Photoinhibition of natural phytoplankton assemblages in Lake Erie exposed to solar ultraviolet radiation

2000 ◽  
Vol 57 (2) ◽  
pp. 371-379 ◽  
Author(s):  
Christopher A Marwood ◽  
Ralph EH Smith ◽  
John A Furgal ◽  
Murray N Charlton ◽  
Keith R Solomon ◽  
...  
Keyword(s):  
Lake Erie ◽  
Pulse Amplitude ◽  
Ultraviolet B ◽  
Surface Radiation ◽  
Low Light ◽  
Solar Ultraviolet Radiation ◽  
Phytoplankton Assemblages ◽  
Photosystem Ii Efficiency ◽  
Kinetics Of ◽  
Modulated Chlorophyll Fluorescence

Photoinhibition was examined in natural assemblages of phytoplankton from Lake Erie exposed to ambient solar radiation. The impacts on photosynthesis of photosynthetically active radiation (400-700 nm) (PAR), ultraviolet-A radiation (320-400 nm) (UVA), and ultraviolet-B radiation (295-320 nm) (UVB) were assessed at three sites on the lake using pulse amplitude modulated chlorophyll fluorescence. Short exposures (<= 30 min) to sunlight containing UVB (1.8-4.4 mmol·m-2) resulted in the rapid loss of up to 60% of photosystem II efficiency (in the dark-adapted state) (Fv/Fm) and quantum yield (in the light-adapted state) (ΔF/F'm). Exposure to UVA (46-105 mmol·m-2) generally diminished Fv/Fm and, to a lesser extent, ΔF/F'm. Short exposures to PAR (733-1588 mmol·m-2) had no significant effects on electron transport. Recovery from UVA- or UVB-induced photoinhibition was complete for Fv/Fm and 90% complete for ΔF/F'm after 2 h in low light. The results indicate that exposures of phytoplankton to surface radiation need only be short in duration to cause substantial UV inhibition of photosynthesis. However, depending on the kinetics of mixing of the water column, recovery of photosynthesis is possible if there is sufficient time for repair of UV damage. Future elevated levels of solar UVB due to ozone depletion could significantly inhibit primary production in mesotrophic lakes such as Lake Erie.

Effects of ultraviolet radiation on rates and size distribution of primary production by Lake Erie phytoplankton

2002 ◽  
Vol 59 (2) ◽  
pp. 317-328 ◽  
Author(s):  
Véronique P Hiriart ◽  
Bruce M Greenberg ◽  
Stephanie J Guildford ◽  
Ralph EH Smith
Keyword(s):  
Ultraviolet Radiation ◽  
Primary Production ◽  
Lake Erie ◽  
Total Production ◽  
Solar Ultraviolet Radiation ◽  
Phytoplankton Primary Production ◽  
Dependent Inhibition ◽  
Rapid Kinetics ◽  
The Impact ◽  
Kinetics Of

The impact of natural solar ultraviolet radiation (UVR), particularly UVB (297–320 nm), on phytoplankton primary production in Lake Erie was investigated during the spring and summer of 1997. Radiocarbon incorporation and size-selective filtration was used to trace total production and its distribution among particulate and dissolved pools. On average, 1-h exposures produced half the UVB-dependent inhibition of total production realized in 8-h exposures, indicating rapid kinetics of photoinhibition. Cumulative UVB-dependent photoinhibition averaged 36% in 8-h simulated surface exposures. The efficiency of photoinhibition was greater for N-deficient than N-replete communities, but was not related to phytoplankton light history, P limitation, or the dominant genera. The proportion of recently fixed carbon occurring in the dissolved pool after 8-h exposures was significantly greater in higher-UVB treatments, whereas the share in picoplankton (<2 µm) was significantly lower. Significant UVB-dependent inhibition of total production was limited on average to relatively severe exposures, but the rapid kinetics of inhibition and the apparent effects on the allocation of carbon suggest it may be important to the lake's food web. Differences in optical properties and thermal stratification patterns suggested that the relatively turbid west basin was potentially more susceptible to UVR photoinhibition than the more transparent east or central basins.

The response of planktonic phosphate uptake and turnover to ultraviolet radiation in Lake Erie

2002 ◽  
Vol 59 (5) ◽  
pp. 778-786 ◽  
Author(s):  
C D Allen ◽  
R E.H Smith
Keyword(s):  
Ultraviolet Radiation ◽  
Lake Erie ◽  
Radiation Treatment ◽  
Phosphate Uptake ◽  
Ultraviolet B ◽  
Phosphate Limitation ◽  
Bacterial Cells ◽  
Near Surface ◽  
Ambient Concentrations ◽  
Uptake Activity

