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.

Minicosm design: Three successive experiments to a maximum incubation of 14 days were performed from mid November to early January in the summer of 2002/03 in a temperature controlled shipping container housing six 500 L polythene tanks or minicosms. Domes of UV transmissive PMMA in the roof of the container directly above the minicosms allowed ambient sunlight to be reflected to the tanks through tubes of anodised aluminium. These tubes reflected greater than 96% of the incident radiation irrespective of wavelength. Light perturbation to each minicosm was achieved by screening materials that attenuated UV wavelengths. UV stabilised polycarbonate removed wavelengths shorter than 400 nm, transmitting only photosynthetically active radiation (PAR) and provided the control treatment (PAR). In minicosm 2, a mylar screen removed UVB wavelengths (280 - 320 nm), providing a treatment (UVA) with PAR and UVA. Minicosms 3, 4 and 5 (UVB1, 2 and 3 respectively) were screened by borosilicate glass of 9, 5, and 3 mm thickness, transmitting ambient light (including UVR) at the equivalent water depths (ED, k=0.4) of 7.15, 5.38 and 4.97 meters respectively. Minicosm 6 (UVB4) was screened with PMMA that transmitted ambient light at an ED of 4.43 m. Light measurements: Measurements of downwelling UV and PAR were obtained using biometer and Licor sensors mounted on the roof of the minicosm container. A Macam, double grating spectroradiometer measured the spectral irradiance on the roof of the container. This was then weighted with the erythemal action spectrum and correlated to that obtained by the UV biometer. The Macam was used to measure the spectral irradiance at the cross of the UV biometer. The spectral intensity of light wavelengths were measured laterally and vertically in the minicosm screened only by UV-transmissive PMMA irradiance. These measurements were used to model the light field within the minicosm. In all other light treatments the Macam measured the spectral irradiance immediately below the water surface and in the centre of the minicosm. The model was then used to predict the spectral distribution and intensity of other light treatments. These measurements were repeated at interval throughout the season to determine whether solar elevation influenced transmission of ambient downwelling irradiance to the minicosms. UV and PAR sensors fixed to the outside of the minicosm container, together with the modelled light climates within each minicosm beneath each light treatment, predicted the quantify the light to which each experimental treatment was exposed. This work was conducted as part of ASAC project 2210. The download file contains three excel spreadsheets, plus three accompanying word documents which provide detailed methods used in the collection of these data, plus more information about the experiments. The fields in this dataset are: Day Treatment UVA UVB PAR - photosynthetically active radiation

Minicosm design: Three successive experiments to a maximum incubation of 14 days were performed from mid November to early January in the summer of 2002/03 in a temperature controlled shipping container housing six 500 L polythene tanks or minicosms. Domes of UV transmissive PMMA in the roof of the container directly above the minicosms allowed ambient sunlight to be reflected to the tanks through tubes of anodised aluminium. These tubes reflected greater than 96% of the incident radiation irrespective of wavelength. Light perturbation to each minicosm was achieved by screening materials that attenuated UV wavelengths. UV stabilised polycarbonate removed wavelengths shorter than 400 nm, transmitting only photosynthetically active radiation (PAR) and provided the control treatment (PAR). In minicosm 2, a mylar screen removed UVB wavelengths (280 - 320 nm), providing a treatment (UVA) with PAR and UVA. Minicosms 3, 4 and 5 (UVB1, 2 and 3 respectively) were screened by borosilicate glass of 9, 5, and 3 mm thickness, transmitting ambient light (including UVR) at the equivalent water depths (ED, k=0.4) of 7.15, 5.38 and 4.97 meters respectively. Minicosm 6 (UVB4) was screened with PMMA that transmitted ambient light at an ED of 4.43 m. Light measurements: Measurements of downwelling UV and PAR were obtained using biometer and Licor sensors mounted on the roof of the minicosm container. A Macam, double grating spectroradiometer measured the spectral irradiance on the roof of the container. This was then weighted with the erythemal action spectrum and correlated to that obtained by the UV biometer. The Macam was used to measure the spectral irradiance at the cross of the UV biometer. The spectral intensity of light wavelengths were measured laterally and vertically in the minicosm screened only by UV-transmissive PMMA irradiance. These measurements were used to model the light field within the minicosm. In all other light treatments the Macam measured the spectral irradiance immediately below the water surface and in the centre of the minicosm. The model was then used to predict the spectral distribution and intensity of other light treatments. These measurements were repeated at interval throughout the season to determine whether solar elevation influenced transmission of ambient downwelling irradiance to the minicosms. UV and PAR sensors fixed to the outside of the minicosm container, together with the modelled light climates within each minicosm beneath each light treatment, predicted the quantify the light to which each experimental treatment was exposed. This work was conducted as part of ASAC project 2210. The download file contains three excel spreadsheets, plus three accompanying word documents which provide detailed methods used in the collection of these data, plus more information about the experiments. The fields in this dataset are: Day Treatment Carbon Hydrogen Nitrogen C:N ratio

