The Great kNight Folk Club
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The Great kNight Folk Club

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1 The Great kNight Folk Club January to July 2012 Linda Watkins & Mike Moyse p2 Steve Tilston p2 NORTHAMPTONSHIRE'S PREMIER FOLK CLUB We meet 1st & 3rd Tuesday of the month At The Old White Hart Inn, Cotton End, Northampton, NN4 8BS Club Organiser: John New 01604 766154 Floor singers always welcome – contact John if you want a spot For more info go to our Web site: Contact us or join our mailing list at gkfcnorthampton@hotmail.
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Publié par
Nombre de lectures 58
Langue English
Poids de l'ouvrage 1 Mo


Biogeosciences, 8, 3747–3759, 2011 Biogeosciences
doi:10.5194/bg 8 3747 2011
© Author(s) 2011. CC Attribution 3.0 License.
Biogeochemical controls on the bacterial populations in the
eastern Atlantic Ocean
1,2 3,4 5 6 3 1 7,8S. B. Neogi , B. P. Koch , P. Schmitt Kopplin , C. Pohl , G. Kattner , S. Yamasaki , and R. J. Lara
1Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Osaka 599 8531, Japan
2International Centre for Diarrhoeal Disease Research, Bangladesh, 68 Shaheed Tajuddin Ahmed Sarani, Mohakhali,
Dhaka 1212, Bangladesh
3Alfred Wegener Institute for Polar and Marine Research, Ecological Chemistry, Am Handelshafen 12,
27570 Bremerhaven, Germany
4University of Applied Sciences, 27568 Bremerhaven, Germany
5Research Unit BioGeoChemistry and Analytics, Helmholtz Zentrum Munchen,¨ Ingoldstadter¨ Landstr. 1,
85764 Neuherberg, Germany
6Leibniz Institute for Baltic Sea Research, Seestr. 15, 18119 Warnemunde,¨ Germany
7Argentine of Oceanography, 8000 Bah´ıa Blanca, Argentina
8Leibniz Centre for Tropical Marine Ecology GmbH, Fahrenheitstr. 6, 28359 Bremen, Germany
Received: 23 July 2011 – Published in Biogeosciences Discuss.: 4 August 2011
Revised: 29 November 2011 – Accepted: 2 December 2011 – Published: 20 December 2011
Abstract. Little is known about bacterial dynamics in the organic C [POC] and N [PON]). Instead, we found a highly
oligotrophic ocean, particularly about cultivable bacteria. We significant correlation between bacterial abundance and tem
examined the abundance of total and cultivable bacteria in re perature (p< 0.001) and a significant correlation with DOC
lation to changes in biogeochemical conditions in the eastern and DON (p< 0.005 and < 0.01, respectively). In compar-
Atlantic Ocean with special regard to Vibrio spp., a group ison to CBC and DAPI stained prokaryotes, cultivable Vib
of bacteria that can cause diseases in human and aquatic or- rio showed a stronger and highly significant correlation with
ganisms. Surface, deep water and plankton (<20 μm, 20– DOC and DON (p< 0.0005 andp< 0.005, respectively). In
◦55 μm and >55 μm) samples were collected between 50 N cold waters of the mesopelagic and abyssal zones, CBC was
◦ −1and 24 S. Chlorophyll a was very low (<0.3 μg l ) in most 50 to 100 times lower than in the surface layer; however, cul
areas of the nutrient poor Atlantic, except at a few locations tivable Vibrio spp. could be isolated from the bathypelagic
−1near upwelling regions. In surface water, dissolved organic zone and even near the seafloor (average∼10 CFU l ). The
carbon (DOC) and nitrogen (DON) concentrations were 64– depth wise decrease in CBC and Vibrio coincided with the
95 μM C and 2–10 μM N accounting for≥90 % and≥76 % decrease in both DOC and POC. Our study indicates that
of total organic C and N, respectively. DOC and DON grad Vibrio and other bacteria may largely depend on dissolved
ually decreased to ∼45 μM C and <5 μM N in the bottom organic matter to survive in nutrient poor oceanic habitats.
water. In the surface layer, culture independent total bac
0teria and other prokaryotes represented by 4 6 diamidino
72 phenylindole (DAPI) counts, ranged mostly between 10
8 −1 1 Introductionand 10 cells l , while cultivable bacterial counts (CBC)
4 7and Vibrio spp. were found at concentrations of 10 –10
2 5 −1 Oceans play an important role in maintaining the balanceand 10 –10 colony forming units (CFU) l , respectively.
of atmospheric CO . Apart from the conventional biologi 2Most bacteria (>99 %) were found in the nanoplankton frac
cal pump driven vertical transport of surface organic carbontion (<20 μm), however, bacterial abundance did not corre
into the deep sea, the microbial food web remineralizes alate with suspended particulates (chlorophyll a, particulate
large fraction of particulate organic carbon (POC) and ul
timately supports primary production (PP) in the euphotic
Correspondence to: R. J. Lara zone (Azam, 1998). Another part is converted into dissolved
(ruben.lara@zmt organic carbon (DOC) supporting prokaryotic production
Published by Copernicus Publications on behalf of the European Geosciences Union.3748 S. B. Neogi et al.: Biogeochemical controls on the oceanic bacterial populations
(Williams, 2000). The interaction between oceanic bacteria ular analysis have revealed the frequent occurrence of Vib
