Responses of heterotrophic bacteria to solar irradiance in the eastern Pacific Ocean

Pakulski, J. Dean; Baldwin, Amy; Dean, Amanda L.; Durkin, Sarah S.; Karentz, Deneb; Kelley, Cheryl A.; Scott, Kerry; Spero, Howard J.; Wilhelm, Steven W.; Amin, Raid; Jeffrey, Wade H.

doi:10.3354/ame047153

Cited by 21 publications

(22 citation statements)

References 48 publications

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“…However, strong light inhibition was also consistently found in the Adriatic (Sommaruga et al 1997) and the areas of upwelling off the Chilean coast (Hernández et al 2006). Both inhibitory and stimulatory effects were reported by Morán et al (2001) and Pakulski et al (2007), who observed interesting differences between substrates, with overall light Leu stimulation but both stimulation and inhibition of TdR incorporation. Aas et al (1996) also noted light TdR inhibition parallel to Leu stimulation in their samples.…”

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 78%

“…However, incident light, ecosystem trophic status and the composition of bacterial assemblages may help illuminate the elusive question of light vs. dark BP incubations. Thus, higher values of light uptake relative to dark conditions have been found in communities naturally exposed to higher PAR levels along latitudinal (Pakulski et al 2007) or vertical gradients (A. Calvo-Díaz and X. A. G. Morán unpubl.).…”

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

“…A totally different type of explanation considers cyanobacteria (mostly Prochlorococcus) as the organisms responsible for the uptake of labelled substrates in the light (Zubkov et al 2003, Church et al 2004, 2006, Michelou et al 2007). Finally, a relatively stronger negative impact of light on viruses and protistan grazers compared to bacteria (Sommaruga et al 1997, Pakulski et al 2007) and photochemical transformations of extant DOM (Lindell et al 1995, Benner & Biddanda 1998, Obernosterer et al 1999) have also been suggested. Based on the possible mechanisms governing bacterial responses to irradiance listed above, and the likely possibility that 2 or more of these mechanisms can be simultaneously operative, it becomes clear that we are still far from knowing what the relevant controls are.…”

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

“…Spatial differences over large geographical scales have been recently assessed in the works of Pakulski et al (2007) and Michelou et al (2007), but we are not aware of any published seasonal cycle comparing dark and light BP incubations. Preliminary data obtained during 2006 from the southern Bay of Biscay continental shelf (A. Calvo-Díaz and X.…”

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

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Towards a better understanding of microbial carbon flux in the sea*

Gasol¹,

Pinhassi²,

Alonso‐Sáez³

et al. 2008

Aquat. Microb. Ecol.

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We now have a relatively good idea of how bulk microbial processes shape the cycling of organic matter and nutrients in the sea. The advent of the molecular biology era in microbial ecology has resulted in advanced knowledge about the diversity of marine microorganisms, suggesting that we might have reached a high level of understanding of carbon fluxes in the oceans. However, it is becoming increasingly clear that there are large gaps in the understanding of the role of bacteria in regulating carbon fluxes. These gaps may result from methodological as well as conceptual limitations. For example, should bacterial production be measured in the light? Can bacterial production conversion factors be predicted, and how are they affected by loss of tracers through respiration? Is it true that respiration is relatively constant compared to production? How can accurate measures of bacterial growth efficiency be obtained? In this paper, we discuss whether such questions could (or should) be addressed. Ongoing genome analyses are rapidly widening our understanding of possible metabolic pathways and cellular adaptations used by marine bacteria in their quest for resources and struggle for survival (e.g. utilization of light, acquisition of nutrients, predator avoidance, etc.). Further, analyses of the identity of bacteria using molecular markers (e.g. subgroups of Bacteria and Archaea) combined with activity tracers might bring knowledge to a higher level. Since bacterial growth (and thereby consumption of DOC and inorganic nutrients) is likely regulated differently in different bacteria, it will be critical to learn about the life strategies of the key bacterial species to achieve a comprehensive understanding of bacterial regulation of C fluxes. Finally, some processes known to occur in the microbial food web are hardly ever characterized and are not represented in current food web models. We discuss these issues and offer specific comments and advice for future research agendas.

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Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 78%

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

Section: A Specific Example: the Question Of Light Vs Dark Incubatiomentioning

confidence: 99%

See 2 more Smart Citations

Towards a better understanding of microbial carbon flux in the sea*

Gasol¹,

Pinhassi²,

Alonso‐Sáez³

et al. 2008

Aquat. Microb. Ecol.

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“…This effect varies among environments (Pakulski et al 2007). In some cases, visible light can inhibit leucine incorporation, whereas in other systems, it stimulates incorporation rates.…”

Section: Photoheterotrophic Bacteriamentioning

confidence: 99%

Introduction and Overview

Kirchman

2008

Microbial Ecology of the Oceans

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Influence of water mixing on the inhibitory effect of UV radiation on primary and bacterial production in Mediterranean coastal water

et al. 2011

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The scaling of the solar ultraviolet radiation (UVR, 280-400 nm) effect on phyto-and bacterio-plankton at the ecosystem level is difficult since its estimate is often based on short-time incubation experiments performed at fixed depths, neglecting the previous days' radiation history and the variable radiation caused by vertical mixing. To examine this issue, we measured primary (PP) and bacterial (BP) production in samples from coastal water in the Northwest Mediterranean Sea incubated at fixed depths or moving vertically within the water column (0-8 m) with a periodicity of 22 min, exposed to full sun, PAR or maintained in dark. Three experiments were carried out on consecutive days to measure day-to-day variations in planktonic response. In surface waters, PP was inhibited by *32 to 42% by UVR, and BP was inhibited by *50 to 70% by solar radiation (UVR ? PAR). We observed a general decrease in the integrated inhibition of PP due to UVR for both fixed and moving incubations over the 3 days from *27% of inhibition to non-significant inhibition. In contrast, large discrepancies were observed in the integrated inhibition of BP due to solar radiation (UVR ? PAR) between fixed and moving incubations. Whereas both type of incubations gave similar estimation of solar radiation inhibition on day 1 (*25%), inhibition became much higher for fixed incubation compared to moving incubation on days 2 and 3. Differences in responses between days suggest that light history, spectral quality, photoadaptation or acclimation may be important factors in daily observed responses. Our results also underline, for the first time, the importance of the vertical mixing in the BP inhibition by solar radiation.

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Responses of heterotrophic bacteria to solar irradiance in the eastern Pacific Ocean

Abstract: We investigated the effects of sunlight on bacterial 3 H-leucine (Leu) and 3

Cited by 21 publications

References 48 publications

Towards a better understanding of microbial carbon flux in the sea*

Towards a better understanding of microbial carbon flux in the sea*

Introduction and Overview

Influence of water mixing on the inhibitory effect of UV radiation on primary and bacterial production in Mediterranean coastal water

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