This work is a French contribution to the
SO-JGOFS program. It was supported by the French Polar
Institute (IPEV) and the INSU-CNRS. This research was
partly financed by the Polonium Program of scientific cooperation
between Poland and France. It was also partly conducted
under grants A4/DD/B14 and EV/12/7E within the
Scientific Research on the Antarctic supported by the Belgian
Office for Scientific, Technical and Cultural Affairs.
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[en] A mesoscale study was conducted in January and February 1999 in the Crozet Basin frontal zones (43degrees50' to 45degrees20'S, 61degrees00' to 64degrees30'E) within the southernmost and easternmost convergence area of the Antarctic Circumpolar Current (ACC) and the Agulhas Return Current (ARC). Distribution of biogeochemical parameters was strongly linked to the merged Subtropical (STF) and Subantarctic (SAF) Fronts which mark the border between the cold and less saline subantarctic waters and the warm and more saline subtropical waters. This survey took place during a post-bloom period. Chlorophyll a concentrations were low throughout the study area ranging from 0.2 mug l(-1) in the Polar Frontal Zone (PFZ) to 0.4 mug l(-1) in the Subtropical Zone (STZ). Maximum chlorophyll a values (0.8 mug l(-1)) associated with an increase in biogenic silica concentration (from 0.03 to 0.34 muM) and a diatom peak (1.2 x 10(5) cells l(-1)) were encountered in the northeastern part of the STF edge. Despite northwardly decreasing concentrations of nitrates from 14 muM in the PFZ to 6 PM in the STZ, they were not the main factor limiting phytoplankton growth. Low silicic acid (mean = 0.6 muM) could have limited diatom development in the PFZ and the STZ where diatom numbers were low. In STZ waters, where average diatom numbers were highest, various species of Nitzschia and Thalassiothrix were common, but Pseudonitzschia spp. were dominant. Throughout the survey area, pico- and nano-sized cells dominated the phytoplankton assemblage, and their number was the highest in the STZ. Cyanobacteria, only present in subtropical waters >12.5degreesC, were the major component of the picoplankton size-fraction. While dinoflagellate numbers were low in the Subantarctic Zone (SAZ), their abundance and species numbers increased in the STZ, where Oxytoxum laticeps became dominant and several further large-size species of Prorocentrum, Ceratium and Gymnodinium appeared in addition to those at the STF. The distribution of different biogeochemical parameters suggests that the Crozet Basin frontal region is a non-exporting system at the end of summer. During this post-bloom period, biological activity is low and phytoplankton growth severely limited. This is evidenced by the weak dependence of the partial pressure of carbon dioxide (pCO(2)) on biological activity and the importance of the air-sea exchange in maintaining pCO(2) close to saturation.
Barange M, Pakhomov EA, Perissinotto R, Froneman PW, Verheye HM, Taunton-Clark J, Lucas MI (1998) Pelagic community structure of the Subtropical Convergence region south of Africa and in the mid-Atlantic Ocean. Deep-Sea Res Part I 45:1663-1687
Bathmann UV, Scharek R, Klaas C, Dubischar CD, Smetacek V (1997) Spring development of phytoplankton biomass and composition in major water masses of the Atlantic sector of the Southern Ocean. Deep-Sea Res Part II 44:51-67
Billen G, Becquevort S (1991) Phytoplankton-bacteria relationship in the Antarctic marine ecosystem. Polar Res 10:245-253
Blain S, Tréguer P, Belviso S, Bucciarelli E and 8 others (2001) A biogeochemical study of the island mass effect in the context of the iron hypothesis: Kerguelen Islands, Southern Ocean. Deep-Sea Res Part I 48:163-187
Blain S, Sedwick PN, Griffiths FB, Quéguiner B, Bucciarelli E, Fiala M, Pondaven P, Tréguer P (2002) Quantification of algal iron requirements in the Subantarctic Southern Ocean (Indian sector). Deep-Sea Res Part II 49:3255-3273