The hypothesis that ambient ultraviolet radiation (UVR), at near-surface intensities, may diminish phosphorus availability to phytoplankton was tested in Lake Erie in July and August of 1998 and 1999. Relative to samples exposed to photosynthetically active radiation (PAR, 400–700 nm) only, those exposed to ultraviolet-B (UVB, 280–320) and (or) ultraviolet-A (UVA, 320–400 nm) in natural sunlight, or kept in darkness, had diminished phosphate uptake rates at elevated (1 µM P) dissolved phosphate concentrations. By contrast, the specific uptake rate of dissolved phosphate at ambient concentrations (turnover rate) was not significantly affected by UVR or darkness. Turnover was usually dominated by particles smaller than 0.8 µm, whereas uptake from elevated concentrations was dominated by larger particles. The size distribution of turnover and uptake activity was not affected by radiation treatment. Chlorophyll a concentrations were decreased by sufficient exposure to UVB and (or) UVA and increased by deprivation of PAR (dark controls), but the concentration of bacterial cells was unaffected. The results showed that UVR inhibited the phosphate uptake potential of larger, probably algal, plankton but did not change the apparent severity of phosphate limitation at ambient concentrations.

scholarly journals Effect of solar ultraviolet radiation (280–400 nm) on the eggs and larvae of Atlantic cod (Gadus morhua)

1999 ◽  
Vol 56 (6) ◽  
pp. 1058-1067 ◽  
Author(s):  
France Béland ◽  
Howard I Browman ◽  
Carolina Alonso Rodriguez ◽  
Jean-François St-Pierre
Keyword(s):  
Water Column ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Outdoor Exposure ◽  
Ultraviolet B ◽  
Solar Ultraviolet Radiation ◽  
Mortality Effect ◽  
Eggs And Larvae ◽  
Very High ◽  
Solar Ultraviolet

In the Gulf of St. Lawrence, Canada, solar ultraviolet B radiation (UV-B, 280-320 nm) penetrates a significant percentage of the summer mixed-layer water column: organisms residing in this layer, such as the eggs of Atlantic cod (Gadus morhua), are exposed to UV-B. In outdoor exposure experiments, Atlantic cod eggs were incubated in the presence versus the absence of UV-B and (or) UV-A (320-400 nm). We tested two hypotheses: H1, UV-B induces mortality in Atlantic cod eggs, and H2, UV-A either exacerbates or mitigates any such UV-B-induced mortality. Hypothesis H1 was supported: there was a significant mortality effect on Atlantic cod eggs exposed to UV-B at the surface and at a depth of 50 cm. Hypothesis H2 was not supported: there was no effect of UV-A. These experiments indicate that Atlantic cod eggs present in the first metre of the water column (likely only a small percentage of the total egg population) are susceptible to UV-B. However, UV-B must be viewed as only one among many environmental factors that produce the very high levels of mortality typically observed in the planktonic early life stages of marine fishes.

Photoinduced Toxicity to Lake Erie Phytoplankton Assemblages from Intact and Photomodified Polycyclic Aromatic Hydrocarbons

2003 ◽  
Vol 29 (4) ◽  
pp. 558-565 ◽  
Author(s):  
Christopher A. Marwood ◽  
Ralph E.H. Smith ◽  
Murray N. Charlton ◽  
Keith R. Solomon ◽  
Bruce M. Greenberg
Keyword(s):  
Polycyclic Aromatic Hydrocarbons ◽  
Aromatic Hydrocarbons ◽  
Lake Erie ◽  
Phytoplankton Assemblages ◽  
Photoinduced Toxicity ◽  
Polycyclic Aromatic

DESORPTION KINETICS OF FLUORANTHENE AND TRIFLURALIN FROM LAKE HURON AND LAKE ERIE, USA, SEDIMENTS

2005 ◽  
Vol 24 (1) ◽  
pp. 31 ◽  
Author(s):  
Marc S. Greenberg ◽  
G. Allen Burton, Jr ◽  
Peter F. Landrum ◽  
Matti T. Leppänen ◽  
Jussi V. K. Kukkonen
Keyword(s):  
Lake Erie ◽  
Lake Huron ◽  
Desorption Kinetics ◽  
Kinetics Of

Solar ultraviolet radiation dependent decrease of particle light absorption and pigments in lake phytoplankton

1997 ◽  
Vol 54 (3) ◽  
pp. 697-704 ◽  
Author(s):  
H Maske ◽  
M Latasa
Keyword(s):  
Light Absorption ◽  
Uv Light ◽  
Spectral Component ◽  
Ultraviolet B ◽  
Cutoff Wavelength ◽  
Solar Ultraviolet Radiation ◽  
Solar Uv ◽  
Band Pass ◽  
Solar Ultraviolet

The ultraviolet (UV) spectral component of daylight on a clear day at mid-latitudes can significantly reduce phytoplankton pigments within a daylight period. Phytoplankton samples from Redberry Lake, Saskatchewan, dominated by cyanobacteria were incubated in quartz bottles under optical long band-pass filters (cutoff wavelength 420-305 nm) in daylight in June. After incubation, samples were filtered, and in vivo particle light absorption (380-700 nm) and pigment concentrations were measured. Solar ultraviolet-B irradiance (UV-B; 280-320 nm) was measured radiometrically. On sunny days the samples that were exposed to daylight UV light showed a relative decrease in particle absorption and pigment concentration after the incubation compared with samples exposed only to visible daylight. No such decrease was observed during an overcast day. The UV-B data did not show a clear relation with the degree of pigment reduction, suggesting that other environmental factors or the state of adaptation partially controlled the pigment decrease of phytoplankton under UV-B exposure. Neither specific spectral components of the absorption spectrum nor specific pigments were more easily degraded than others by solar UV light, although the ratio of zeaxanthin to chlorophyll a probably increased in cyanobacteria as a result of UV exposure.

