the material in the way of observations then extant to an exhaustive critical examination, and came to conclusions which are worth quoting, in the summary, inasmuch as the observations of the twenty succeeding years did not seriously modify them :— 1. The hot source and core of the Gulf Stream extends from the Strait of Florida, along the North American coast at all times.... up to the 37th degree of northern latitude.

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