From the abstract of some of the papers: It has been suggested that increased springtime UVB radiation caused by stratospheric ozone depletion is likely to reduce primary production and induce changes in the species composition of Antarctic marine phytoplankton. Experiments conducted at Arthur Harbour in the Antarctic Peninsula revealed a reduction in primary productivity at both ambient and increased levels of UVB. Laboratory studies have shown that most species in culture are sensitive to high UVB levels, although the level at which either growth or photosynthesis is inhibited is variable. Stratospheric ozone depletion, with resultant increased springtime UVB irradiance, has been occurring with increasing severity since the late 1970's. Thus the phytoplankton community has already experienced about 20 years' exposure to increasing levels of UVB radiation. Here we present analyses of diatom assemblages from high-resolution stratigraphic sequences from anoxic basins in fjords of the Vestfold HIlls, Antarctica. We find that compositional changes in the diatom component of the phytoplankton community over the past 20 years cannot be distinguished from long-term natural variability, although there is some indication of a decline in the production of some sea-ice diatoms. We anticipate that our results are applicable to other Antarctic coastal regions, where thick ice cover and the timing of the phytoplankton bloom protect the phytoplankton from the effects of increased UVB radiation. Growth rate, survival, and stimulation of the production of UV-B (280 to 320 nm) absorbing compounds were investigated in cultures of five commonly occurring Antarctic marine diatoms exposed to a range of UV-B irradiances. Experimental UV-B exposures ranged from 20 to 650% of the measured peak surface irradiance at an Antarctic coastal site (0.533 J per square metre per second). The five diatom species (Nitzschia lecointei, Proboscia alata, P. inermis, Thalassiosira tumida and Stellarima microtrias) appear capable of surviving two to four times this irradiance. In contrast to Phaeocystis cf. pouchetti, another major component of the Antarctic phytoplankton, the concentrations of pigments with discrete UV absorption peaks in diatoms were low and did not change significantly under increasing UV-B irradiance. Absorbance of UV-B by cells from which pigments had been extracted commonly exceeded that of the pigments themselves. Most of this absorbance was due to oxidisable cell contents, with the frustule providing the remainder. Survival of diatoms did not correlate with absorption by either pigments, frustules or oxidisable cell contents, indicating that their survival under elevated UV-B irradiances results from processes other than screening mechanisms. Springtime UV-B levels have been increasing in Antarctic marine ecosystems since the 1970's. Effects on natural phytoplankton and sea-ice algal communities, however, remain unresolved. At the Marginal Ice Edge Zone, enhanced springtime UV-B levels coincide with a shallow, stratified water column and a major phytoplankton bloom. In these areas it is possible that phytoplankton growth and survival is adversely impacted by enhanced UV-B. In coastal areas, however, the sea ice, which attenuates most of the UV-B before it reaches the water column, remains until December/January, by which time UV-B levels have returned to long-term seasonal averages. Phytoplankton from these areas are unlikely to show long-term changes resulting from the hole in the ozone layer. Fjords of the Vestfold Hills, eastern Antarctica, have anoxic basins which contain high-resolution, unbioturbated sedimentary sequences. Diatom assemblages from these sequences reflect the diatom component of the phytoplankton and sea-ice algal assemblages at the time of deposition. Twenty-year records from these sequences show no consistent record of change in species composition, diversity or species richness. Six-hundred-year records from the same area also show changes in species abundance greater than those seen in the last 20 years. From these records it can be seen that recent changes in diatom abundances generally fall within the limits of natural variability and there is little evidence of recent changes that might be associated with UV-B-induced change.

Antarctic marine diatoms are sensitive to environment change. This project will determine the environmental niches occupied by key diatom species in Antarctic sediments. This will allow climate changes in the past to be interpreted from Holocene sediments and future changes in diatom biogeography to be predicted. Environmental manipulation and competition experiments using diatoms will identify the response of key taxa to environment modification. Understanding the environmental factors governing their distribution and natural variability will provide a basis to interpret palaeo-environment records, and allow predictions how this temperature-sensitive ecosystem will respond to future change. Diatoms for the experiments were collected in 2002 (Aurora Australia, Voyage 1) and 2003 (Aurora Australis, Voyage 1). On each occasion water from the ship's online seawater tap was filtered through a 20 micrometre plankton net for up to one hour into a sample jar. A portion of the sample was preserved in lugol's iodine for later phytoplankton analysis, and the rest of the sample maintained alive in the dark in seawater at a constant low temperature. The live sample is maintained at the AAD for culturing and environment manipulation and competition experiments. Project 2302 Twenty-two water samples were collected from 24/10/02 to 11/11/02, in open seawater between 53 degrees 50 degrees S and 65 degrees 50 degrees S. At each site, the following were recorded from the ship's data logger: latitude, longitude, date, UCT time, local time, water depth, salinity, water temperature, chlorophyll A, UV radiation, and conductivity.

