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Title: Impact of ultraviolet-B radiation on photosystem II activity and its relationship to the inhibition of carbon fixation rates for antarctic ice algae communities

Abstract

One goal of the Icecolors 1993 study was to determine whether or not photosystem II (PSII) was a major target site for photoinhibition by ultraviolet-B radiation (Q{sub UVB}, 280-320 nm) in natural communities. Second, the degree to which Q{sub UVB} inhibition of PSII could account for Q{sub UVB} effects on whole cell rates of carbon fixation in phytoplankton was assessed. On 1 October, 1993, at Palmer Station (Antarctica), dense samples of a frazil ice algal community were collected and maintained outdoors in the presence or absence of Q{sub UVB} and/or ultraviolet-A (Q{sub UVA}, 320-400 nm) radiation. The time of day course of UV inhibition of primary production was tracted. Over the day, {phi}{sub IIe}{degrees} declined due to increasing time-integrated dose exposure of Q{sub UVB}. The Q{sub UVB}-driven inhibition of {phi}{sub IIe}{degrees} increased from 4% in the early morning hours to a maximum of 23% at the end of the day. The Q{sub UVB} photoinhibition of PSII quantum yield did not recover by 6 h after sunset. In contrast, photoinhibition by Q{sub UVA} and photosynthetically available radiation (Q{sub PAR}, 400-700 nm) recovered during the late afternoon. Fluorescence-based estimates of carbon fixation rates were linearly correlated with measured carbon fixation. Fluorescence overestimatedmore » the observed Q{sub UVB} inhibition in measured carbon fixation rates. Researchers should be cautious in using fluorescence measurements to infer ultraviolet inhibition for rates of carbon fixation until there is a greater understanding of the coupling of carbon metabolism to PSII activity for natural populations. Despite these current limitations, fluorescence-based technologies represent powerful tools for studying the impact of the ozone hole on natural populations on spatial/temporal scales not possible using conventional productivity techniques. 55 refs., 11 figs., 2 tabs.« less

Authors:
;  [1];  [2]
  1. Univ. of California, Santa Barbara, CA (United States)
  2. Univ. of Amsterdam (Netherlands)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
181884
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Phycology; Journal Volume: 31; Journal Issue: 5; Other Information: PBD: Oct 1995
Country of Publication:
United States
Language:
English
Subject:
56 BIOLOGY AND MEDICINE, APPLIED STUDIES; PHOTOSYNTHESIS; BIOLOGICAL RADIATION EFFECTS; ALGAE; PRODUCTIVITY; OZONE LAYER; ENVIRONMENTAL EFFECTS; ANTARCTICA; ULTRAVIOLET RADIATION

