| |
Records |
Links  |
|
Author |
Gomez, I.; Wiencke, C.; Thomas, D.N. |
|
| |
Title |
Variations in photosynthetic characteristics of the Antarctic marine brown alga Ascoseira mirabilis in relation to thallus age and size |
Type |
Journal Article |
| |
Year |
1996 |
Publication |
European Journal of Phycology |
Abbreviated Journal |
Eur J Phycol |
|
| |
Volume |
31 |
Issue |
2 |
Pages |
167-172 |
|
| |
Keywords |
photosynthesis: thallus: carbon fixation; growth curves; algae; age; Thalli; marine flora; Ascoseira mirabilis; Antarctica |
|
| |
Abstract |
Growth, photosynthesis, dark respiration, chlorophyll a (Chl a) content and dry weight were measured in 2- and 3-year-old plants of Ascoseira mirabilis (Ascoseirales), cultivated in the laboratory under changing daylengths which matched the seasonal variations in the Antarctic. Determinations were made in four thallus regions. Growth of A. mirabilis was seasonal, with higher rates in spring. Parameters such as net photosynthesis (P sub(max)), photosynthetic efficiency ( alpha ), both measured on a fresh weight (FW) basis, and dry weight content, showed significant age- and size-dependent variations. In contrast, no variations were observed in dark respiration, initial light-saturating point of photosynthesis (I sub(k)) and Chl a contents. P sub(max) had maximum values close to 16.5 mu mol O sub(2)/g super(1) FW/h in 2-year-old plants, whereas in 3-year-old plants maximum values of 8 mu mol O sub(2)/g FW/h were determined. The alpha -values reached maximum rates of 1.4 and 0.6 mu mol O sub(2)/g FW/h/( mu mol photons/m super(2)/s) in 2- and 3-year-old plants, respectively. Light compensation point (I sub(c)), dry weight ratios and Chl a contents varied significantly along the length of the blade. Maximum dry:fresh weight ratios were observed in the basal region, with values close to 18%. Distal regions of the 3-year-old plants had significantly higher dry weight content than 2-year-old plants (17.5% and 13%, respectively). Chl a concentrations increased towards the middle regions of the thallus to values close to 0.35 mg Chl a/g FW. The results indicate that some morpho-functional processes in A. mirabilis, especially net photosynthesis and photosynthetic efficiency, are governed by age of the plant, thereby reflecting differences in biomass allocation and size. Our data also confirm the previously demonstrated relationship between growth and seasonal physiological activity that allows A. mirabilis to survive under the low light conditions prevailing in the Antarctic. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0967-0262 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
growth curves; size; Thalli; marine flora; thallus |
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Gomez++1996 |
Serial |
737 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Granskog, M.A.; Kaartokallio, H.; Thomas, D.N.; Kuosa, H. |
|
| |
Title |
Influence of freshwater inflow on the inorganic nutrient and dissolved organic matter within coastal sea ice and underlying waters in the Gulf of Finland (Baltic Sea) |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Estuarine, Coastal and Shelf Science |
Abbreviated Journal |
Estuar Coast Shelf Sci |
|
| |
Volume |
65 |
Issue |
1-2 |
Pages |
109-122 |
|
| |
Keywords |
coastal oceanography; sea ice; river plumes; estuarine chemistry; nutrients (mineral); dissolved organic matter; Baltic Sea |
|
| |
Abstract |
A study was conducted to measure the biogeochemical characteristics of freshwater plumes underlying Baltic Sea land-fast ice, and the overlying sea ice. A 40-km long transect was conducted in the northern Baltic Sea in March 2003, following a freshwater plume from its source into the fully mixed open-sea area. The spreading of river outflow below the ice resulted in a well-stratified low-salinity surface layer further out than normally occurs in the open-water period. The freshwaters were high in dissolved organic matter (DOC, DON and CDOM), and inorganic nutrients (ammonium, nitrate and silicate), although the levels of phosphate were low. In general these parameters changed concurrently with salinity in such a way that mixing was conservative. The characteristics of the ice varied from the freshwater source to the open water, with increasing salinity and brine volumes (porosity) occurring in the more open-sea stations. Coinciding with the changes in ice properties there was an increase in sea-ice algal growth in the more marine stations along the transect. Biological activity in the ice was largely confined to bottom ice assemblages. In contrast to the conditions in the underlying water, no relationship between salinity, inorganic nutrients and organic matter was observed in the ice. In particular ammonium, phosphate, DOC and DON were present in excess of those levels predicted from the dilution curves, indicating the presence of considerable DOM production by ice assemblages, inorganic nutrient uptake and remineralization within the ice. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
Academic Press |
Place of Publication |
San Diego |
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0272-7714 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
Sampling: Nine stations along a 40km salinity gradient from inner Pojo Bay through the Archipelago to the edge of the open sea |
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Granskog++2005_2 |
Serial |
740 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Herborg, L.-M.; Thomas, D.N.; Kennedy, H.; Haas, C.; Dieckmann, G.S. |