Environmental manipulation and competition experiments on cultured and natural diatoms will identify the response of key taxa to environment modification. Understanding the environmental factors governing diatom distribution and natural variability will provide a basis to interpret palaeo-environment records, and allow predictions how this temperature-sensitive ecosystem will respond to future change. Environmental manipulation and competition experiments using diatoms will identify the response of key taxa to environment modification. Understanding the environmental factors governing their distribution and natural variability will provide a basis to interpret palaeo-environment records, and allow predictions how this temperature-sensitive ecosystem will respond to future change. Diatoms for the experiments were collected in 2002 (Aurora Australia, Voyage 1) and 2003 (Aurora Australis, Voyage 1). On each occasion water from the ship's online seawater tap was filtered through a 20 micrometre plankton net for up to one hour into a sample jar. A portion of the sample was preserved in lugol's iodine for later phytoplankton analysis, and the rest of the sample maintained alive in the dark in seawater at a constant low temperature. The live sample is maintained at the AAD for culturing and environment manipulation and competition experiments. Project 2364 Twelve water samples were collected from 23/10/03 to 27/10/03, in open seawater between 60 degrees 45' S and 50 degrees 02' S. At each site, the following data were recorded from the ship's data logger: latitude, longitude, UTC time, local time, water depth, salinity, water temperature, fluorescence, UVB, and conductivity.

Increased ultraviolet radiation (UV-A and/or UV-B) may impact on the establishment and structure of a shallow water benthic invertebrate assemblages. A global experiment in more than 8 countries, using an identical methodology (transparent UV filters) will add significantly to our understanding of the impacts of anthropogenically induced global change on natural systems. To appraise the effects of increased UVR on shallow marine benthic assemblages, five experimental rafts were deployed in protected bays west of Shirley Island near Casey Station, Antarctica (66.16oS 110.30oE). Each raft consisted of eight experimental units, each of which contained a colonization panel (ceramic tile) positioned horizontally and submerged 4-6 cm underwater. Irradiation treatments were randomly assigned to each unit with the use of UV cut-off filters. The treatments were as follows: No UVR (transmits photosynthetically active radiation or PAR, 400-700nm), No UVB (transmits PAR + UVA, 320-700nm), Perspex (full spectrum, 280-700nm, procedural control), or No filter (full spectrum, treatment control). In addition there were three levels of consumer treatments: With consumption (container sides removed), without consumption (container sides perforated with 4 mm holes), and a control (3 sides perforated, 1 side removed). After seven weeks tiles were removed to the laboratory for examination. All tiles were dominated by diatoms and no sessile invertebrates were apparent. The first trial has been completed, but several other panels are still in place. A conference will be held in early 2002 between participating countries to discuss results and findings. The 2001\2002 summer season consisted of experimental designs divided up into three separate projects. The aims were all to provide a corrollary to the previous seasons data. Project 1 consisted of the extraction and redeployment of settlement depth arrays situated in Geoffrey's Bay and Hollin Island Channel. Due to prevailing weather conditions resulting in limited boating hours and diving program, only one array was retrieved. On inspection of the array it was decided to deploy further replicates to gain a better temporal understanding of the communities. Projects 2 and 3 consisted of a similar experimental design, however monitoring the shallower depths of settlement (depths of 1m and 2m below sea level) for a period of one month. Project 2 consisted of arrays with two depths and 2 panels per depth, triple replicated, under the icesheet in O'Brien Bay and Shirley Channel, with a substrate depth of 20m. Diatom samples are to be analyzed in Australia. Project 3 was of a similar design to project 2 though it was measuring recruitment in shallow open water. The two sites consisted of Noonan Cove and Geoffrey's Bay at substrate depths of 5m. These tiles are also to be analyzed on return to Australia. There were 5 rafts used in this study - they are listed as R1 to R5 there were two factors in the design -(i) predator access: Caged (C) Half caged (H) and Open (O) and ii) UV exposure: Perspex (P), Macrolon (M), No filter (N) and Film + perspex (F). A list of the diatoms found on the settlement panels is provided at the URL below. The fields in this dataset are: Species Sample