Citation Formats

Schofield, O., Prezelin, B.B., and Kroon, B.M.A. Impact of ultraviolet-B radiation on photosystem II activity and its relationship to the inhibition of carbon fixation rates for antarctic ice algae communities. United States: N. p., 1995. Web. doi:10.1111/j.0022-3646.1995.00703.x.
Schofield, O., Prezelin, B.B., & Kroon, B.M.A. Impact of ultraviolet-B radiation on photosystem II activity and its relationship to the inhibition of carbon fixation rates for antarctic ice algae communities. United States. doi:10.1111/j.0022-3646.1995.00703.x.
Schofield, O., Prezelin, B.B., and Kroon, B.M.A. 1995. "Impact of ultraviolet-B radiation on photosystem II activity and its relationship to the inhibition of carbon fixation rates for antarctic ice algae communities". United States. doi:10.1111/j.0022-3646.1995.00703.x.
@article{osti_181884,
title = {Impact of ultraviolet-B radiation on photosystem II activity and its relationship to the inhibition of carbon fixation rates for antarctic ice algae communities},
author = {Schofield, O. and Prezelin, B.B. and Kroon, B.M.A.},
abstractNote = {One goal of the Icecolors 1993 study was to determine whether or not photosystem II (PSII) was a major target site for photoinhibition by ultraviolet-B radiation (Q{sub UVB}, 280-320 nm) in natural communities. Second, the degree to which Q{sub UVB} inhibition of PSII could account for Q{sub UVB} effects on whole cell rates of carbon fixation in phytoplankton was assessed. On 1 October, 1993, at Palmer Station (Antarctica), dense samples of a frazil ice algal community were collected and maintained outdoors in the presence or absence of Q{sub UVB} and/or ultraviolet-A (Q{sub UVA}, 320-400 nm) radiation. The time of day course of UV inhibition of primary production was tracted. Over the day, {phi}{sub IIe}{degrees} declined due to increasing time-integrated dose exposure of Q{sub UVB}. The Q{sub UVB}-driven inhibition of {phi}{sub IIe}{degrees} increased from 4% in the early morning hours to a maximum of 23% at the end of the day. The Q{sub UVB} photoinhibition of PSII quantum yield did not recover by 6 h after sunset. In contrast, photoinhibition by Q{sub UVA} and photosynthetically available radiation (Q{sub PAR}, 400-700 nm) recovered during the late afternoon. Fluorescence-based estimates of carbon fixation rates were linearly correlated with measured carbon fixation. Fluorescence overestimated the observed Q{sub UVB} inhibition in measured carbon fixation rates. Researchers should be cautious in using fluorescence measurements to infer ultraviolet inhibition for rates of carbon fixation until there is a greater understanding of the coupling of carbon metabolism to PSII activity for natural populations. Despite these current limitations, fluorescence-based technologies represent powerful tools for studying the impact of the ozone hole on natural populations on spatial/temporal scales not possible using conventional productivity techniques. 55 refs., 11 figs., 2 tabs.},
doi = {10.1111/j.0022-3646.1995.00703.x},
journal = {Journal of Phycology},
number = 5,
volume = 31,
place = {United States},
year = 1995,
month =
}
  • The goals of the Icecolors 1993 expedition were (1) to develop a space/time climatology of incident and penetrating spectral irradiance for the southern oceans, (2) to quantify the ultraviolet (UV) dependency of primary production for pelagic and substrate-associated antarctic phytoplankton communities, and (3) to determine the UV inhibition effects on key target sites. The study was conducted at Palmer Station, Antarctica, prior to the opening of the ozone `hole` and during the onset of depletion of ozone, the most severe ever recorded over the Antarctic Peninsula. This paper discusses results from an experiment designed to estimate a biological weight functionmore » for primary production inhibition in Antarctic phytoplankton under natural irradiance. The newly derived function is presented and it is shown that the sensitivity of in situ phytoplankton to ambient UV-B at the end of winter was greater than that measured under artificial light conditions for temperate marine phytoplankton and terrestrial plants. 18 refs., 3 figs.« less
  • A mat-forming cyanobacterium (Phormidium murayi West and West) isolated from an ice-shelf pond in Antarctica was grown under white light combined with a range of UVA and UVB irradiance. The 4-day growth rate decreased under increasing ultraviolet (UV) radiation, with a ninefold greater response to UVB relative to UVA. In vivo absorbance spectra showed that UVA and to a greater extent UVB caused a decrease in phycocyanin/chlorophyll a and an increase in carotenoids/chlorophyll a. The phycocyanin/chlorophyll a ratio was closely and positively correlated to the UVB-inhibited growth rate. Under fixed spectral gradients of UV radiation, the growth inhibition effect wasmore » dominated by UVB. However, at specific UVB irradiances the inhibition of growth depended on the ratio of UVB to UVA, and growth rates increased linearly with increasing UVA. These results are consistent with the view that UVB inhibition represents the balance between damage and repair processes that are each controlled by separate wavebands. They also underscore the need to consider UV spectral balance in laboratory and field assays of UVB toxicity. 49 refs., 6 figs.« less
  • The main forms of terrestrial life in the cold, desolate Ross Desert of Antarctica are lichen-dominated or cyanobacterium-dominated cryptoendolithic (hidden in rock) microbial communities. Though microbial community biomass (as measured by extractable lipid phosphate) was well within the range of values determined for their microbial communities, community lipid carbon turnover times (calculated from community lipid biomass, rates of community photosynthetic carbon incorporation into lipids versus temperature, and the in situ temperature record) were among the longest on Earth (ca. 20,000 years). When the temperature is above freezing and moisture is present, moderate rates of photosynthesis can be measured. Lichen communitiesmore » had a psychrophilic temperature response (maximal rate of 4.5 ng of C h{sup {minus}1}m{sup {minus}2} at 10C) while cyanobacteria communities had maximal rates at 20 to 30C(3 ng of C h{sup {minus}1} m{sup {minus}2}). These extraordinarily slowly growing communities were not nutrient limited. No significant changes in photosynthetic metabolism simple, tenacious microbial communities demonstrate strategies of survival under conditions normally considered too extreme for life.« less
  • Pure-culture studies were conducted to determine the effect of short-chain aliphatic amines and ammonia on photosynthesis by a green alga, Chlorella ellipsoidea, and a blue-green alga, Anabaena subcylindrica, and on the nitrogenase activity by A. subcylindrica. The aliphatic amines (1 to 5 carbons) and ammonia decreased C. ellipsoidea O/sub 2/ production 50% at concentrations ranging from 1.2 X 10/sup -9/ to 23.5 X 10/sup -9/ ..mu..g free amine N/cell and 160 X 10/sup -9/ ..mu..g free ammonia N/cell, respectively. Amine (1 to 6 carbons) concentrations, ranging from 3.0 X 10/sup -9/ to 25.8 X 10/sup -8/ ..mu..g free amine N/cell,more » decreased A. subcylindrica O/sub 2/ production and N/sub 2/ fixation 50% (as estimated by the acetylene reduction technique). Ammonia concentrations of 12 to 2510 and 14 to 1220 times greater than any single amine concentration were needed to decrease A. subcylindrica O/sub 2/ production or acetylene reduction by 50%, respectively. The effect of the chemical on C. ellipsoidea was reversible and depended on pH and free amine concentration. 20 references, 4 figures, 2 tables.« less
  • Springtime ozone depletion and the resultant increase in ultraviolet-B (UV-B) radiation [280-320 nanometers (nm)] have deleterious effects on primary productivity. To assess damage to cellular components other than the photosynthetic apparatus, we isolated total community DNA from samples in the field before, during, and after the 1993 springtime depletion in stratospheric ozone. The effort was motivated by the concern that the ozone-dependent increases in UV-B radiation may increase DNA damage within primary producers. This increase in damage could result in changes of species composition as well as hereditary changes within species that can influence the competitiveness of these organisms inmore » their natural community. Previous studies have focused on DNA damage in isolated cultures of antarctic phytoplankton that were irradiated with UV-B under lab conditions. These studies clearly indicate variable species sensitivities to the increase in UV-B flux. These studies, however, did not resolve the question of whether such damage occurred in field samples collected from actively mixing, polyphyletic phytoplankton communities. Potential species composition changes and the resultant changes in the trophic dynamics cannot be interpreted in terms of DNA damage unless this damage can be documented in samples isolated under these dynamic natural conditions. 7 refs., 2 figs.« less