Boyd PW, Law CS (2001) The Southern Ocean Iron Release Experiment (SOIREE) - introduction and summary. Deep-Sea Res Part II 48:2425-2438
Bradford-Grieve JM, Chang FH, Gall M, Pickmere S, Richards F (1997) Size-fractionated phytoplankton standing stocks and primary production during austral winter and spring 1993 in the Subtropical Convergence region near New Zealand. NZ J Mar Freshw Res 31:201-224
Bradford-Grieve JM, Boyd PW, Chang FH, Chiswell S and 5 others (1999) Pelagic ecosystem structure and functioning in the Subtropical Front region east of New Zealand in austral winter and spring 1993. J Plankton Res 21:405-428
Clementson LA, Parslow JS, Griffiths FB, Lyne VD and 6 others (1998) Controls on phytoplankton production in the Australasian sector of the subtropical convergence. Deep-Sea Res Part I 45:1627-1661
Copin-Montégut C (1988) A new formula for the effect of temperature on the partial pressure of carbon dioxide in seawater. Mar Chem 25:29-37
Copin-Montégut C (1989) A new formula for the effect of temperature on the partial pressure of carbon dioxide in seawater: Corrigendum. Mar Chem 27:143-144
Dafner EV, Mordasova NV (1994) Influence of biotic factors on the hydrochemical structure of surface water in the Polar Frontal Zone of the Atlantic Antarctic. Mar Chem 45:137-148
Davidson AT, Marchant HJ (1992) Protist abundance and carbon concentration during a Phaeocystis-dominated bloom at an Antarctic coastal site. Polar Biol 12:387-395
Deacon GER (1982) Physical and biological zonation in the Southern Ocean. Deep-Sea Res 29:1-15
Dower KM, Lucas MI (1993) Photosynthesis-irradiance relationship and production associated with a warm-core ring shed from the Agulhas Retroflection south of Africa. Mar Ecol Prog Ser 95:141-154
El-Sayed SZ, Weber LH (1982) Spatial and temporal variations in phytoplankton biomass and primary productivity in the southwest Atlantic and Scotia Sea. Polar Biol 1:83-90
Fiala M, Kopczynska EE, Jeandel C, Oriol L, Vetion G (1998a) Seasonal and interannual variability of size-fractionated phytoplankton biomass and community structure at station Kerfix, off the Kerguelen Islands, Antarctica. J Plankton Res 20:1341-1356
Fiala M, Semeneh M, Oriol L (1998b) Size-fractionated phytoplankton biomass and species composition in the Indian sector of the Southern Ocean during austral summer. J Mar Syst 17:179-194
Fiala M, Machado MC, Oriol L (2002) Phytoplankton distribution in the Indian sector of the Southern Ocean during spring. Deep-Sea Res Part II 49:1867-1880
Fouilland E, Descolas-Gros C, Courties C, Pons V (1999) Autotrophic carbon assimilation and biomass from size-fractionated phytoplankton in the surface waters across the subtropical frontal zone (Indian Ocean). Polar Biol 21:90-96
Frankignoulle M, Borges A, Biondo R (2001) A new design of equilibrator to monitor carbon dioxide in highly dynamic and turbid environments. Water Res 35:1344-1347
Franks PJS (1992) Phytoplankton blooms at fronts: patterns, scales, and physical forcing mechanisms. Rev Aquat Sci 6:121-137
Froneman PW, McQuaid CD, Perissinotto R (1995) Biogeographic structure of microphytoplankton assemblages of the south Atlantic and Southern Ocean during austral summer. J Plankton Res 17:1791-1802
Froneman PW, McQuaid CD, Laubscher RK (1999) Size-fractionated primary production studies in the vicinity of the Subtropical Front and an adjacent warm-core eddy south of Africa in austral winter. J Plankton Res 21:2019-2035
Froneman PW, Laubscher RK, McQuaid CD (2001) Size-fractionated primary production in the south Atlantic and Atlantic sectors of the Southern Ocean. J Plankton Res 23:611-622
Furuya K, Hasumoto H, Nakai T, Nemoto T (1986) Phytoplankton in the Subtropical Convergence during the austral summer: community structure and growth activity. Deep-Sea Res 33:621-630
Gall M, Hawes I (1999) Predicting rates of primary production in the vicinity of the Subtropical Convergence east of New Zealand. NZ J Mar Freshw Res 33:443-455