scholarly journals Stratospheric ozone depletion

2006 ◽  
Vol 361 (1469) ◽  
pp. 769-790 ◽  
Author(s):  
F. Sherwood Rowland
Keyword(s):  
Ultraviolet Radiation ◽  
Ozone Depletion ◽  
Biological Activities ◽  
Stratospheric Ozone ◽  
Ozone Layer ◽  
Ultraviolet B ◽  
Montreal Protocol ◽  
Atmospheric Measurements ◽  
Solar Ultraviolet Radiation ◽  
Solar Ultraviolet

Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO 2 , NO, NO 2 , Cl and ClO. The NO X and ClO X chains involve the emission at Earth's surface of stable molecules in very low concentration (N 2 O, CCl 2 F 2 , CCl 3 F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules.

Post-illumination CO2 Exchange and Light-induced CO2 Bursts during C4 Photosynthesis

1997 ◽  
Vol 24 (4) ◽  
pp. 517 ◽  
Author(s):  
Agu Laisk ◽  
Gerald E. Edwards
Keyword(s):  
Malic Enzyme ◽  
Co2 Exchange ◽  
Co2 Uptake ◽  
Low Light ◽  
Co2 Response ◽  
Amaranthus Cruentus ◽  
Dark Light ◽  
Gas System ◽  
Detailed Kinetics ◽  
Kinetics Of

Detailed kinetics of the post-illumination CO2 exchange, and darklight transients following post-illumination exchange, were measured in leaves of Sorghum bicolor, a NADP-malic enzyme (NADP-ME), and Amaranthus cruentus, a NAD-malic enzyme (NAD-ME) type C4 plant using a gas system that has a full-response time of 3.5 s. The amount of CO2 fixed in the dark (assimilatory charge, AC) was up to 200 µmol m-2 for A. cruentus and 350-450 µmol m-2 for S. bicolor. AC was at its maximum value at CO2 concentrations close to the inflection of the CO2 response curve, and decreased when photosynthesis was limited by low light intensity. The kinetics of post-illumination CO2 fixation indicate that the rate of carboxylation in the C4 cycle is limited by the supply of phosphoenolpyruvate. In A. cruentus, under saturating CO2 the post-illumination CO2 uptake was replaced by a burst (68 µmol m-2). In S. bicolor, the dark-light induction commenced with a rapid CO2 burst (less than 5 s) of 46 µmol m-2, followed by a gulp. The observed CO2 transients show imbalances in the C4 and C3 cycles. In S. bicolor the lack of a post-illumination burst, and the presence of the light- induced CO2 burst is taken as evidence for strict coupling of malate decarboxylation to PGA reduction in NADP-ME species; the opposite response in A. cruentus indicates the lack of strict coupling between the C4 and C3 cycle in NAD-ME species.

Elimination rate constants of 36 PCBs in zebra mussels (Dreissena polymorpha) and exposure dynamics in the Lake St. Clair - Lake Erie corridor

1995 ◽  
Vol 52 (12) ◽  
pp. 2574-2582 ◽  
Author(s):  
Heather Morrison ◽  
Rodica Lazar ◽  
G. Douglas Haffner ◽  
Tamara Yankovich
Keyword(s):  
Steady State ◽  
Rate Constants ◽  
Dreissena Polymorpha ◽  
Lake Erie ◽  
Elimination Rate ◽  
Zebra Mussels ◽  
Elimination Kinetics ◽  
Western Lake ◽  
Order Of Magnitude ◽  
Kinetics Of

The elimination kinetics of 36 PCB congeners, ranging in log octanol–water partition coefficients (log Kow) from 5.60 to 7.50, were determined in zebra mussels (Dreissena polymorpha) with shell lengths from 1.0 to 1.5 cm. Elimination rate constants, based on lipid-normalized data, ranged from 0.172 to 0.042 day−1 and exhibited a significant negative regression with log Kow. Time to 95% steady state ranged from 17.5 to 71.0 days and was used to determine the period over which mussels integrated exposure concentrations. Bioavailable PCB congener concentrations, calculated with a steady-state model, were determined from mussels collected offshore of Middle Sister Island in western Lake Erie. Chemical concentrations in water, estimated using mussels, were within an order of magnitude of direct measurements for congeners with log Kow < 6.6. The rapid elimination kinetics of zebra mussels suggests that these organisms can closely track temporal fluctuations in ambient chemical concentrations, and therefore have the potential to regulate contaminant cycling in aquatic ecosystems.

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