Bacterial abundance, production and ectoproteolytic activity in the Strait of Magellan

Talbot, V.; Giuliano, Laura; Bruni, Vivia; Bianchi, Micheline

doi:10.3354/meps154293

Cited by 30 publications

(5 citation statements)

References 28 publications

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“…In contrast with previous studies (e.g. SOMVILLE & BILLEN 1983, ROSSO & AZAM 1987, TALBOT et al 1997, EAP in our study, demonstrated a weak correlation with bacterial production (p < 0.05, Table 5). In a recent study, SALAT et al (2001) stated that correlations of ectoaminopeptidase activity with bacterial production or abundance are not relevant as regulatory mechanisms and organisms responsible for the expression of the hydrolytic activity cannot be derived directly from in situ observation.…”

Section: Discussioncontrasting

confidence: 99%

“…EAP values measured in this work were close to the values reported by TALBOT et al (1997) from the Strait of Magellan (EAP 4.6 nM h -1 with 200 ÌM leu-MCA added and BP 32 ng C l -1 h -1 ) which were measured at an ambient temperature (8 ± 1 AEC) considerably lower than in our study. They also fell within the range of values obtained from the subtropical and equatorial Pacific with an addition of 1000 ÌM of another analog substrate for aminopeptidase (LLßN, CHRISTIAN & KARL 1995, Table 2).…”

Section: Discussionsupporting

confidence: 89%

“…However, comparison with previous data is particularly difficult considering the unique or narrow range of substrate concentrations usually tested which could mask indications of multiple kinetics as those found in the present study. Multiple kinetics have been reported in eutrophic fjords (HOPPE, 1983), in the Mediterranean Sea (UNANUE et al 1999) as well as in sediments and near-bottom water layers (TALBOT et al 1997, THOLOSAN et al 1999. In a previous laboratory study, we observed that the response of bacterial ectoaminopeptidase activity to the increase of polymers of phytoplanktonic origin was not uniform in different microcosms and depended both on the composition of the planktonic food web and on the way the phytoplanktonic polymers were released (autolysis, copepod or ciliate grazing, CHRISTAKI 1995, CHRISTAKI & VAN WAMBEKE 1995.…”

Section: Discussionmentioning

confidence: 89%

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Heterotrophic bacterial growth and substrate utilization in the oligotrophic Eastern Mediterranean (Aegean Sea)

Christaki¹,

Wambeke

Bianchi

2003

Medit. Mar. Sci.

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Heterotrophic bacterial growth and substrate utilization were studied in March and September of 1997 in the oligotrophic Aegean Sea. Maximum velocities of ectoproteolytic activity (ectoaminopeptidase ctivity, EAP), as well as amino acid assimilation and respiration rates (AA-A, AA-R) were measured along with bacterial production (protein synthesis). At the northern stations which are influenced by the input of the Black Sea waters, rates at 5 m depth of EAP, AA-A and bacterial production were 2 to 3 times higher than at southern stations. Influenced by the Black Sea water, mean bacterial numbers in the 0-100 m layer showed typical oceanic concentrations averaging 0.7 x 10 6 cells ml -1 . These values, along with low bacterial production rates (30 ng C l -1 h -1 ) implied slow growth for bacteria and/or that a large number among them were inactive. Neither bacterial abundance nor production were correlated with primary production. The percentage of amino acids respired was higher in September compared to March, particularly in the northern Aegean (mean 69 %). The enzyme kinetic analysis showed a biphasic model, the transition between the high and low affinity enzymes being obtained at 50 ΜM. Ectoaminopeptidase activity was weakly correlated with bacterial production (p < 0.05), but strongly correlated with respiration rates of amino acids (p < 0.001), suggesting that the substrate used was devoted to maintain energy requirements.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 89%

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Heterotrophic bacterial growth and substrate utilization in the oligotrophic Eastern Mediterranean (Aegean Sea)

Christaki¹,

Wambeke

Bianchi

2003

Medit. Mar. Sci.

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“…We also selected the incubation period for both type of waters considering previous studies in coastaloceanic zone (i.e. Talbot et al 1997, Troncoso et al 2003, Levipan 2006). The incubations were ended by adding cold trichloroacetic acid (TCA 50% w/v).…”

Section: Experimentation During January To February 2004mentioning

confidence: 99%

Effects of solar radiation on bacterioplankton production in the upwelling system off central-southern Chile

Hernández¹,

Quiñones²,

Daneri³

et al. 2006

Mar. Ecol. Prog. Ser.