Gamberoni L, Geronimi J, Jeanin PF, Murail JF (1982) Study of frontal zones in the Crozet-Kerguelen region. Oceanol Acta 6:289-299
Gibson JAE, Garrick RC, Burton HR (1990) Seasonal fluctuation of bacterial numbers near the Antarctic continent. Proc Natl Inst Polar Res (NIPR) Symp Polar Biol 3:16-22
Hall JA, Safi K (2001) The impact of in situ Fe fertilisation on the microbial food web in the Southern Ocean. Deep-Sea Res Part II 48:2591-2613
Hasle GR (1969) An analysis of the phytoplankton of the Pacific Southern Ocean; abundance, composition and distribution during the Bratteg Exp. 1947-48. Hvalråd Skr 52:1-168
Heimdal BR (1997) Modern coccolithophorids. In: Tomas CR (ed) Identifying marine phytoplankton, Academic Press, San Diego, p 731-831
Hense I, Bathmann UV, Timmermann R (2000) Plankton dynamics in frontal systems of the Southern Ocean. J Mar Syst 27:235-252
Hutchins DA, Sedwick PN, DiTullio GR, Boyd PW, Quéguiner B, Griffiths FB, Crossley AC (2001) Control of phytoplankton growth by iron and silicic acid availability in the Subantarctic Southern Ocean: experimental results from the SAZ project. J Geophys Res 106:31559-31572
Kopczynska EE, Weber LH, El-Sayed SZ (1986) Phytoplankton species composition and abundance in the Indian sector of the Antarctic Ocean. Polar Biol 6:161-169
Kopczynska EE, Dehairs F, Elskens M, Wright S (2001) Phytoplankton and microzooplankton variability between the Subtropical and Polar Fronts south of Australia: thriving under regenerative and new production in late summer. J Geophys Res 106:31597-31610
Laubscher, RK, Perissinotto R, McQuaid CD (1993) Phytoplankton production and biomass at frontal zones in the Atlantic sector of the Southern Ocean. Polar Biol 13:471-481
Leblanc K, Quéguiner B, Fiala M, Blain S, Morvan J, Corvaisier R (2002) Particulate biogenic silica and carbon production rates and particulate matter distribution in the Indian sector of the Subantarctic Ocean. Deep-Sea Res Part II 49:3189-3206
Li WKW (1994) Primary production of prochlorophytes, cyanobacteria, and eukaryotic ultraphytoplankton: measurements from flow cytometric sorting. Limnol Oceanogr 39:169-175
Lochte K, Bjørnsen PK, Giesenhagen H, Weber A (1997) Bacterial standing stock and production and their relation to phytoplankton in the Southern Ocean. Deep-Sea Res Part II 44:321-340
McKenzie CH, Cox ER (1991) Spatial and seasonal changes in the species composition of armoured dinoflagellates in the Southwestern Atlantic Ocean. Polar Biol 11:139-144
Metzl N, Beauverger C, Brunet C, Goyet C, Poisson A (1991) Surface water carbon dioxide in the southwest Indian sector of the Southern Ocean: a highly variable CO2 source/sink region in summer. Mar Chem 34:85-95
Metzl N, Louanchi F, Poisson A (1998) Seasonal and interannual variations of the sea surface carbon dioxide in the subtropical Indian Ocean. Mar Chem 60:131-146
Metzl N, Tilbrook B, Poisson A (1999) The annual fCO2 cycle and the air-sea CO2 flux in the sub-Antarctic Ocean. Tellus 51B:849-861
Murphy LS, Haugen EM (1985) The distribution and abundance of phototrophic ultraplankton in the North Atlantic. Limnol Oceanogr 30:47-58
Nelson DM, Smith WO, Muench RD, Gordon LI, Sullivan CW, Husby DM (1989) Particulate matter and nutrient distributions in the ice-edge zone during late summer. Deep-Sea Res 36:191-209
Neveux J, Panouse M (1987) Spectrofluorometric determination of chlorophylls and pheophytins. Arch Hydrobiol 109:567-581
Nowlin WD Jr, Klinck JM (1986) The physics of the Antarctic Circumpolar Current. Rev Geophys 24:469-491
Paasche E (1973) Silicon and the ecology of marine plankton diatoms. I. Thalassiosira pseudonana (Cyclotella nana) grown in a chemostat with the silicate as limiting nutrient. Mar Biol 19:117-126
Pakhomov EA, Froneman PW (1999) The Prince Edward Islands pelagic ecosystem, south Indian Ocean: a review of achievements, 1976-1990. J Mar Syst 18:355-367
Pakhomov EA, McQuaid CD (1996) Distribution of surface zooplankton and seabirds across the Southern Ocean. Polar Biol 16:271-286
