Bacterioplankton viability in Antarctic waters as affected by solar ultraviolet radiation

Ew, Helbling; Er, Marguet; Ve, Villafañe; Holm‐Hansen, Osmund

doi:10.3354/meps126293

Cited by 56 publications

(40 citation statements)

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“…Morán et al (2001) reported that PAR inhibited bacterial activity whereas Sommaruga et al (1997) reported that PAR and UVR have equally inhibitory effects on the rates of both [methyl-3H]-thymidine (TdR) and 14 C-leucine (Leu) utpake in bacteria in the Adriatic Sea. Aas et al (1996) found that PAR in the Gulf of Mexico can actually stimulate bacterial uptake of both tracers, while Helbling et al (1995) reported that PAR radiation has no effect on bacterial growth in the Antarctic waters.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…Phytoplankton and primary production have been the focus of the majority of previous studies (Bidigare 1989, Marchant et al 1991, Holm-Hansen et al 1993, Schick et al 1995, Forster & Lüning 1996, Herrmann et al 1997, Holm-Hansen 1997, Zagarese et al 1997, while significantly less is known about UV radiation effects on bacterioplankton in the Southern Ocean. Helbling et al (1995) reported that viability, based on colony-forming units (CFU), of a natural bacterial assemblage and 2 marine isolates from Antarctic waters decreased significantly when exposed to UV-R. The inhibition of viability due to UV-A was consistently higher than UV-B in all cases, but, interestingly, there were marked differences in the tolerance of the natural assemblage and the 2 isolates to solar radiation, suggesting a heterogeneity in sensitivity among species.…”

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confidence: 99%

“…Undoubtedly, various residents of the marine microbial community have different tolerances and defenses to solar UV radiation (Helbling et al 1995, Joux et al 1999, Arrieta et al 2000. RM11001 must tolerate different periods of UV radiation during the Antarctic spring and summer and as a result of thinning ozone than does the sub-tropical Vibrio natriegens isolate.…”

Section: General Observationsmentioning

confidence: 99%

“…V. natriegens induces RecA and suffers mortality almost equally in response to light containing only UV-A and to light in which UV-A and UV-B are both present. RM11001 is more tolerant of UV-A, suggesting that other mechanisms (perhaps light repair) may be more efficient in repairing UV-A induced lesions in this organism.Undoubtedly, various residents of the marine microbial community have different tolerances and defenses to solar UV radiation (Helbling et al 1995, Joux et al 1999, Arrieta et al 2000. RM11001 must tolerate different periods of UV radiation during the Antarctic spring and summer and as a result of thinning ozone than does the sub-tropical Vibrio natriegens isolate.…”

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confidence: 99%

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Quantification of recA gene expression as an indicator of repair potential in marine bacterioplankton communities of Antarctica

Booth¹,

Hutchinson²,

Brumsted³

et al. 2001

Aquat. Microb. Ecol.

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Marine bacteria in surface waters must cope daily with the damaging effects of exposure to solar radiation (containing both UV-A and UV-B wavelengths), which produces lesions in their DNA. As the stratospheric ozone layer is depleted, these coping mechanisms are likely to play an even more important role in the viability of marine bacterial communities. The recA gene is ubiquitous among eubacteria and is highly conserved both in nucleotide and amino acid sequence. Besides its role in generalized recombination, the gene's translational product, RecA, is the regulator of 'dark repair' activity (DNA-repair mechanisms that do not require visible light as a cofactor). We have taken advantage of this function and used recA gene expression as a barometer of the DNAdamage repair capacity of bacterial assemblages in the Southern Ocean. Studies were conducted in the Gerlache Strait, Antarctica, in the austral springs of 1995 and 1996. Analysis of both recA mRNA and RecA protein extracted from natural communities indicated that the level of expression of this gene varied in a diel fashion, suggesting an increased repair capacity in these organisms. These included an early morning rise in RecA levels followed by a plateau or even a reduction in RecA concentration during the remainder of the day. A much greater increase in RecA was consistently observed after sunset, followed by a constant decrease during the night. Microcosm experiments with a RecA + Gerlache Strait γ-proteobacteria isolate, RM11001, demonstrated a similar diel pattern of expression. These studies demonstrate the usefulness of RecA as a biological indicator of DNA repair capacity in natural bacterial assemblages. They indicate that 'dark repair' of DNA damage is an important coping mechanism for bacteria in the marine environment of Antarctica.KEY WORDS: Southern Ocean · Antarctica · Solar UV radiation · DNA repair · Marine bacterioplankton communities · recA gene · RecA protein Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 24: [51][52][53][54][55][56][57][58][59] 2001 Solar UV radiation consists of UV-C (100 to 280 nm), UV-B (280 to 320 nm), and UV-A (320 to 400 nm) (Peak & Peak 1983). UV-C is environmentally irrelevant because it does not penetrate the earth's atmosphere. UV-B is selectively absorbed by ozone and increases significantly during ozone depletion events (Stolarski 1988). Longer UV-A wavelengths are unaffected by changes in column ozone (Stolarski 1988).Recent evidence suggests that UV-B may have significant effects on marine microbial communities. Phytoplankton and primary production have been the focus of the majority of previous studies (Bidigare 1989, Marchant et al. 1991, Holm-Hansen et al. 1993, Schick et al. 1995, Forster & Lüning 1996, Herrmann et al. 1997, Holm-Hansen 1997, Zagarese et al. 1997, while significantly less is known about UV radiation effects on bacterioplankton in the Southern Ocean. Helbling et al. (1995) reported that viability, based on colony-forming uni...