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The influence of solar radiation on bacterial secondary production (BSP), bacterial growth efficiency (BGE), and growth rates (μ) in upwelling zones of the Humboldt Current System (HCS) is not yet understood. Here we assessed the impact of solar radiation, with special focus on ultraviolet radiation (UVR, 280 to 400 nm) on 2 natural bacterioplankton assemblages with different light history coming from surface waters (0.5 m) and subsurface waters (80 m) off central-southern Chile (36°S). The samples were incubated under ambient irradiance for 4 to 11 h and exposed to 3 spectral radiation treatments: photosynthetically active radiation (PAR, 400 to 700 nm), PAR+UV-A (320 to 700 nm), and PAR+UVR (280, to 700 nm). BSP was estimated by 14 C-leucine (protein synthesis) and [methyl-3 H]-thymidine (DNA synthesis) uptake. Both bacterioplankton assemblages showed significant (p < 0.05) inhibition of BSP, BGE, and μ rates when exposed to PAR radiation; in contrast, responses to UV radiation were more variable. At noon, BSP inhibition was 49 to 53% (PAR), 13 to 30% (UV-A), and 5 to 14% (UV-B) for both assemblages. At sunset, in surface assemblages, protein and DNA synthesis were more limited by UV-A than by UV-B, whereas protein synthesis in the subsurface assemblage was more inhibited by UV-B than by UV-A. The same inhibition patterns were found for BGE and μ, especially with regard to protein synthesis. The daily inhibition of BSP, BGE, and μ in both assemblages was mainly a function of PAR followed by UV-A and UV-B. Our results suggest that solar radiation could play an important role in modulating bacterioplankton dynamics (especially protein synthesis) during active upwelling periods in the HCS.

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“…The whole Magellan Straits system seems to be more similar to mid latitude environments than to an actual periantarctic system. POM concentration and composition appear to be primarily affected by the hydrological conditions (El Sayed and Fryxell, 1993;Von Bodungen et al, 1986;Berdalet et al, 1997;Povero et al, 1998;Talbot et al, 1997). The starting point of organic matter production generally appears to be the stratification of the water masses, induced by seasonal warming and/or local fresh water inputs.…”

Section: Discussionmentioning

confidence: 99%

Particulate organic matter composition in a semi-enclosed Periantarctic system: the Straits of Magellan

Fabiano¹,

Pedrini²,

Danovaro³

et al. 1999

Sci. Mar.

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SUMMARY: The elemental and biochemical composition of particulate organic matter (POM) was investigated in the Straits of Magellan during February-March 1991. Twenty-two stations were selected in order to identify different areas of the Magellan ecosystem from a trophic point of view. The Strait of Magellan can be divided into three subsystems characterized by different hydrological and geomorphological conditions. Seston concentrations were mostly constrained by physical events, particularly the influence of oceanic and land run-off water inputs and the strong vertical mixing and resuspension events. POM composition displayed quali-quantitative differences between the three areas. In the first subsystem, influenced by Pacific waters, the low seston and POM concentrations and the high POC/Chl-a ratio values indicated the general predominance of the detrital and heterotrophic fractions. In the second subsystem, characterized by superficial stratification, higher seston and organic matter concentrations and lower values of POC/Chl-a ratio were found, indicating that this subsystem was influenced by an active autotrophic component. Shallow waters with intense tidal regime and strong vertical mixing characterized the third subsystem, connected to the Atlantic Ocean, which displayed an increasing importance of the inorganic fraction (values of the POC/TSM ratio lower than in the other systems). Moreover, the third subsystem showed higher values of the RNA/DNA ratio, possibly indicating that resuspension events may enhance the metabolic state of the organic particles mainly dominated by heterotrophic components.Key words: Particulate organic matter, biochemical composition, Straits of Magellan . RESUMEN: COMPOSICIÓN DE LA MATERIA ORGÁNICA PARTICULADA EN UN SISTEMA PERIANTÁRTICO SEMI-CERRADO: EL ESTRE-CHO DE MAGALLANES. -Se estudió la composición elemental y bioquímica de la POM (materia orgánica particulada) en el Estrecho de Magallanes durante el periodo febrero-marzo de 1991. Se eligieron 22 estaciones a fin de identificar diferentes áreas del ecosistema magallánico desde un punto de vista trófico. De acuerdo con las características hidrológicas y geomorfológicas dicho Estrecho se puede dividir en 3 subsistemas. Las concentraciones de seston estuvieron condicionadas, principalmente, por los fenómenos físicos y, en particular, por los aportes oceánicos y terrestres, por la mezcla vertical y por los fenómenos de resuspensión. La composición de la materia orgánica particulada (POM) mostró diferencias cualitativas y cuantitativas en las tres áreas. En el primer subsistema, influenciado por las aguas del Océano Pacífico, las bajas concentraciones de seston y POM y los altos valores de la relación POC/clorofila a indicaron una predominancia general de las fracciones detrítica y heterótrofa. En el segundo subsistema, caracterizado por una estratificación superficial, se encontraron altas concentraciones de seston y de materia orgánica y bajos valores de la relación POC/clorofila a, señalando una influencia de la componente...

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Bacterial abundance, production and ectoproteolytic activity in the Strait of Magellan

Cited by 30 publications

References 28 publications

Heterotrophic bacterial growth and substrate utilization in the oligotrophic Eastern Mediterranean (Aegean Sea)

Heterotrophic bacterial growth and substrate utilization in the oligotrophic Eastern Mediterranean (Aegean Sea)

Effects of solar radiation on bacterioplankton production in the upwelling system off central-southern Chile

Particulate organic matter composition in a semi-enclosed Periantarctic system: the Straits of Magellan

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