Short‐term Effects of Uvb Radiation on Chlorophyll Fluorescence, Biomass, Pigments, and Carbohydrate Fractions in a Benthic Diatom Mat

Underwood, Graham J. C.; Nilsson, Claes; Sundbäck, Kristina; Wulff, Angela

doi:10.1046/j.1529-8817.1999.3540656.x

Cited by 65 publications

(74 citation statements)

References 50 publications

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“…These findings contrast with prior studies of epipelon, where EPS was occasionally less abundant in +UV treatments (Underwood et al 1999, Roux et al 2002. It is possible that periphytic EPS in our study system was relatively more resistant to UV degradation, or that any UV-induced degradation of EPS was offset by increased periphytic biomass or EPS production.…”

Section: Resultscontrasting

confidence: 99%

“…To date, most in situ research on this topic has been conducted in marine intertidal epipelon, where the organisms, primarily diatoms, are motile in the sediments and not attached to hard surfaces. Underwood et al (1999) observed a reduction in EPS and concomitant reductions in epipelon biomass and chlorophyll a under an ambient +15% UV-B treatment. In another epipelon study, EPS was reduced in +W plots as compared to -UV plots, but only on a few sample days (Roux et al 2002).…”

Section: Introductionmentioning

confidence: 87%

“…Even within the same water body, the algae of the phytoplankton, epipelon (the sediment-associated microbial community), and periphyton associated with hard surfaces can have different responses to ultr&iolet (UV) radiation due to their different growth habits and escape abilities (Vinebrooke and Leavitt 1999). Unlike motile epipelic cyanobacterial filaments (Bebout and Garcia-Pichel 1995) and diatoms (Underwood et al 1999), which can migrate downwards in the sediments, or phytoplankton, which can sink deeper in the water column to where UV radiation is more attenuated, organisms in epilithic or epiphytic periphyton have no means of physical escape from UV radiation. Thus, shallow periphyton on hard surfaces may be the aquatic microbial community most directly affected by UV radiation.…”

Section: Introductionmentioning

confidence: 99%

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Effects of UV Radiation on Wetland Periphyton: Algae, Bacteria, and Extracellular Polysaccharides

Thomas¹,

Kuehn²,

Francoeur³

2009

Journal of Freshwater Ecology

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To study the effects of UV radiation on wetland periphyton, glass substrata were placed under acrylic mesocosms in a small freshwater marsh in Michigan, USA. One treatment excluded light in the UV range (<400nm), and another allowed the passage of all light. Substrata were sampled on four dates during August and September 2004. Chlorophyll a, algal community composition, ash-free dry mass, bacterial density and viability, and total extracellular polysaccharide (EPS) content were measured. Algal biomass, algal community composition, bacterial abundance, and ash-free dry mass were relatively insensitive to UV treatment; however, the proportion of non-viable bacteria (p = 0.006) and area-specific EPS content (p = 0.025) were significantly greater in the UVexposed treatment. These results suggest that ambient levels of UV can damage periphytic bacteria and may cause corresponding functional changes within naturally occurring periphytic communities.

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Section: Resultscontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of UV Radiation on Wetland Periphyton: Algae, Bacteria, and Extracellular Polysaccharides

Thomas¹,

Kuehn²,

Francoeur³

2009

Journal of Freshwater Ecology

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“…Adaptation processes include protection and repair mechanisms. Avoidance of UV-B includes the ability to move away from the harmful radiation (Underwood et al 1999), and on community level, ''selfshading'' i.e., cells deeper in the assemblages get protection through light absorption by cells at the surface (Blanchard and Gall 1994). In a hard bottom microphytobenthic community the adaptation processes are more important because a movement deeper into the sediment is not possible.…”

Section: Introductionmentioning

confidence: 99%

Grazing and UV radiation effects on an Antarctic intertidal microalgal assemblage: a long-term field study