and their energy sources in the water column is a key issue rio spp. in oceanic water, although other subgroups of bacte
for element fluxes in the ocean. Therefore, detailed infor- ria, e.g., SAR11, Roseobacter, Alteromonas, and Cytophaga
mation is required about variations in bacterial abundance Flavobacterium Bacteroides can also be dominant (Eilers et
caused by changes in oceanic biogeochemistry from the sur- al., 2000; Malmstrom et al., 2005; Weinbauer et al., 2006;
face to abyssopelagic waters. Taniguchi and Hamasaki, 2008; Schattenhofer et al., 2009;
Marine DOC (662 Pg C) is one of the largest active reser- Wietz et al., 2010). However, culture independent tech
voirs of organic C on Earth (Hansell et al., 2009). Bacteria niques cannot provide information on the active, cultivable
have a high growth efficiency when using freshly produced, portion of a species. Cultivable bacteria have a highly active
“labile” DOC which can be degraded within several hours metabolism and are the major functional component within
to days (Reinthaler and Herndl, 2005). The “semi labile” a bacterial population; while the remaining viable but non
DOC (about 15–20 % of net PP) can be degraded by bac cultivable fraction has a reduced metabolism (Roszak and
teria over weeks to seasonal timescales, while “refractory” Colwell, 1987; Sun et al., 2008). Changes in biogeochemical
DOC are resistant to biodegradation and may bear signatures parameters are likely to affect the cultivable fraction more
from centuries to millennia (Hansell et al., 2009). Progres than the non cultivable part of bacterial community.
sive utilization of labile and semi labile DOC through the Although various ecological studies of Vibrio spp. have
microbial carbon pump aids in the accumulation of refractory been performed in coastal habitats (e.g., Heidelberg et al.,
DOC (∼95 % of total DOC) in the oceans interior (Jiao et al., 2002; Mahmud et al., 2007, 2008), little is known about the
2010). In a recent study it has been revealed that such trans regulation of Vibrio or other bacterial communities in the
formation processes in the surface ocean are rapidly leading ocean in response to changes in plankton abundance, tem
to a relatively fresh component which resembles the refrac perature and biogeochemical conditions. Among the oceanic
tory material (Flerus et al., 2011). Besides DOC, the avail bacterial species, Vibrio spp. is of particular interest because
ability and nature of nitrogenous components of dissolved of its link with diseases in humans as well as aquatic or-
organic matter (DOM) play an important role in the bio ganisms. Changes in Vibrio populations in the ocean may
geochemical cycle by limiting bacterial growth. The con ultimately affect their coastal and consequently
centration of dissolved inorganic nitrogen (DIN) in oceanic human health (Constantin de Magny et al., 2008). In the
surface water is often very low and thus phytoplankton and present study, we examined the quantitative abundance of
bacterioplankton are often competing for DIN (Wu et al., total and cultivable bacteria including Vibrio spp. at var-
2000). Therefore, recycling of organic nitrogen from par- ious water depths along a North South meridional transect
ticulate (PON) or dissolved (DON) sources may modulate through the mostly oligotrophic eastern Atlantic Ocean. Our
primary production as well as bacterial abundance. objectives were to elucidate the importance of particulate and
Among the diverse groups of marine and estuarine bac dissolved material for the abundance and distribution of Vib
teria, Vibrio species have gained increased attention due to rio spp. and total cultivable and non cultivable bacteria, and
their potential to cause diseases in humans; such as epi to demonstrate how organic and inorganic substances influ
demic cholera, which is caused by V. cholerae. Some Vibrio ence bacterial populations. A better understanding of the
spp. can also cause diseases in economically important fishes abundance and changes in cultivable and total bacterial com
and shrimps, and have been identified as a cause of coral munities will also improve our knowledge of dynamics and
bleaching and squid luminescence (Thomson et al., 2004). transformation processes of organic carbon and nitrogen in
Vibrio spp. are among the few bacteria that can degrade chiti the ocean.
nous substrates, which are among the most abundant amino
sugars in the ocean (Thompson et al., 2004). Moreover, this
group of bacteria can also secrete a variety of enzymes to aid 2 Materials and methods
the degradation of organic matter, e.g., mucinase, protease,
lipase, and laminarinase (Oliver et al., 1986; Alderkamp et 2.1 Study sites and sampling
al., 2007). As part of their strategy for survival in aquatic
habitats, Vibrio spp. can attach or interact with virtually all Water samples were collected on board R/V Polarstern dur-
kinds of aquatic organisms or suspended particulates (Lara ing the expedition ANT XXV/1 from Bremerhaven, Ger-
et al., 2009,

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