Water column interleaving: A new physical mechanism determining protist communities and bacterial states

Lovejoy, Connie; Carmack, Eddy C.; Legendre, Louis; Price, Neil M.

doi:10.4319/lo.2002.47.6.1819

Cited by 24 publications

(19 citation statements)

References 48 publications

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“…In contrast, Pacific water, which is the source of the upper mixed layer of the Western Arctic, is high in silicic acid (43,61). Even on small scales, water masses can have an influence on community structure (36,37).…”

Section: Diversitymentioning

confidence: 99%

Diversity and Distribution of Marine Microbial Eukaryotes in the Arctic Ocean and Adjacent Seas

Lovejoy

Massana

Pedrós-Alió

2006

Appl Environ Microbiol

263

235

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We analyzed microbial eukaryote diversity in perennially cold arctic marine waters by using 18S rRNA gene clone libraries. Samples were collected during concurrent oceanographic missions to opposite sides of the Arctic Ocean Basin and encompassed five distinct water masses. Two deep water Arctic Ocean sites and the convergence of the Greenland, Norwegian, and Barents Seas were sampled from 28 August to 2 September 2002. An additional sample was obtained from the Beaufort Sea (Canada) in early October 2002. The ribotypes were diverse, with different communities among sites and between the upper mixed layer and just below the halocline. Eukaryotes from the remote Canada Basin contained new phylotypes belonging to the radiolarian orders Acantharea, Polycystinea, and Taxopodida. A novel group within the photosynthetic stramenopiles was also identified. One sample closest to the interior of the Canada Basin yielded only four major taxa, and all but two of the sequences recovered belonged to the polar diatom Fragilariopsis and a radiolarian. Overall, 42% of the sequences were <98% similar to any sequences in GenBank. Moreover, 15% of these were <95% similar to previously recovered sequences, which is indicative of endemic or undersampled taxa in the North Polar environment. The cold, stable Arctic Ocean is a threatened environment, and climate change could result in significant loss of global microbial biodiversity.The Arctic Ocean (AO) and surrounding seas have traditionally been thought of as being dominated by large phytoplankton of Ͼ20 m (67); however, recent studies show that these waters have active microbial food webs that are often dominated by cells of Ͻ3 m (37, 57) and that cells of Ͻ5 m are responsible for much of the carbon fixation over wide regions of the Arctic Basin (23, 31). The Arctic Ocean is an enclosed sea with a cold, moderately fresh (Ͻ30 practical salinity units) upper mixed layer of 30 to 60 m. These upper photic zone waters are separated from deeper waters by a strong halocline that is maintained by large riverine inputs and the annual formation and melting of sea ice (1). The physical isolation, perennially cold water temperatures (Ͻ0°C), and extreme annual light cycle provide a distinct marine habitat for microorganisms (15). 16S rRNA gene surveys have uncovered novel archaeal and eubacterial sequences from remote polar regions (6,7,12), confirming that these ambient conditions select for particular microorganisms, but there are no equivalent studies of microbial eukaryotes. North polar latitudes are predicted to warm rapidly as a result of global climate change and have already experienced significant impacts (2, 48). An assessment of current microbial diversity is therefore paramount for this region at this early stage in climate modification.Isolated and extreme environments have been important sources of novel phylotypes (33,47) that have contributed to the recent major reassessment of eukaryotic evolution (5). rRNA gene sequences from uncultured marine eukaryotes have also led to major...

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Section: Diversitymentioning

confidence: 99%

Diversity and Distribution of Marine Microbial Eukaryotes in the Arctic Ocean and Adjacent Seas

Lovejoy

Massana

Pedrós-Alió

2006

Appl Environ Microbiol

263

235

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“…It is characterized by opposing currents of cold Arctic Ocean outflow water and warmer Atlantic water meeting over complex bathymetry, with evidence of a dynamic frontal zone showing strong interleaving and mixing features in the center of the region. Biological studies in the North Water have revealed that the surface (0-2 m) distribution of pico-(0.2-2 mm) and nanophytoplankton (2-20 mm) is influenced by distinct surface water masses (Mostajir et al 2001) and that thermohaline intrusions along frontal zones affect the distribution of protists .3 mm (Lovejoy et al 2002). However, the regional distribution of picoeukaryotes throughout the upper water column in the North Water, and the effect of hydrographic features on the distribution and structure of picoeukaryote assemblages, have not been studied.…”

mentioning

confidence: 99%

Water masses and biogeography of picoeukaryote assemblages in a cold hydrographically complex system