Zacher

Hanelt²,

Wiencke

et al. 2007

Polar Biol

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A 15 week field experiment (austral summer Nov-Mar) was carried out in an intertidal hard bottom platform in Antarctica (King George Island). To test whether grazing and ultraviolet radiation (UVR) influenced the succession of a benthic microalgal assemblage, a twofactorial design was used (1) ambient radiation, >280 nm; (2) ambient minus UV-B, >320 nm; (3) ambient minus UVR, >400 nm versus grazer-no grazer). On four sampling occasions microalgae were identified, counted and carbon contents were calculated. The assemblage was dominated by the diatom genera Navicula and Cocconeis. Biomass was generally low in all treatments but was significantly reduced by grazing throughout the experiment. No significant UV effects were found. Grazer absence particularly favoured diatoms of the genus Cocconeis. We conclude that the Antarctic microalgal assemblage was unaffected by present day UVR whereas grazers acted as important drivers on the intertidal microalgal community structure.

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“…Such systems have been designed for terrestrial experiments (Mepsted et al 1996) and have recently been implemented by aquatic ecologists (Underwood et al 1999).…”

Section: Discussionmentioning

confidence: 99%

The effects of ultraviolet radiation on the planktonic community of a shallow, eutrophic estuary: results of mesocosm experiments

Forster

Schubert

2001

Helgol Mar Res

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This paper describes the results of pelagic mesocosm experiments designed to test the effects of enhanced and reduced ultraviolet radiation (UV) on the planktonic community of a Baltic Sea estuary. The Darss-Zingst estuary consists of a series of brackish lagoons with high concentrations of chlorophyll and dissolved organic matter. The shallow depth of the estuary ensures that organisms in the water are regularly exposed to high levels of photosynthetically active radiation (PAR) and UV. During the summer of 1995 and 1996, four 1-m 3 mesocosms were filled with water from the mid-point of the estuary. Each compartment was equipped with a pump to simulate natural rates of windinduced vertical mixing. The mesocosms were hung in the estuary from a floating raft and were shielded from above by filters to give the spectral treatments PAR only, PAR+UV-A, and PAR+UV-A+UV-B. Enhanced levels of UV-B, i.e. twice that of midday sunlight, were provided in a further treatment by artificial sunlamps. Experiments were conducted for periods of 3-14 days. No significant effects of enhanced or reduced UV-B were observed on chlorophyll a concentrations or photosynthetic performance, although the PAR-only treatment did show higher final chlorophyll concentrations in two of the trials. Phytoplankton pigment composition was measured by in vivo absorption and fluorescence excitation spectra, and was similar in all mesocosm treatments indicating that there were no major differences in functional group composition. Bacterial secondary production rates as measured by thymidine incorporation increased with time in all mesocosms, probably due to enhanced production of phytoplankton exudate. There was evidence for a small depression of secondary production by enhanced UV-B, but only on certain days. Microzooplankton generally increased in all mesocosms to population densities higher than those observed in the estuary, and tended to reach higher final values in the mesocosms exposed to UV. It is concluded that vertical mixing which reduces the residence time of planktonic organisms in the surface layers, and high concentrations of chromophoric, dissolved organic matter, which greatly reduce the penetration of UV-B, combined to protect the planktonic community from UV-B damage.

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Short‐term Effects of Uvb Radiation on Chlorophyll Fluorescence, Biomass, Pigments, and Carbohydrate Fractions in a Benthic Diatom Mat

Cited by 65 publications

References 50 publications

Effects of UV Radiation on Wetland Periphyton: Algae, Bacteria, and Extracellular Polysaccharides

Effects of UV Radiation on Wetland Periphyton: Algae, Bacteria, and Extracellular Polysaccharides

Grazing and UV radiation effects on an Antarctic intertidal microalgal assemblage: a long-term field study

The effects of ultraviolet radiation on the planktonic community of a shallow, eutrophic estuary: results of mesocosm experiments

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