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The effects of UV-B radiation on the nutritional composition of Antarctic phytoplankton

Entry ID: ASAC_872

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Summary

Abstract: The actual piece of equipment used was an International Light IL 1700Radiometer equipped with broad band detectors to measure PAR, UV-A and erythemal UV-B.

The effects of UV-B radiation on the fatty acid, total lipid and sterol composition and content of three Antarctic marine phytoplankton were examined in a preliminary culture experiment. Exponential growth phase cultures of the diatoms ... Odontella weissflogii and Chaetoceros simplex and the Haptophyte Phaeocystis antarctica were grown at 2 (plus or minus 1)degrees C and exposed to 16.3 (plus or minus 0.7) W.m-2 photosynthetically active radiation (PAR). UV-irradiated treatments were exposed to constant UV-A (4.39 (plus or minus 0.20) W.m-2) and low (0.37 W.m-2) or high UV-B (1.59 W.m-2). UV-B treatments induced species specific changes in lipid content and composition. The sterol, fatty acid and total lipid content and profiles for O. weissflogii changed little under low UV-B when compared with control conditions (PAR alone), but showed a decrease in the lipid content per cell under high UV-B treatment. In contrast, when P. antarctica was exposed to low UV-B irradiance, storage lipids were reduced and structural lipids increased indicating that low UV-B enhanced cell growth and metabolism. P. antarctica also contained a higher proportion of polyunsaturated fatty acids under low UV-B in comparison with PAR irradiated control cultures. The flagellate life stage of P. antarctica died under high UV-B irradiation. However, exposure of P. antarctica to high UV-B irradiance increased total lipid, triglyceride and free fat.

The effect of UV-B irradiances on the lipid content of Antarctic marine phytoplankton is species specific. Changes in ambient UV-B may alter the nutritional quality of food available to higher trophic levels.

EXPERIMENTAL
All measurements of irradiance were made with an International Light IL 1700 Radiometer equipped with broad band detectors to measure PAR, UV-A and erythemal UV-B [14]. A National Institute of Standards and Technology intercomparison package (NIST Test #534/240436-88) was used to calibrate each light sensor.

Unialgal cultures of the diatoms Odontella weissflogii and Chaetoceros simplex were isolated from sea ice collected in Prydz Bay, Antarctica during the 1990/91 austral summer. Phaeocystis antarctica was isolated from Prydz Bay in 1982/83 summer. Cultures of diatoms and Phaeocystis antarctica were maintained in 2 l glass flasks using f/2 growth medium [32] and GP5 medium [33] respectively at a temperature of 2 plus or minus 1 degrees C. Cool white fluorescent lights provided photosynthetically active radiation (PAR) intensity of 17.08 J.m-2.s-1 (84.7 micro E.m-2.s-1), with no UV-B enhancement, on a 12 h light : 12 h dark cycle. Immediately before experimental irradiation, three replicate subsamples of approximately 15 ml were obtained from each parental culture and fixed with Lugols iodine, a known sample volume sedimented, and cells counted over 15 replicate fields using a Labovert inverted microscope. Mean cell concentration and standard deviation were then computed. Each exponential growth phase parental culture was thoroughly mixed and 3 replicate 300 ml Costar polystyrene culture flasks (which completely absorbed wavelengths below 295 nm) established for each light treatment (control, low and high UV exposures). Cultures were irradiated for 24 hours in a 48 hour experimental period (6 h light : 12 h dark : 12 h light : 12 h dark : 6 h light) [14, 23]. Exposures were conducted in a Thermoline controlled environment cabinet at 2 plus or minus 1 degrees C with cool white fluorescent tubes to provide PAR and UV-A (320-400 nm), with UV-B provided by FS20T 12 UV-B Westinghouse sunlamps. PAR and UV-A irradiances were 16.3 plus or minus 0.7 W.m-2 (81.3 plus or minus 3.4 micro E.m-2.s-1) and 4.39 plus or minus 0.20 W.m-2 respectively. The spectral distribution and UV-B irradiance were varied by attenuation with glass filters [5] to provide low (0.37 W.m-2) or high UV-B (1.59 W.m-2). Sensors were each covered by an attenuating glass screen and a single layer of Costar culture flask to measure the experimental irradiances to which the algae were exposed. UV-B irradiances were chosen to reflect less than (74%) and greater than (318%) peak UV-B exposure as measured at an Antarctic coastal site (Casey station, 66 degrees S, [34]).