Hamilton

Lovejoy

Galand

et al. 2008

Limnology & Oceanography

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We investigated the influence of geographic distance, environmental variables, and water mass origin on picoeukaryote (phytoplankton and other protists ,3 mm) assemblages to assess the presence of biogeographic patterns. The study region was an area of converging Arctic and Atlantic currents where several distinct water masses were overlain and intersecting. Denaturing gradient gel electrophoresis (DGGE) profiles of assemblages revealed 42 distinct band types overall, with minimum richness (8 band types) in Arctic surface water and Atlantic deep water, and maximum richness (22 band types) in regions of water mass mixing. Sequencing of DGGE bands revealed that most sequences (78 of 98) matched uncultured clones from major taxonomic marine groups, including the Acantharea, Bacillariophyceae, Cercozoa, Chrysophyceae, Dinophyceae, Prasinophyceae, Prymnesiophyceae, and stramenopiles, as well as the novel marine stramenopiles (MAST), alveolate groups I and II, and picobiliphytes. Multivariate statistical analysis of DGGE profiles revealed that picoeukaryote assemblage composition was positively correlated with geographic proximity, abiotic environmental conditions (salinity, photosynthetically active radiation, and transmissivity), and biotic community structure (total phototrophic biomass and size class). Picoeukaryote assemblage similarity was also strongly associated with water mass origin; assemblages in close spatial proximity (horizontally or vertically) showed less similarity if located in different water masses, while spatially distant assemblages showed higher similarity if located within the same water mass. This study highlights that ocean hydrodynamics must be considered to fully explain the distribution and diversity of microbes in this fluid realm.

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“…diatoms) generally indicates nutrient input by vertical mixing of the water column, upwelling or eddies (Ryther 1969). Thus, significant differences in plankton composition over short distances are encountered in areas where water masses with different nutritional composition meet (Lovejoy et al 2002). Although this is a well-established concept in phytoplankton ecology, corresponding knowledge of bacterioplankton distribution is largely lacking.…”

Section: Introductionmentioning

confidence: 99%

Spatial variability in bacterioplankton community composition at the Skagerrak-Kattegat Front

Pinhassi¹,

Winding²,

Binnerup³

et al. 2003

Mar. Ecol. Prog. Ser.

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The distribution of bacterial heterotrophic production and cell concentrations in the world oceans is well documented. Nevertheless, information on the distribution of specific bacterial taxa and how this is influenced by environmental factors in separate sea areas is sparse. Here we report on bacterial community structure across the Skagerrak-Kattegat front. The front separates North Sea water from water with a Baltic Sea origin. We documented community differences across the front using denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified bacterial 16S ribosomal DNA and whole-genome DNA hybridization towards community DNA. Analysis of the community 'fingerprints' by DGGE revealed clustering of samples according to side of the front and depth. Consistent with these results, whole-genome DNA hybridization for 28 bacterial species isolated from the sampling region indicated that bacteria related to the Roseobacter clade and Bacteroidetes as well as prosthecate bacteria (e.g. Hyphomonas) showed distinct distribution patterns on each side of the front, and also with depth. Differences in bacterioplankton species composition across the frontal area were paralleled by differences in quantitative variables such as phytoplankton biomass (chl a), dissolved organic carbon, and bacterial production. Furthermore, we observed differences in more descriptive variables such as salinity range, bacterial growth-limiting nutrients and phytoplankton composition. We suggest that not only quantitative but also qualitative differences in variables that affect bacterial growth are required to cause divergence in bacterioplankton community composition between marine regions.

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Water column interleaving: A new physical mechanism determining protist communities and bacterial states

Cited by 24 publications

References 48 publications

Diversity and Distribution of Marine Microbial Eukaryotes in the Arctic Ocean and Adjacent Seas

Diversity and Distribution of Marine Microbial Eukaryotes in the Arctic Ocean and Adjacent Seas

Water masses and biogeography of picoeukaryote assemblages in a cold hydrographically complex system

Spatial variability in bacterioplankton community composition at the Skagerrak-Kattegat Front

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