Primary production and bacterial carbon metabolism around South Shetland Islands in the Southern Ocean

Teira, Eva; Mouriño‐Carballido, Beatriz; Martínez‐García, Sandra; Sobrino, Cristina; Ameneiro, Julia; Hernández‐León, Santiago; Vázquez, Elsa

doi:10.1016/j.dsr.2012.07.002

Cited by 25 publications

(16 citation statements)

References 56 publications

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“…Areas around the South Shetland Islands (SSI) are influenced by various water masses during austral winter, including Winter Water (WW), Transitional Bellingshausen Water (TBW), Circumpolar Deep Water (CDW), and Transitional Weddell Water (TWW). These water masses were identified at the sampling stations (5–750 m; Table ; Figure a) according to their temperature and salinity characteristics as described in previous studies [ Sangrà et al ., ; Teira et al ., ]. Cold (−1.9 to −0.5°C) and less saline (33.5–34.3) WW was located in the upper 100 m within the surface mixed layer (Figure b).…”

Section: Resultsmentioning

confidence: 99%

“…However, several studies have suggested a minor effect of temperature on bacterial growth [ Carlson et al ., ; Ducklow and Yager , ; Kirchman et al ., ], and also observed minor grazing on bacteria during phytoplankton blooms [ Anderson and Rivkin , ; Ducklow and Yager , ]. Bacterial production is often found to be significantly correlated with chlorophyll‐ a concentrations and primary production, suggesting a close coupling between bacteria and phytoplankton [ Morán et al ., ; Ortega‐Retuerta et al ., ; Murray et al ., ; Ducklow et al ., ; Teira et al ., ]. Bioassay experiments and field measurements have shown rapid bacterial responses to the supply of bioavailable DOM [ Carlson et al ., ; Obernosterer et al ., ; Ducklow et al ., ].…”

Section: Introductionmentioning

confidence: 99%

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Bioavailable dissolved organic matter and biological hot spots during austral winter in Antarctic waters

et al. 2017

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Primary production and heterotrophic bacterial activity in the Antarctic Ocean are generally low during the austral winter. Organic carbon is considered to be a major factor limiting bacterial metabolism, but few studies have investigated the bioavailability of organic matter during winter. Herein, the chemical composition and bioavailability of dissolved organic matter (DOM) were investigated in surface (5–100 m) and mesopelagic (200–750 m) waters off the northwestern Antarctic Peninsula during August 2012. Concentrations of dissolved organic carbon (DOC) were low (42 ± 4 µmol L−1) and showed no apparent spatial patterns. By contrast, the composition of DOM exhibited significant spatial trends that reflected varying ecosystem productivity and water masses. Surface distributions of chlorophyll‐a and particulate organic carbon depicted a southward decline in primary productivity from open waters (60.0°S–61.5°S) to ice‐covered regions (61.5°S–62.5°S). This trend was evident from concentrations and DOC‐normalized yields of dissolved amino acids in the surface waters, indicating decreasing DOM bioavailability with increasing latitude. A different pattern of DOM bioavailability was observed in the mesopelagic water masses, where amino acids indicated highly altered DOM in the Circumpolar Deep Water and bioavailable DOM in the Transitional Weddell Water. Depth distributions of amino acid yields and compositions revealed hot spots of elevated bioavailable DOM at ∼75 m relative to surrounding waters at most ice‐free stations. Relatively low mole percentages of bacterially derived d‐amino acids in hot spots were consistent with an algal source of bioavailable DOM. Overall, these results reveal the occurrence and spatial heterogeneity of bioavailable substrates in Antarctic waters during winter.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bioavailable dissolved organic matter and biological hot spots during austral winter in Antarctic waters

et al. 2017

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“…On the contrary, if the dispersal rate is low compared with bacterial growth, bacterial assemblages may have time enough for compositional differentiation. Considering a velocity of surface currents in the sampling area of 0.06 ms −1 (corresponds to the main flow in the area, the Brandsfield current, see Sangrà et al ., ) the advection between water mass cores around SSI would last around 2 to 25 days, which is lower than the mean turnover time of bacterioplankton assemblages [ca., 50 days, from data published in Teira et al ., ()], suggesting that the similarity between highly connected water mass pairs may indeed result from physical mixing.…”

Section: Discussionmentioning

confidence: 99%

Water mass mixing shapes bacterial biogeography in a highly hydrodynamic region of the Southern Ocean

Hernando-Morales

Ameneiro

Teira

2016

Environmental Microbiology

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Even though compelling evidences indicate that marine microbes show biogeographic patterns, very little is known on the mechanisms driving those patterns in aquatic ecosystems. In the present study, bacterial community structure was examined in epipelagic waters of a highly hydrodynamic area of the Southern Ocean to gain insight into the role that biogeochemical factors and water mass mixing (a proxy of dispersal) have on microbial biogeography. Four water masses that converge and mix around the South Shetland Islands (northern tip of the Antarctic Peninsula) were investigated. Bacterioplankton communities were water-mass specific, and were best explained by dispersal rather than by biogeochemical factors, which is attributed to the relatively reduced environmental gradients found in these cold and nutrient rich waters. These results support the notion that currents and water mixing may have a considerable effect in connecting and transforming different water bodies, and consequently, in shaping communities of microorganisms. Considering the multidimensional and dynamic nature of the ocean, analysis of water mass mixing is a more suitable approach to investigate the role of dispersal on the biogeography of planktonic microorganisms rather than geographical distance.

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“…The eCFs derived by those authors were very similar to those obtained by Teira et al (31) in the same sampling region using the dilution approach. Summertime Southern Ocean waters are already nutrient rich (29,31), and an increase in nutrient availability through dilution may have little effect on eCFs, supporting the role of trophic status in the effect of the different experimental manipulations for estimating eCFs.…”

Section: Discussionmentioning

confidence: 99%

Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

Teira

Hernando-Morales

Cornejo‐Castillo

et al. 2015

Appl Environ Microbiol

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The transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu ؊1 and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean. P rokaryotic heterotrophic production (PHP), also known as bacterial production, is a key variable for evaluating the role of prokaryotes in ocean carbon fluxes. However, direct PHP measurements by means of biomass increase with time require long incubations (several days). This procedure is excessively timeconsuming for routine measurements at adequate spatial and temporal scales, and therefore, PHP is typically estimated from related metabolic processes. Determining the incorporation rates of radiolabeled substrates, such as leucine and thymidine, is by far the most widespread approach due to the high sensitivity and the short incubation times required (1, 2). However, the transformation of leucine or thymidine incorporation rates into rates of prokaryotic carbon production relies on the use of conversion factors (CFs). In the case of leucine, a theoretical CF of 3.1 kg C mol Leu Ϫ1 was estimated by Simon and Azam (3) based on the protein content of an average bacterial cell and the typical ratio of carbon-toprotein content, assuming a 2-fold dilution with external leucine (or 1.55 kg C mol Leu Ϫ1 assuming no isotope dilution). Regardless of the systematic application of any of these two theoretical CFs in most published studies, compelling evidence indicates that the relation between leucine ...

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Primary production and bacterial carbon metabolism around South Shetland Islands in the Southern Ocean

Cited by 25 publications

References 56 publications

Bioavailable dissolved organic matter and biological hot spots during austral winter in Antarctic waters

Bioavailable dissolved organic matter and biological hot spots during austral winter in Antarctic waters

Water mass mixing shapes bacterial biogeography in a highly hydrodynamic region of the Southern Ocean

Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

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