Following irradiation each culture was well mixed and approximately 15 ml was fixed with Lugols Iodine for subsequent estimation of cell concentration (as above). Chlorotic and greatly vesicularised cells were considered to be dead [23]. The remainder of each experimental culture was filtered through Whatman GF/F filters. On completion of filtration, the filters were stored at -20C overnight before extraction of lipids the following day.

Related URL

Link: VIEW PROJECT HOME PAGE

Description: Public information for ASAC project 872

Geographic Coverage

(Click for Interactive Map)

Spatial coordinates

N: -54.0

S: -70.0

E: 159.0

W: 62.0

Temporal Coverage

Start Date: 1995-09-30

Stop Date: 1996-03-31

Location Keywords

CONTINENT > AUSTRALIA/NEW ZEALAND > AUSTRALIA

CONTINENT > ANTARCTICA

GEOGRAPHIC REGION > POLAR

Science Keywords

ATMOSPHERE > ATMOSPHERIC RADIATION > ULTRAVIOLET RADIATION

OCEANS > OCEAN CHEMISTRY > ORGANIC CARBON

BIOSPHERE > AQUATIC ECOSYSTEMS > PLANKTON > PHYTOPLANKTON

BIOSPHERE > AQUATIC ECOSYSTEMS > COASTAL HABITAT

ISO Topic Category

BIOTA

CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

GEOSCIENTIFIC INFORMATION

OCEANS

Instrument

RADIOMETERS

Quality Values provided in temporal and spatial coverage are approximate only.

Access Constraints A copy of one of the referenced papers is available for download to AAD personnel only.

Use Constraints This data set conforms to the PICCCBY Attribution License
(http://creativecommons.org/licenses/by/3.0/).

Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_872 when using these data.

Ancillary Keywords

ALGAE

ANTARCTIC

Data Set Progress

COMPLETE

Data Center

Australian Antarctic Data Centre, Australia

Data Center URL: http://data.aad.gov.au

Data Center Personnel
Name: DATA OFFICER AADC Phone: +61 3 6232 3244 Fax: +61 3 6232 3351 Email: metadata at aad.gov.au Contact Address: Australian Antarctic Division 203 Channel Highway City: Kingston Province or State: Tasmania Postal Code: 7050 Country: Australia

Distribution

Distribution Media: HTTP

Distribution Size: 188 kb

Distribution Format: pdf

Fees: Free

Personnel

ANDREW TIMOTHY DAVIDSON

Role: TECHNICAL CONTACT

Phone: +61 3 6232 3444

Fax: +61 6232 3351

Email: andrew.davidson at aad.gov.au

Contact Address:

Australian Antarctic Division

203 Channel Highway

City: Kingston

Province or State: Tasmania

Postal Code: 7050

Country: Australia

JENNIFER HELEN SKERRATT

Role: INVESTIGATOR

Role: DIF AUTHOR

Phone: +61 3 6232 5279

Fax: +61 3 6224 0530

Email: Jenny.skerratt at utas.edu.au

Contact Address:

CSIRO Marine and Atmospheric Research

GPO BOX 1538

City: Hobart

Province or State: Tasmania

Postal Code: 7001

Country: Australia

Publications/References

McMinn A. Skerratt J. Trull T. Ashworth C. Lizotte M. (1999), Nutrient stress gradient in the bottom 5 cm of fast ice, McMurdo Sound, Antarctica., Polar Biology, 21, 4, 220-227, doi:DOI: 10.1007/s003000050356

Skerratt JH. Davidson AD. Nichols PD. Mcmeekin TA. (1998), Effect of uv-b on lipid content of three Antarctic marine phytoplankton, Phytochemistry, 49, 4, 999-1007

Creation and Review Dates

DIF Creation Date: 2000-08-08

Last DIF Revision Date: 2012-01-13

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