|
| |
Title |
Dissolved carbohydrates in Antarctic sea ice |
Type |
Journal Article |
| |
Year |
2001 |
Publication |
Antarctic Science |
Abbreviated Journal |
Antarct Sci |
|
| |
Volume |
13 |
Issue |
2 |
Pages |
119-125 |
|
| |
Keywords |
Doc; Mcho; Pcho; sea ice; bacteria; carbon cycling; diatoms; dissolved organic carbon; monocarbohydrates; polycarbohydrates |
|
| |
Abstract |
Concentrations of dissolved monocarbohydrates (MCHO) and polycarbohydrates (PCHO) were analysed in a variety of ice habitats from summer Weddell Sea sea ice (surface ponds, ice cores, gap layers and platelet ice). The dissolved organic carbon (DOC) pool in these habitats was also measured and the contribution of carbohydrate to this pool was assessed. The DOC concentrations within all sea ice habitats were high compared to surface seawater concentrations with values up to 958µMC being measured. Total carbohydrates (TCHO) were highest in the ice cores and platelet ice samples, up to 3 1% of the DOC pool, a reflection of the high algal biomass in these two habitat classes. TCHO in the other habitats ranged between 10% and 29% of DOC. The ratios of MCHO to PCHO varied considerably between the ice habitats: in surface ponds and ice cores MCHO was 70% of the TCHO pool, whereas in gap layers and platelet ice there were lower PCHO concentrations resulting in MCHO being 88% of TCHO. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
|
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Herborg++2001 |
Serial |
743 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Schnack-Schiel, S.B.; Thomas, D.N.; Haas, C.; Dieckmann, G.S.; Alheit, R. |
|
| |
Title |
The occurrence of the copepods Stephos longipes (Calanoida) and Drescheriella glacialis (Harpacticoida) in summer sea ice in the Weddell Sea, Antarctica |
Type |
Journal Article |
| |
Year |
2001 |
Publication |
Antarctic Science |
Abbreviated Journal |
Antarctic Sci |
|
| |
Volume |
13 |
Issue |
2 |
Pages |
150-157 |
|
| |
Keywords |
copepods; Drescheriella glacialis; sea ice; seasonality; Stephos longipes |
|
| |
Abstract |
In January to March 1997, a RV Polarstern cruise that transected the Weddell Sea resulted in samples being taken in thick pack ice in the south-eastern Weddell Sea and then along the marginal ice edge towards the Antarctic Peninsula. Several ice types were thus sampled over a wide geographic area during late summer/early autumn. Common features of the first warm period was the occurrence of surface ponds, and that many floes had quasi-continuous horizontal gaps, underlying a layer of ice and metamorphic snow. With the onset of cold air temperatures in late February the gaps rapidly refroze. The calanoid copepod Stephos longipes occurred in all habitats encountered and showed highest numbers in the surface ice in summer, in the gap water during both seasons and in the refrozen gap water in autumn. Nauplii outnumbered copepodids in the surface ice and refrozen gap water, while in the gap water copepodids, mainly stages CI-CIII in summer and CII-CIV in autumn, comprised about 70% of the total population. The harpacticoid species Drescheriella glacialis did not occur in all habitats and was missing in surface ponds and new ice. Nauplii of D. glacialis were rarely found in gapwater, but predominated in the refrozen gaps. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
|
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0954-1020 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Schnack-Schiel++2001_2 |
Serial |
753 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Thomas, D.N.; Lara, R.J.; Haas, C.; Schnack-Schiel, S.B.; Dieckmann, G.S.; Kattner, G.; Nöthig, E.-M.; Mizdalski, E. |
|
| |
Title |
Biological soup within decaying summer sea ice in the Amundsen Sea, Antarctica |
Type |
Book Chapter |
| |
Year |
1998 |
Publication |
Antarctic sea ice: Biological processes, interactions and variability |
Abbreviated Journal |
|
|
| |
Volume |
|
Issue |
|
Pages |
161-171 |
|
| |
Keywords |
Marine biology; Algae; Ice composition; Pack ice; Decomposition; Ecology; Nutrient cycle; Antarctica; Amundsen Sea |
|
| |
Abstract |
In late February 1994, during the ANT XI/3 expedition of R/V Polarstern, ice cores from perennial sea ice were sampled in the Amundsen Sea in areas of dense pack ice. The ice was largely rotten, and a conspicuous feature was the occurrence of thick gaps and voids, often filled with a dark brown slush comprised of loose ice chunks and crystals. These interior ice assemblages were at depths between 1.0 and 1.5 m in 3 to 4 m thick ice floes, and had remarkably rich interior ice algal assemblages (<= 377 µg Chl a L?¹) which were in turn a food source for unusually large numbers of foraminifers (<= 1262 individuals L?¹), the calanoid copepod Stephos longipes (<= 163 individuals L?¹) and harpacticoid copepods (<= 168 individuals L?¹). Analysis of inorganic nutrients (nitrate, phosphate, ammonium, nitrite, and silicate) and dissolved organic carbon (DOC) showed that these were sites of high nutrient supply coupled with high rates of nutrient regeneration. |
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
Washington, DC |
Editor |
Lizotte, M.P.; Arrigo, K.R. |
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
Antarctic Research Series |
Abbreviated Series Title |
|
|
| |
Series Volume |
73 |
Series Issue |
|
Edition |
|
|
| |
ISSN |
|
ISBN |
0-87590-901-9 |
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
no |
|
| |
Call Number |
refbase @ admin @ Thomas++1998 |
Serial |
764 |
|
| Permanent link to this record |
