High penetration of ultraviolet radiation in the south east Pacific waters

Tedetti, Marc; Sempéré, Richard; Vasilkov, A. P.; Charrìère, Bruno; Nérini, David; Miller, William L.; Kawamura, Kimitaka; Raimbault, Patrick

doi:10.1029/2007gl029823

Cited by 76 publications

(79 citation statements)

References 25 publications

(36 reference statements)

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“…UVR penetration is often calculated as the depth of the layer receiving 10% of the light at the surface (Tedetti & Sempéré 2006); this varied from 10 m for UVB (at 305 nm) to 27 m for UVA (at 380 nm), which are important measures when considering that the equivalent 10% layer for PAR corresponded to 34 m. In fact, Tedetti & Sempéré (2006) provided depths of 9 and 16 m receiving the 10% UVBR in the Mediterranean Sea. The transparency in the UVB and UVA bands obtained here for the Mediterranean Sea was equivalent to that reported for other oligotrophic areas, such as the waters around the Marquesas Islands, in the South Pacific (Morel et al 2007, Tedetti et al 2007), but less than that for the clearest oceanic waters, where K d coefficients are half the values reported here (Morel et al 2007, Tedetti et al 2007). Underwater penetration of UVR was transformed in this study to doses received per day, helping to relate the penetration of UV radiation with its potential damage to cyanobacterial populations.…”

Section: Discussionsupporting

confidence: 63%

Synechococcus and Prochlorococcus cell death induced by UV radiation and the penetration of lethal UVR in the Mediterranean Sea

Llabrés

Agustı́²,

Alonso-Laita³

et al. 2010

Mar. Ecol. Prog. Ser.

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Irradiation experiments performed on natural communities of picocyanobacteria from the southwest Mediterranean Sea indicated that natural levels of solar ultraviolet radiation (UVR: 280 to 400 nm) induced important cell death in Prochlorococcus sp., although Synechococcus sp. appeared to be highly resistant. In the treatments where UVB radiation (UVBR, 280 to 315 nm) was excluded, Prochlorococcus also experienced high cell death with short half-life times of 3.01 ± 0.1 SE (h), showing the contribution of UVA radiation (UVAR, 315 to 400 nm) and photosynthetically active radiation (PAR, 400 to 700 nm) to Prochlorococcus cell death. Underwater radiometric measurements conducted during the cruise indicated that penetration of UVR was significant in the Mediterranean waters studied, with minimum diffuse attenuation coefficients of 0.165 and 0.071 m -1 for 313 and 380 nm, respectively. The lethal UV doses required to decrease the picocyanobacteria populations by half, UVLRD 50 , calculated experimentally, were related to underwater UVR penetration in the Mediterranean Sea measured during the cruise. By calculating (from incident irradiances and UVR penetration) the daily UV doses at different depths in the water column, we found that, for sunny days, experimental Prochlorococcus LRD 50 (187 kJ m -2 ) could reach from 10 to 26 m depth. For Synechococcus, however, the depth receiving daily UVLRD 50 (1375 kJ m -2 ) was always shallower, above 5 m depth. The differential sensitivity of the 2 genera and the UV transparency of the Mediterranean Sea suggest that solar radiation could be an important factor influencing the dynamics and distribution of cyanobacterial populations in the surface waters of this oligotrophic sea.

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Section: Discussionsupporting

confidence: 63%

Synechococcus and Prochlorococcus cell death induced by UV radiation and the penetration of lethal UVR in the Mediterranean Sea

Llabrés

Agustı́²,

Alonso-Laita³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…Chlorophyll biomass followed this general trend with very low values in the center of the SPG (0.023 µg l −1 ), with levels reaching 0.3 µg l −1 near the Marquesas Islands and 1 µg l −1 in the Chilean upwelling. The photic layer located at 40-50 m around the Marquesas and upwelling regions deepened in the centre of the SPG, reaching 160 m between 120 • W and 105 • W, which could be expected in the clearest natural waters of the world (Morel et al, 2007;Tedetti et al, 2007). The incident solar radiation was more or less constant during the cruise (41±7 Em −2 s −1 ) with the exception of three very cloudy days (9 to 11 November 2004, e.g.…”

Section: Resultsmentioning

confidence: 99%

“…in the clearest waters of the world's ocean (Morel et al, 2007;Tedetti et al, 2007). Nixon (1995) assigned annual rates of carbon fixation of <100, 100 to 300 and 300 to 500 g C m −2 y −1 in oligotrophic, mesotrophic and eutrophic areas, respectively.…”

Section: Discussionmentioning

confidence: 99%

Evidence for efficient regenerated production and dinitrogen fixation in nitrogen-deficient waters of the South Pacific Ocean: impact on new and export production estimates