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“…Santas et al 1998, Helbling et al 2001 and references therein), bacterioplankton (e.g. Helbling et al 1995, Jeffrey et al 1996, Kaiser & Herndl 1997, Gustavson et al 2000, zooplankton (e.g. Chiang et al 2003) and the marine community as whole (e.g.…”

Section: Introductionmentioning

confidence: 99%

Effect of ultraviolet radiation on biofilms and subsequent larval settlement of Hydroides elegans

Hung¹,

Thiyagarajan²,

Wu³

et al. 2005

Mar. Ecol. Prog. Ser.

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This study investigated the effect of UV-A and B (UVR) on larval settlement of the polychaete Hydroides elegans through their influence on biofilms. Multispecies biofilms were treated with 3 doses of UVR (10, ) at 2 environmentally realistic irradiance levels (4 and 2 W m -2 ) in the laboratory, and their ability to induce the settlement of H. elegans larvae was then examined in both laboratory and field conditions. For the field experiment, only 10 and 80 KJ m -2 doses under 4 W m -2 were used. In addition, this study evaluated the effects of UVR on monospecies bacterial biofilms and then their ability to induce larval settlement in the laboratory. Results demonstrated that the ability of multispecies biofilms to trigger larval settlement could be compromised as a result of enhanced UVR exposure. Although larval settlement on multispecies biofilms treated with the lowest UV dose (at both irradiance levels) was at the same level as that of the control, the exposure of biofilms to the highest dose significantly reduced their larval settlement triggering ability. Furthermore, UVR treatments decreased the percentage of metabolically active bacterial cells in monospecies biofilms; the effect increased with increasing UV dose. Larval settlement response to monospecies biofilms decreased with increasing UV dose, suggesting that the bacterial metabolic activity in biofilms is essential for the biofilms to have an inductive effect on larval settlement. This study suggests that enhanced UVR, which might occur due to ozone depletion, may have a significant effect on the larval settlement of H. elegans by affecting a biofilm's inductive cues. KEY WORDS: Hydroides elegans · Larval settlement · Biofilms · Ultraviolet radiation Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 304: [155][156][157][158][159][160][161][162][163][164][165][166] 2005 induce larval settlement. Consequently, biofilms play a key role in determining the recruitment success of invertebrates. The precise interactions among environmental conditions, biofilm dynamics and larval settlement, however, have been poorly investigated (Lau et al. 2005).Among all the potential environmental factors, ultraviolet radiation (UVR, 280 to 400 nm) is considered one of the most important variables in marine ecosystems. Although the ozone layer in the atmosphere filters out most of the biologically destructive UVR, depletion of ozone due to anthropogenic pollution results in an increase in short-wavelength UVR that reaches the earth's surface (Smith et al. 1992). This enhanced UVR causes significant unfavorable effects in marine ecosystems, as both UV-B (280 to 315 nm) and UV-A (315 to 400 nm) can penetrate to significant depths (Kirt 1994, Conde et al. 2000. For example, previous studies documented the negative effects of UVR on phytoplankton (e.g. Santas et al. 1998, Helbling et al. 2001 and references therein), bacterioplankton (e.g. Helbling et al. 1995, Jeffrey et al. 1996, Kaiser & Herndl 1997, Gustavson e...

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Bacterioplankton viability in Antarctic waters as affected by solar ultraviolet radiation

Cited by 56 publications

References 11 publications

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

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

Quantification of recA gene expression as an indicator of repair potential in marine bacterioplankton communities of Antarctica

Effect of ultraviolet radiation on biofilms and subsequent larval settlement of Hydroides elegans

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