Park YH, Gamberoni L, Charriaud E (1991) Frontal structure and transport of the Antarctic Circumpolar Current in the South Indian sector, 40-80° E. Mar Chem 35:45-62
Park YH, Gamberoni L, Charriaud E (1993) Frontal structure, water masses and circulation in the Crozet Basin. J Geophys Res 98:12361-12385
Park YH, Pollard RT, Read JF, Leboucher V (2002) A quasi-synoptic view of the frontal circulation in the Crozet basin during the 'Antares-4' cruise. Deep-Sea Res Part II 49:1823-1842
Perissinotto R, Laubscher RK, McQuaid CD (1992) Marine productivity enhancement around Bouvet and the South Sandwich Islands (Southern Ocean). Mar Ecol Prog Ser 88:41-53
Perissinotto R, Lutjeharms JRE, Ballegooyen van RC (2000) Biological-physical interactions and pelagic productivity at the Prince Edward Islands, Southern Ocean. J Mar Syst 24:327-341
Piola AR, Figueroa HA, Bianchi AA (1987) Some aspects of the surface circulation south of 20° S revealed by First Global GARP Experiment drifters. J Geophys Res 92:5101-5114
Prieur L, Sournia A (1994) Processes and fluxes in the geostrophic Almeria-Oran front. J Mar Syst 5:187-203
Quéguiner B (2001) Biogenic silica production in the Australian sector of the Sub-Antarctic Zone of the Southern Ocean in late summer 1998. J Geophys Res 106:31627-31637
Ragueneau O, Tréguer P (1994) Determination of biogenic silica in coastal waters: applicability and limits of the alkaline digestion method. Mar Chem 45:43-51
Read JF, Lucas MI, Holley SE, Pollard RT (2000) Phytoplankton, nutrients and hydrography in the frontal zone between the Southwest Indian Subtropical gyre and the Southern Ocean. Deep-Sea Res Part I 47:2341-2368
Roberts PE (1980) Surface distribution of albacore tuna, Thunnus alalunga Bonaterre, in relation to the Subtropical Convergence Zone east of New Zealand. NZ J Mar Freshw Res 14:373-380
Sedwick PN, Ditullio GR, Hutchins DA, Boyd PW, Griffiths FB, Crossley AC, Trull TW, Quéguiner B (1999) Limitation of algal production by iron and silicic acid deficiency in the Australian Subantarctic region. Geophys Res Lett 26:2865-2868
Sedwick PN, Blain S, Quéguiner B, Griffiths FB, Fiala M, Bucciarelli E, Denis M (2002) Chemical limitation on phytoplankton growth in the Crozet Basin, Subantarctic Southern Ocean. Deep-Sea Res Part II 49:3327-3349
Smith WO Jr, Nelson DN (1990) Phytoplankton growth and new production in the Weddell Sea marginal ice zone in the austral spring and autumn. Limnol Oceanogr 35:809-821
Steyaert J (1973) Distribution of plankton diatoms along an African-Antarctic transect. Invest Pesq (Barc) 37:295-328
Sullivan CW, Arrigo KR, McClain CR, Comiso JC, Firestone J (1993) Distributions of phytoplankton blooms in the Southern Ocean. Science 262:1382-1387
Talbot V (1995) Activité protéolytique et dynamique bactérienne en Océan Austral. Thesis, Université Aix-Marseille II
Taylor FJR (1976) Dinoflagellates from the international Indian Ocean expedition. Bibl Bot 132:1-234
Tréguer P, Le Corre P (1975) Manuel d'analyses des sels nutritifs dans l'eau de mer. Utilisation de l'AutoAnalyzer II. Document Université de Bretagne Occidentale, Brest
Trousselier M, Courties C, Zettlemaier S (1995) Flow cytometric analysis of coastal lagoon bacterioplankton and picoplankton: fixation and storage effects. Estuar Coast Shelf Sci 40:621-623
Utermöhl H (1958) Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitt Int Ver Theor Angew Limnol 9:1-38
Van Ballegooyen RC, Grundlingh MI, Lutjeharms JRE (1994) Eddy fluxes of heat and salt from the southwest Indian Ocean into the southeast Atlantic Ocean: a case study. J Geophys Res 99:14053-14070
Veldhuis MJW, Kraay GW, Gieskes WWC (1993) Growth and fluorescence characteristics of ultraplankton on a north-south transect in the eastern North Atlantic. Deep-Sea Res Part II 40:609-626
Weeks SJ, Shillington FA (1996) Phytoplankton pigment distribution and frontal structure in the subtropical convergence region south of Africa. Deep-Sea Res Part I 43:739-768