2008

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Abstract.One of the major objectives of the BIOSOPE cruise, carried out on the R/V Atalante from OctoberNovember 2004 in the South Pacific Ocean, was to establish productivity rates along a zonal section traversing the oligotrophic South Pacific Gyre (SPG). These results were then compared to measurements obtained from the nutrient -replete waters in the Chilean upwelling and around the Marquesas Islands. A dual 13 C/ 15 N isotope technique was used to estimate the carbon fixation rates, inorganic nitrogen uptake (including dinitrogen fixation), ammonium (NH 4 ) and nitrate (NO 3 ) regeneration and release of dissolved organic nitrogen (DON). The SPG exhibited the lowest primary production rates (0.15 g C m −2 d −1 ), while rates were 7 to 20 times higher around the Marquesas Islands and in the Chilean upwelling, respectively. In the very low productive area of the SPG, most of the primary production was sustained by active regeneration processes that fuelled up to 95% of the biological nitrogen demand. Nitrification was active in the surface layer and often balanced the biological demand for nitrate, especially in the SPG. The percentage of nitrogen released as DON represented a large proportion of the inorganic nitrogen uptake (13-15% in average), reaching 26-41% in the SPG, where DON production played a major role in nitrogen cycling. Dinitrogen fixation was detectable over the whole study area; even in the Chilean upwelling, where rates as high as 3 nmoles l −1 d −1 were measured. In these nutrient-replete waters new production was very high (0.69±0.49 g C m −2 d −1 ) and essentially sustained by nitrate levels. In the SPG, dinitrogen fixation, although occurring at much lower daily rates (≈1-2 nmoles l −1 d −1 ), sustained up to 100% of the new production (0.008±0.007 g C m −2 d −1 ) which was two orders of magnitude lower than that measured in the upwelling. The annual N 2 -fixation of the South PacificCorrespondence to: P. Raimbault (patrick.raimbault@univmed.fr) is estimated to 21×10 12 g, of which 1.34×10 12 g is for the SPG only. Even if our "snapshot" estimates of N 2 -fixation rates were lower than that expected from a recent ocean circulation model, these data confirm that the N-deficiency South Pacific Ocean would provide an ideal ecological niche for the proliferation of N 2 -fixers which are not yet identified.

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“…Given our results, we expect that increased UVB radiation due to depletion of the stratospheric ozone layer (SOL) exerts a larger impact on marine primary producers than on freshwater primary producers. The impact on marine primary producers is likely to have been increased by the fact that the oligotrophic ocean, characterized by deep penetration of high UVB doses (Llabrés and Agustí, 2006;Tedetti et al, 2007) encompasses 70% of the surfaces of world's oceans and, thereby, a large fraction of the biosphere. However, ecosystem buffers may include many other factors (such as species-specific resistance, photo-adaptation capacities, nutrient levels, species habit), which were not assessed here, and these may add to the uncertainty in evaluating the impacts of elevated UVB radiation on marine ecosystems.…”

Section: Discussionmentioning

confidence: 99%

“…Because UVB was believed to be absorbed rapidly in aquatic ecosystems, the impacts of UVB radiation were believed to be stronger on terrestrial photosynthetic organisms than on marine photosynthetic organisms (Rozema et al, 2002). However, UVB penetrates to considerable depths in freshwater and marine ecosystems (Llabrés and Agustí, 2006;Tedetti et al, 2007), thereby impacting marine photosynthetic organisms as well, although the penetration of UVB varies with latitude, season and water turbidity (Hanelt et al, 2001;Wiencke et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Contrasting Responses of Marine and Freshwater Photosynthetic Organisms to UVB Radiation: A Meta-Analysis

2017

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Ultraviolet-B (UVB) radiation is a global stressor that has profound impacts on freshwater and marine ecosystems. However, an analysis of the patterns of sensitivity to UVB radiation across aquatic photosynthetic organisms has not yet been published. Here, we performed a meta-analysis on results reported in 214 studies compiled from the published literature to quantify and compare the magnitude of responses of aquatic photosynthetic organisms to changes in UVB radiation. The meta-analysis was conducted on observations of marine (n = 893) and freshwater macroalgae (n = 126) and of marine (n = 1,087) and freshwater (n = 2,889) microalgae (total n = 4,995). Most of these studies (85%) analyzed the performance of organisms exposed to natural solar radiation when UVB was partially or totally reduced compared with the organismal performance under the full solar radiation spectrum, whereas the remaining 15% of the studies examined the responses of organisms to elevated UVB radiation mostly using artificial lamps. We found that marine photosynthetic organisms tend to be more sensitive than freshwater photosynthetic organisms to UVB radiation; responses to either decreased or increased UVB radiation vary among taxa; the mortality rate is the most sensitive of the trait responses to elevated UVB radiation, followed by changes in cellular and molecular traits; the sensitivity of microalgae to UVB radiation is dependent on size, with small-celled microalgae more sensitive than large-celled microalgae to UVB radiation. Thick macroalgae morphotypes were the less sensitive to UVB, but this effect could not be separated from phylogenetic differences. The high sensitivity of marine species, particularly the smallest photosynthetic organisms, to increased UVB radiation suggests that the oligotrophic ocean, a habitat comprising 70% of the world's oceans with high UVB penetration and dominated by picoautotrophs, is extremely vulnerable to changes in UVB radiation.

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High penetration of ultraviolet radiation in the south east Pacific waters

Cited by 76 publications

References 25 publications

Synechococcus and Prochlorococcus cell death induced by UV radiation and the penetration of lethal UVR in the Mediterranean Sea

Synechococcus and Prochlorococcus cell death induced by UV radiation and the penetration of lethal UVR in the Mediterranean Sea

Evidence for efficient regenerated production and dinitrogen fixation in nitrogen-deficient waters of the South Pacific Ocean: impact on new and export production estimates

Contrasting Responses of Marine and Freshwater Photosynthetic Organisms to UVB Radiation: A Meta-Analysis

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